* Of course, it all begins with ARISTOTLE, who was quoted by Maltézos
* (1912). The oldest account of mirages seems to be Aristotle's brief
* mention in the "Meteorologica" (c. 340 or 350 BC) at 373 b in Book III
* (p.253 of the Loeb Library edition):
* "Distant and dense air does of course normally act as a mirror . . . ,
* which is why when there is an east wind promontories on the sea appear
* to be elevated above it and everything appears abnormally large;. . . "
* but unfortunately he then drags in the Moon illusion.
* So both MIRAGE and LOOMING were known to him.
* As Lee notes there, a similar (but much briefer) mention occurs in
* "Problems" XXVI. 53: "Why, when the east wind blows, do all the things
* seem larger?" Here are the Loeb Library editions:
* THEOPHRASTUS was Aristotle's successor; he's cited by A. von Humboldt.
* The fragment given in the footnote suggests he was familiar with
* superior mirages as well: "si mons versus aquilonem extenditur . . . ",
* though the translator obviously is not ("with what meaning I cannot
* see.")
* However, it is the inferior-mirage passage that Humboldt refers to:
* "If promontories seem to stand high out of the sea, or a single island
* looks like several . . . ."
* This is the Loeb Library edition; the "weather signs" section is
* apparently just tacked on, after "on odours". The subtitle is
* "with an English translation by Sir Arthur Hort, Bart., . . . ."
* AGATHARCHIDES (2nd Century BC) is known only from fragments of his
* historical work on the areas around the Arabian peninsula quoted or
* paraphrased by the later writers (Diodorus, Strabo, and Photius) who
* cite him as a source. The book cited here is an attempt to collect what
* remains of his work.
* Let's start with a mangled account of mirages in the desert. On p. 116
* (Book 5, Chapter 66 of Agatharchides) we have:
* "At the furthest reaches of Egypt and Trogodytice, . . . because of
* the extreme heat produced by the sun at noon people standing next to
* one another are unable to see each other because of the density of the
* air resulting from its condensation." [Evidently the original story was
* "people standing *near* each other" -- meaning, perhaps, "within hailing
* distance" as opposed to "far away". This is a correct observation of the
* shrinking of the apparent horizon by the inferior mirage, and the hiding
* of objects a few hundred meters away by the mirage. The distortion of the
* sense of the passage in re-copying is quite typical of what copy editors
* do today; it is particularly common in re-told accounts of mirages and
* other refraction phenomena by someone who has not personally seen them.]
* The next passage appears in both Photius and Diodorus, though in
* quite different forms. Here's Burstein's version of Photius; after
* commenting on the supposed lack of twilight at low latitudes: "Second,
* the sun appears to rise from the middle of the sea." [cf. Le Gentil's
* "whale" remark.] "Third, when it does rise, it is like a blazing coal,
* scattering great sparks, some into the disc of light and some beyond."
* [cf. the GF observers who speak of "flames" shooting out of the Sun.]
* "Fourth, people also say that the shape of the sun is not like a disc
* but most closely resembles a thick column which appears fatter at the
* end as if it had a head." [Ch. 107, p. 171] Here Burstein cites Salt,
* (1814) p. 93, for a similar description (q.v., below).
* DIODORUS SICULUS has the next earliest (c. 30 BC) known description of
* mirages. Oldfather's translation makes good sense, but he seems not to
* have appreciated the significance of this passage:
* "And both in this land and in Libya which lies beyond the Syrtis there
* takes place a marvellous thing. For at certain times, and especially when
* there is no wind, shapes are seen gathering in the sky which assume the
* forms of animals of every kind; and some of these remain fixed, but
* others begin to move, sometimes retreating before a man and at other times
* pursuing him, and in every case, since they are of monstrous size, they
* strike such as have never experienced them with wondrous dismay and
* terror. . . . although the natives, who have often met with such things,
* pay no attention to the phenomenon."
* "As for the movements which these shapes make in both directions, these
* . . . indicate no volition on their part, since it is impossible that
* voluntary flight or pursuit should reside in a soulless thing. And yet
* the living creatures are, unknown to themselves, responsible for this
* movement through the air; for, if they advance, they push by their violent
* motion the air which lies beneath them, and this is the reason why the
* image which has formed retreats before them and gives the impression of
* fleeing; whereas if the living creatures withdraw, they follow in the
* opposite direction, the cause having been reversed . . . . Consequently it
* has the appearance of pursuing men who withdraw before it, for the image
* is drawn to the empty space and rushes forward in a mass under the
* influence of the backward motion of the living creature. . . ."
* (from Book III.50 and .51)
* The need for calm air is repeated three times.
* QUINTUS CURTIUS RUFUS (History of Alexander, Book VII; c. 40 A.D.)
* The reference here is Curt. 7.5.4:
* "Then too a mist [caligo], aroused by the excessive warmth of the ground,
* obscures the light, and the aspect of the plain is not unlike that of a
* vast and deep sea."
* Many thanks to Prof. J.C.Yardley of the University of Ottawa for finding
* this passage!
* PLINY in the Loeb Library edition
* This passage from the "Natural History" is obviously not what Kircher
* had in mind: (from Book II, section LVIII)
* "In the third consulship of Marius the inhabitants of Ameria and Tuder
* saw the spectacle of heavenly armies advancing from the East and the West
* to meet in battle, those from the West being routed." (Vol. I, p. 285)
* William Whiston's translation of FLAVIUS JOSEPHUS (c. 78 A.D.)
* This translation has been widely reprinted, up to the present day.
* It is also available on the Perseus website at http://www.perseus.tufts.edu
* and at http://www.coel.wheaton.edu.
* The passage suggestive of a mirage is in Book VI, Chapter V, section 3
* of the "Wars of the Jews" (near paragraph 289). He enumerates several
* omens around the time of the feast of unleavened bread, almost a week
* before Passover:
* "Besides these, a few days after that feast, on the one-and-twentieth
* day of the month Artemisius, [Jyar,] a certain prodigious and incredible
* phenomenon appeared; I suppose the account of it would seem to be a fable,
* were it not related by those that saw it, and were not the events that
* followed it of so considerable a nature as to deserve such signals; for,
* before sun-setting, chariots and troops of soldiers in their armour were
* seen running about among the clouds, and surrounding of cities."
* This does indeed sound much like a superior mirage or Fata Morgana.
* Cf. l'Astronomie 7, 392-393 (1888).
* Very EARLY MIRAGE descriptions (1558) by Antonius de Ferrariis (1444-1517)
* or Antonio de Ferarri, also known as Antonio Galateo, Galateus Antonus, etc.
* after his place of birth (Galatone).
* Supposedly written in 1507-1509, but only published in 1558.
* Japygia is the old name; it became Apulia, and then Puglia.
* This passage is translated from the recent (2005) Latin/Italian version
* "La Iapygia" edited by Domenico Defilippis (Mario Congedo, Galatina):
* [18 10] (pp. 92/93): "In these swamps [near Nardò, on the Gulf of
* Taranto], as also in the fields of Manduria and Baleso and Copertino,
* certain apparitions are seen, which are called Mutationes or Mutata .
* The common people tell tales of I don't know what, vampires or witches or,
* as they say in Naples, janare [fairies], or as the Greeks say, nereids.
* It's amazing: this nonsense takes possession of the whole region and
* misleads the poor people. With no reliable authority, no reason, no
* demonstration, everyone believes in things they have not seen and are
* not true. And we oppose the testimony of the most ignorant people; we
* believe they are childish fantasies and old wives' tales, giving more
* trust to the ear than the eye. No one is an eye-witness, all accept
* what they have heard from others." (He then goes off to condemn popular
* beliefs in magic potions that can turn women into various animal forms
* at night; vampires; and other superstitions.) Then: "But let us return
* to those apparitions."
* [18 18] (pp. 96/97) "And sometimes you will see cities and castles and
* towers, and sheep and different colored cattle and images or specters of
* other things, where there is no city, no sheep, not even a thorn bush.
* I myself have sometimes had the pleasure of seeing these plays, this
* lusus naturae .
* "They do not last long, but change as the vapors in which they appear,
* from one place to another, from one form to another, whence perhaps they
* are called Mutata , or because the sky is changed from sunny to rain
* by these apparitions.
* "This happens in the morning, with calm air, beginning with a light
* breath of air (customarily) from the south. For as the strong south
* wind ceases, so at first it is gentlest and, as it is warm, it raises
* tenuous mists, which reflect images of cities, flocks, and other things
* like a mirror.
* "And like the vapors, those images are moved, as things are seen
* moving in mirrors that are moved and shaken. And because the things
* directly face the vapors, they are seen directly, just like a shadow
* which falls opposite a luminous body; those that are oblique and turned
* produce images, which we also see turned, as also in water we see the
* tops of mountains and roofs at the bottom. For when some things are
* closer to the surface of the water, such as a foundation, to our vision
* they would appear far off; the images of rooftops, which are farther
* from the water, come nearer to us, and therefore are seen below.
* "And so we find that in a closed building, with a little light coming
* through the slits, everything is seen reversed, such as the head of a man
* downward, feet above. For the lines of shadows do not proceed directly,
* but are transposed and intersect in the middle. This same thing happens
* in a concave mirror, so that the upper part of the mirror reflects the
* lower part of the thing seen, and the lower the upper.
* "These apparitions that I have mentioned often deceive the gaze of
* travelers, who, when they suppose they are near a city, are very far away.
* And there have been seen in this region images in the air of men riding
* horses and marching on foot. And so writers have recorded that armed
* troops arrayed for battle have been seen in the sky, and these (as I
* think) images were of those far away from that place in which the images
* were seen, and could not be seen [directly].
* "And thus we don't see a coin in the bottom of a vessel, but if the
* same vessel is filled with water, we see not the coin, but its image at
* the surface of the water, which is touching the air. For the surface
* of the water is analogous to the surface of a mirror, but whether these
* images may belong to the mirror, or the outer surface of the air, is
* another question." And he cites Aristotle. [18 24] (pp. 98/99)
* "And as these figures are of mists, they give likenesses of ships
* and sails, where there is no fleet. These apparitions deceive not only
* the inexperienced. It is not long since the whole coast, from Hydrunto
* [Otranto] to Monte Gargano, at one and the same hour before sunrise,
* saw a fleet sailing from the east. It was thought to have been that
* of the Turks, and before that specter or delusion was revealed by
* the lightening dawn, various letters were composed here and there and
* messengers were sent concerning the approach of this imposing fleet."
* [NOTE: a Turkish fleet had just sacked Otranto in 1480, a few years
* before this was written; he assisted in its liberation.] He continues:
* "Perhaps in this way or another of which we shall speak, as I believe,
* someone (I don't know who) from Lilibeo [Marsala] saw a fleet leaving
* the port of Carthage."
* The 1558 edition was recently republished by Forni.
* Thomas Facellus (Tommaso Fazello) briefly mentions mirages
* Cited by Minasi; and, following him, P&E (p.170). They give the citation
* as Dec. 1, lib. II, cap. 1.
* The title page is imaged at
* http://edit16.iccu.sbn.it/scripts/iccu_ext.dll?fn=60&i=18660#1
* The passage appears on p. 42 of the edition at the HathiTrust website:
* http://babel.hathitrust.org/cgi/pt?id=ucm.5325123864;view=1up;seq=64
* "Sed & alia in hoc freto res mira frequenter apparet. Nam mitigato
* turbine, quietoq; aere, circa diei exortum illucescente aurora, variæ
* animantium, hominumq; formæ in aere crebrò cernuntur. Quarum aliæ
* penitus immotæ sunt, pleræq; vel in aere discurtunt,vel inter se
* dimicant, quousq; Sole incalescente, è conspectu eripiantur:Harum
* Polycletus lib. de Reb.sicul.& Aristoteles lib.de mirab.aud. memi-
* nerunt, quarum etiam haec à Philosophis redditur ratio : quod cùm in
* ijs regionibus,eo præsertim tempore,quo haec cernuntur,ventos, aut
* omnino non spirare,aut exiles admodum,& aerem quietum esse constet,
* in ipso aere denso atq; obtuso diuersæ animantium effigiantur species,
* quibus formam aer, quem tenues & leues quandoq; mouent auræ, variam
* præbet (quemadmodum æstate in nubibus fieri videmus) qua tandem sol
* incalescens in ventos resoluit."
* (Panormi = Palermo)
* MARC'ANTONIO POLITI -- the first to use the term "Fata Morgana"
* Briefly quoted by Costanzo (1903), p. 106.
* ATHANASIUS KIRCHER (1646)
* This is the work cited by Castberg. The discussion of mirages and other
* meteorological phenomena is in Liber decimus, Pars secunda, pp. 800-804.
* "Liber decimus. Magia Lucis & Vmbrae . . . Pars Secunda. Magia
* Parastatica, siue de repræsentationibus rerum prodigiosis; per Lucem &
* Vmbram . . . Caput 1 De Repræsentationibus aeris: mentions "in libris
* Machabeorum" (p. 800)
* "Parastatis I Naturae, siue de Morgana Rheginorum in Freto Mamertino,
* siue Siculo" -- here, on p. 801, we have "Vocant autem Rhegini hoc
* spectaculum Morganam," followed by Ignatio Angelucci's letter to Leone
* Sanzio, describing a Fata Morgana display on Aug. 15, 1643. [Angelucci's
* letter is also quoted by Capozzo (1840).] Note that Angelucci says he
* saw his F.M. "La mattina dell' Assontione della Beatissima Vergine,"
* and does not give a calendar date. This led to some confusion later.
* [His letter is "Di Reggio", dated the 22. of August.]
* p.802 mentions "Scipio Mazzellus, Regni Neapolitani; fol. 117".
* p. 803: "Refert Pomponius Mela, in Mauritania retro Atlantem regiones
* esse, in quibus circa meridiem inter montes varia spectra comparere
* soleant, quae gestus hominu' in omnibus æmulentur: videas ibi choreas,
* audias tubarum, tympanorumque strepitus. Refert quoque Plinius, intra
* Imaum in Scythia regionem esse, in qua quot-annis in vasta planitie
* appareant varia spectacula rerum sub figura hominum animaliumque, &
* instar exercitus; quibus viatores non rarò in auia, & deuia
* præcipitia ac denique in manifestam perniciem deducantur. Ad
* flumen Oby refert Haithon Armenus regionem esse, ad quam nullus adhuc
* penetrauerit, ob formidabilium, spectrorum, quae ex illa fluminis parte
* comparent, multitudinem."
* The reference to Pomponius Mela seems to be nonsense; there is nothing
* like this in his book. I have not found the Pliny passage, either.
* (For more evidence of Kircher's unreliability, see Lohne's 1959 paper
* on Harriot.)
* NOTE: a revised edition of this was printed in Amsterdam in 1671.
* Due to the removal of some material, Angelucci's letter appears in
* it on pp. 704-705 rather than p. 801. Many later commentators have
* referred to that edition instead of the original; see the entries for
* Giardina (1758), Minasi (1773), Boccara (1902), etc.
* Placido Reina quotes Politi, Facellus, etc.
* The Fata Morgana begins on p. 64, and "similar things" on p. 65.
* Politi is cited on pp. 65 and 67. See Costanzo's (1903) discussion
* at his p. 107; esp. the footnotes there.
* Available at Google Books.
* EDME MARIOTTE's short monograph on the optical level and its use
* Mainly of historical interest; first, because of Forel's use of his
* technique for the easy measurement of absolute altitudes; and second,
* for his discussion of temporal VARIATIONS in TERRESTRIAL REFRACTION.
* That discussion is mainly on pp.19-20; but it arises from the calculations
* on p. 18, where the diameter of the Earth is taken to be 40 million feet.
* His concern there is that the height of a distant object on the tangent
* plane at the observer is above the observer's height. But, he says,
* "Il est encore necessaire de sçavoir que dans les grandes distances
* un mesme objet paroist de differentes hauteurs par les refractions,&
* change presq'uà toutes les heures du jour,c'est à dire que s'il est le
* matin au lever du Soleil en une mesme ligne droite avec un objet prochain,
* il paroistra plus bas une heure aprés le Soleil levé, & encore plus bas
* quand l'air sera plus échauffé,& plus les matinées seront fraisches &
* l'air serain, plus les objets éloignez paroistront élevez, & quelques
* fois les objets qui sont à une distance d'environ 500 pas paroistront
* s'élever, & en mesme tems ceux qui sont beaucoup éloignez s'abaisser,
* principalement lors que le Soleil luit, comme on a reconnu par plusieurs
* observations faites en divers lieux & diverses saisons,mesme à l'égard
* des objets moins élevez que observateur,ou d'égale hauteur ; & on a
* remarqué quelquefois, qu'un objet qui avoir paru à midy plus bas que
* le plan de niveau, paroissoit le lendemain matin plus de 20 pieds plus
* haut que ce plan, en une distance d'environ 2 lieuës, d'où il s'ensuit
* que le plus seur moien pour bien niveller de grandes distances, est
* de le faire à plusieurs fois: . . . " whereupon he gives an example,
* referring to Figs. 12 and 13 at the end of the volume. This discussion
* of refraction continues on to p. 22.
* He mentions refraction again on p. 27 and p. 31, where he remarks that
* the refractions are "irregular" when the Sun shines; on the next page,
* he says that reliable measurements can be made when the sky is covered
* with clouds. So, although he give no systematic measurements, it's clear
* from the numerous examples that he was familiar with the variations and
* regularities in terrestrial refraction.
* A good PDF of this work is available at
*
* https://gallica.bnf.fr/ark:/12148/bpt6k6514207h?rk=21459;2
*
* which scrupulously puts "[sic]" after Mariotte's odd title spelling.
* However, BNF's OCR frequently renders the long-s as "f".
* HEVELIUS (1674)
*
* "Under the Sun, towards the Horizon, there hung a somewhat dilute small
* Cloud, beneath which there appear'd a Mock-Sun, of the same bigness (to
* sense) with the true Sun, and under the same Vertical, of a somewhat red
* colour. Soon after, the true Sun more and more descending to the Horizon,
* towards the said Cloud (as may be seen Fig. 4) the spurious Sun beneath it
* grew clearer and clearer, so as that the reddish colour in that apparent
* Solar disk vanish'd, and put on the genuine Solar light, and that the more,
* the less the genuine disk of the Sun was distant from the false Sun: Till
* at length the upper true Sun passed into the lower counterfeit one, and so
* remained alone; as appears Fig. 5.
*
* "Which Appearance being unusual, and having never been seen by me, I took
* the freedom of imparting it unto you, especially since here the Mock-Sun
* was not found at the side of the true Sun, as 'tis wont to be in all
* Parhelia's seen by me, but perpendicularly under it; not to mention the
* Colour, so different from that which is usual in Mock-Suns; nor the great
* length of the Tayl, cast up by the genuine Sun, and of a far more vivid and
* splendid light, than Parhelia's use to exhibit. Upon this appearance there
* soon follow'd here an exceedingly intense and bitter Frost, whereby the
* whole Sinus Puzensis was frozen up from this Town of Dantzick, as far as
* Hela in the Baltick Sea, which lasted unto the 25th of March; and the Bay
* was frozen so hard, that with great safety people run out into it with Sleds
* and Horses, for several of our Miles. Whether the recited Phaenomenon have
* had any influence for this extream Cold, I know not, but leave it for
* Astrologers to examine. Whether the like Appearance have ever been
* observ'd in England, I should be glad to be informed of."
* Translation of Pierre Perrault's "De l'origine des fontaines" (1674)
* and so filed here instead of at 1967. Orig. pub. by Pierre le Petit,
* Paris (1674).
* "Moreover the astronomers are certain that humid vapors either of the
* Sea, or of the Earth, cause much refraction, and cause many things to be
* seen otherwise than they really are: as when the Sun or the Moon
* sometimes appear to be oval, when they rise or set; . . . ." He then
* mentions their appearance "on the horizon before they have risen up to
* it," and offers the coin in a basin filled with water as an illustrative
* demonstration. In section (111): "I have made another more elaborate
* experiment, which shows that the vapors of the earth, according to their
* arrangement, can make distant objects appear now higher now lower, as if
* these objects were really raised or lowered. . . . I took as an object a
* pavilion about thirty-two feet in height half a league away, which I
* observed with a spyglass attached to and rendered motionless on a window
* sill in a large wall; and having aimed it at the top of this pavilion,
* which was on the thread of my spyglass, and level with it; I found that
* from two o'clock in the afternoon, when I began my observation, until
* night, the top of this roof had seemed to rise by eight feet, so that
* more than half this roof was above the thread of my spyglass." [He goes
* on to relate several days' observations, during which the building rose
* and fell by more than its full height.] "I have repeated the same
* experiment at another time when there was a great drought, which had
* lasted more than six weeks without respite, and I have always seen the
* same thing . . . the rising of my object happened regularly from noon to
* evening, and the lowering from morning to noon. . . ." (pp. 58-60)
* The translator suggests (p.182) that "this may be the earliest study"
* of such DIURNAL VARIATIONS in atmospheric refraction. N.B.: "half a
* league" is about 2 km; the building was about 10 m high; so the variations
* cover a range of about 1/200 radian or some 16' of arc.
* Note that the book is dedicated to Christiaan Huygens, who picked up
* the refraction variations in his "Traité de la Lumière" (1690).
* Jean Picard's inferior mirage seen at Tycho's old observatory
* "Je mets à part les changemens qui arrivent à cause des Réfractions,
* & je diray seulement une chose que nous remarquasimes en faisant
* les Observations que nous venons de rapporter. Il y a proche de
* Copenhague une Isle appellée Amac, dont le terrain qui est assez bas
* nous estoit caché par la rondeur de la mer, en sorte néanmoins que nous
* y découvrions les sommets de quelque arbres. Or venant à pointer le
* quart de cercle vers l'endroit où ces arbres me paroissoient tranchez,
* j'estois asseûré que mon Rayon visuel recontroit l'extrémité visible
* de la surface de la mer, & néanmoins on auroit dit que ces arbres
* estoient dans le Ciel, & que la mer estoit terminée bien au dec,à de
* l'endroit où nous sçavions qu'il falloit pointer. La raison de cette
* apparence, est que la mer estoit fort unie, faisoit à nostre égard si
* exactement l'effet du miroir, que nous la confondions avec le Ciel."
* (Probably this is the island of Amager, where Copenhagen's airport is
* today -- about 30 km south of Hven.)
* This memoir contains much else of interest: an eyewitness account of
* Tycho's original records, and his celestial globe: "nonobstant toutes
* les fortunes qu'il a couruës, ayant esté premiérment transporté de
* Dannemarck en Boheme, puis en Silesie, & enfin rapporté in Dannemarck,
* il est en dans son entier comme s'il venoit d'estre fait : son diametre
* est précisément de quatre pieds, sept pouces & une ligne, mesure de
* Paris." (p. 4)
* Picard also enjoyed the collaboration of Erasmus Bartholin, who
* accompanied him to Uraniburg, as well as "un jeune Danois nommé
* Olaüs Romer, que M. Bartholin m'avoit fait connoitre, & qui estant
* ensuite venu en France avec moy, fut de l'Académie des Sciences, où
* il a donné plusieurs marques de son rare génie & se son esprit." (p.5)
* He found Tycho's observatory completely destroyed, and the remains
* scattered. Placing his instruments on the surviving foundations of
* Tycho's observatory, he determined its location: the ground was about
* 27 toises [52.6 m] above the sea (p. 7); a latitude of 55° 54' 15''
* (p. 25); and a longitude 42m 10s or 10° 32' 30'' E of Paris. (p.28)
* His stay in November 1671 was so difficult that "enfin le travail des
* veilles durant un froid auquel je n'estois pas accoustumé, & l'air de
* la Mer Baltique me causerent une langueur qui renoit un peu de scorbut,
* & qui me fit à la fin résoudre à quitter cette solitude, pour me
* retirer dans un lieu de secours avant que les glaces me fermassent
* le passage." (p.12) (He notes on the next page that scurvy was common
* "aux personnes sedentaires".) But he sent Romer back in the spring,
* to finish the observations.
* Then, on p. 18, we find he has noticed (but not understood) the
* effects of annual aberration, "que j'observe depuis dix ans." Not bad!
* Thanks to Sharron Huling for providing a photocopy!
*
* Earliest mention seems to be in JOHN WINTHROP's Journal
* In the entries for 1648, we find on p. 346:
* ``There appeared over the harbor at New Haven, in the evening, the
* form of the keel of a ship with three masts, to which were suddenly
* added all the tackling and sails, and presently after, upon the top of
* the poop, a man standing with one hand akimbo under his left side, and
* in his right hand a sword stretched out toward the sea. Then from the
* side of the ship which was toward the town arose a great smoke, which
* covered all the ship, and in that smoke she vanished away; but some saw
* her keel sink into the water. This was seen by many, men and women, and
* it continued about a quarter of an hour.''
* [cf. the FOG FILE for the "smoke".]
* A footnote says: "The spectral ship of New Haven, the tradition of
* which was taken up and characteristically developed by Cotton Mather, is
* one of the most weird of New England legends, and has become familiar to
* the later generations."
* Leonard Bacon's account, largely taken from Winthrop's
* Here, after describing the loss of the ship sent out in January, 1646,
* he says: ``Two years and five months from the sailing of that ship, in
* an afternoon in June, after a thunder storm, not far from sunset, there
* appeared over the harbor of New Haven, the form of the keel of a ship
* with three masts, to which were suddenly added all the tackling and
* sails; and presently after, upon the highest point of the deck, a man
* standing with one hand leaning against his left side, and in his right
* hand a sword pointing towards the sea. The phenomenon continued about a
* quarter of an hour, and was seen by a crowd of wondering witnesses, --
* till at last, from the farther side of the ship, there arose a great
* smoke, which covered all the ship; and in that smoke she vanished
* away.''
* A footnote calls it an "atmospheric phenomenon"; mirages were well known
* by 1839, when this was published.
* COTTON MATHER's belated third-hand account
* This quotes a secondary source -- a letter from James Pierpont, who
* was pastor of the First Congregational Church of New Haven from 1685 to
* 1714, and therefore could not himself have been a witness. His
* second-hand account, reported to Mather in a letter, has the year of the
* original sailing wrong; and the details are by now vastly exaggerated by
* the fading memories of the (unnamed) witnesses:
* "In Compliance with your Desires, I now give you the Relation of
* that Apparition of a Ship in the Air , which I have received from the
* most Credible, Judicious and Curious Surviving Observers of it.
* "In the Year 1647, besides much other Lading, a far more Rich
* Treasure of Passengers, (Five or Six of which were Persons of chief Note
* and Worth in New-Haven ) put themselves on Board a New Ship , built at
* Rhode-Island , of about 150 Tuns; but so walty, that the Master,
* (Lamberton ) often said she would prove their Grave. In the Month of
* January , cutting their way thro' much Ice, . . . they set Sail. Mr.
* Davenport in Prayer with an observable Emphasis used these Words,
* Lord, if it be thy pleasure to bury these our Friends in the bottom
* of the Sea, they are thine; save them! The Spring following no
* Tidings of these Friends arrived with the Ships from England:
* New-Haven's Heart began to fail her: This put the Godly People on
* much Prayer , both Publick and Private, That the Lord would (if it was
* his Pleasure) let them hear what he had done with their dear Friends,
* and prepare them with a suitable Submission to his Holy Will. In
* June next ensuing, a great Thunder-storm arose out of the
* North-West : after which, (the Hemisphere being serene) about an Hour
* before Sunset a SHIP of like dimensions with the aforesaid, with her
* Canvas and Colours abroad (tho' the Wind Northernly) appeared in the Air
* coming up from our Harbour's Mouth, which lyes Southward from the Town,
* seemingly with her Sails filled under a fresh Gale, holding her Course
* North, and continuing under Observation, Sailing against the Wind for
* the space of half an Hour. Many were drawn to behold this great Work
* of God; yea, the very Children cry'd out, There's a Brave Ship! At
* length, crouding up as far as there is usually Water sufficient for
* such a Vessel, and so near some of the Spectators, as that they imagined
* a Man might hurl a Stone on Board her, her Maintop seem'd to be blown
* off, but left hanging in the Shrouds; then her Missen-top ; then all
* her Masting seemed blown away by the Board: Quickly after the Hull
* brought unto a Careen , she overset, and so vanished into a smoaky
* Cloud, which in some time dissipated, leaving, as everywhere else, a
* clear Air."
* To which, Mather adds: "Reader, There being yet living so many
* Credible Gentlemen, that were Eye-Witnesses of this Wonderful thing, I
* venture to Publish it for a thing as undoubted , as 'tis wonderful ."
* (Mather's book originally appeared in 1702.)
* Mather's account enshrined by the poet Longfellow
* (Thanks to Penny Porter for pointing this out!)
* A brief modern mention by Isabel MacBeath Calder
* On pp. 160-161 there is a description of "the attempt to build
* transatlantic vessels on Long Island Sound." The launch of the first
* ship, ``ill built and very `walt-sided,' '' in January, 1646, is
* described. On p. 161: ``After the lapse of many months a mirage of
* the ship was said to have appeared over the harbor at New Haven, but the
* vessel itself neither reached its destination nor returned to its port
* of departure.''
* Numerous citations are offered: New Haven Colonial Records,
* 1638-1649 , pp. 147, 283, 329-333, and ``Roxbury Land and Church
* Records,'' Record Commissioners of the City of Boston, Sixth Report ,
* p. 190 are not available to me; the others are cited here.
* (see also "Crocker Land" and "W.H.Lehn" files)
*
* ORIGIN of the word "MIRAGE":
*
* The 1687 French dictionary that defines "La terre se mire":
* "Cela se dit lors que les vapeurs font paroître les terres comme si
* elles étoient élevées sur de basses nuées." (p. 352)
* by Nicolas Desroches
* At
* https://www.livres-anciens-et-modernes.fr/accueil/300-nicolas-desroches-dictionnaire-des-termes-propres-de-marine-1687.html
* we read that "Nicolas Desroches fut lieutenant de vaisseau en 1671 et
* capitaine en 1693."
* Thanks to Eric Frappa for finding this reference!
* available at Google Books;
* https://books.google.fr/books?id=HcoeqZRLeKsC&printsec=frontcover&hl=fr#v=onepage&q&f=false
*
* ORIGIN of the word "MIRAGE":
* The old French/Dutch dictionary by Nicolas Aubin
* Defines "La terre se mire" on p. 565. The wording given there is almost
* identical to that used by Le Gentil (1789), who says he got it from the
* 1736 edition; there was also a 1742 (3rd) edition. The first edition was
* this one, in 1702. Its definition seems taken from the 1687 dictionary by
* Desroches, with minor changes.
* Thanks to Eric Frappa for finding this reference!
* available at Google Books
* Modern comments on the origin of "mirage"
* Jacques Gronier, Attaché to the French Consulate at Malta, responds to
* Richard Beck's article (16 March), supplying good English translations:
* "In the report of Monge, entitled `On the optical phenomenon known
* under the name of mirage', and published in the Reports of the
* Institute of Cairo, one reads textually the following: 'It [the
* phenomenon] is well known to sailors, who frequently observe it at sea
* and who have given it the name of mirage. In truth, the cause which
* produces the mirage at sea may well be different from that which produces
* it on land; but the effect being absolutely the same in the two cases,
* I did not believe it necessary to employ a new word.'
* "It is plainly apparent from this that the term had not been
* invented by Monge and that it was in previous use. Some years later,
* the physicist Biot, also a member of the Academy of Sciences, gave the
* theory of the phenomenon. His report, read on 8 August, 1808, began thus:
* "'Physicists and astronomers have for a long time observed that
* objects which are seen very near to the horizon sometimes transmit to
* the observer two images, one upright, the other inverted. No one is
* better placed than sailors to observe this phenomenon and it is well
* known to them: they designate it by a very expressive name in calling
* it the mirage, because indeed it then seems that objects are reflected
* as in a mirror.
* 'In the volume of the History of the Royal Academy of Sciences, for the
* year 1753, printed in 1757, one finds on page 253, in the account made to
* the Academy by M. de Chabert, Lieutenant-Commander, of the voyage which he
* made by order of the King, in 1750 and 1751, to rectify the maps of Acadia
* and of Newfoundland, the following paragraph:
* 'While M. de Chabert was occupied in drawing up the plans of which we
* spoke above, he was often stopped by a singular phenomenon, that is called
* a mirage: it is an apparent change in the aspect of the shores a little
* way away, which the inhabitants attribute to the reflection of the sky
* which, mirrored in the water, makes the shore appear lifted in the air
* and which M. de Chabert believes, with great probability, is caused by
* the irregularities of refraction often undergone by terrestrial objects.'
* "These extracts open the way to new researches. In effect,
* this phenomenon of refraction, although it has often given place to
* interpretations scientifically incorrect, seems to have been observed,
* from very distant times, by the navigators who have certainly not omitted
* to report it.
* "It is probable that in the archives of the Musee de la Marine in
* Paris and, in particular, in the old 'log books' which are preserved
* there, the oldest references to the word mirage may be discovered."
* MIRAGE OBSERVATIONS
*
* EARLIEST LOOMING? (Maraldi, cited by de Chabert, 1755); and indirectly
* referred to by Biot (1805).
* Giacomo Filippo Maraldi -- by now, Jacques Philippe Maraldi -- was
* the nephew of Giovanni Domenico (or Jean Dominique) Cassini.
* This is indeed mostly about determining the coordinates of several
* places on and near Corsica; but our interest is in the introductory
* remarks:
* "On voit des Côtes de Genes & de Provence les Montagnes de l’Isle de
* Corse, qui paroissent quelquefois élevées au-dessus de l'horison
* sensible , comme si elles sortoient de l’eau , & qui disparoissent
* en d'autre temps par un Ciel également pur & serein , comme si elles
* s’étoient plongées dans la Mer.
* "Il y a des saisons plus propres pour découvrir cette Isle des
* côtes de Genes, qui sont le Printemps & l’Automne. On la voit aussi
* quelquefois l‘Hiver; & les heures du jour qu’elle paroît , sont le
* matin au lever du Soleil , & un peu avant , ou bien le soir , un peu après
* son coucher. On la voit aussi quelquefois dans le même jour le matin &
* le soir , & elle se perd entierement de vûe le reste de la journée.
* "Toutes ces apparences se font sur les Côtes de Genes, par rapport
* à un Observateur qui esi toujours dans la même situation & à la même
* hauteur sur la surface de la Mer.
* "On pourroit attribuer cette diverfité d’apparence à la variation
* qui arrive à la hauteur des eaux de la Mer , qui sont entre Genes &
* la Corse; car quoique , suivant l’opinion commune des Philofophes , la
* surface de la Mer soit sphérique, il faut avouer que cette figure est
* sujette à des variations qui lui arrivent par des causes extérieures ,
* dont les principales font les courants, aussi-bien que le flux &
* le reflux, & qui font varier confiderablement la hauteur de l’eau
* dans le même lieu.
* "Suivant cette idée, on pourroit dire que l’Isle se découvre
* lorsque la mer est basse : au contraire la Corse se doit perdre de vûe
* du même lieu , lorsque la Mer s’éleve & se place entre deux.
* "Mais cette explication n’est pas la plus naturelle , & il est
* plus vrai-semblable d‘attribuer ces apparences aux réfractions ,
* & de supposer que les rayons visuels qui viennent de cette Isle à
* l‘Observateur qui est sur les Côtes opposées, se rompent diversement
* dans les vapeurs qui sont entre deux; ainsi, lorsque les vapeurs sont
* plus denses ou en plus grande quantité, les réfractions des rayons
* sont plus grandes, & font paroître l'Isle au-dessus de la Mer, &
* lorsque les vapeurs sont moins denses , ou qu’il y en a une moindre
* quantité répandue dans l’air , les réfractions des rayons étant
* plus petites , l’Isle reste cachée par la Mer.
* "Cette explication paroît d’autant plus vrai-femblable , qu’elle
* est également propre à rendre raison des apparences semblables qui
* arrivent au milieu des Terres ; car on a remarqué depuis longtemps à
* l’Observatoire, des maisons éloignées de fept ou huit lieues ves [sic]
* le Nord , qui étant cachées pendant le jour par d’autres maisons qui
* sont plus proches, & placées seulement à une demi-lieue de distance,
* paroissent souvent le matin au lever du Soleil, élevées au-dessus de
* celles qui sont proches. Ces maisons éloignées s’abaissent ensuite
* peu à peu , jusqu'à ce qu’elles se cachent entierement pendant le
* jour par les Maisons qui sont proches. Cette apparence est donc une
* preuve évidente , que les rayons se courbent dans l’air différemment ,
* suivant les différentes densités de l’air, ou suivant la différente
* quantité de vapeurs par où ces rayons passent. Cela prouve aussi que
* le matin les vapeurs sont plus denses , ou bien qu’il y en a dans
* l’air une plus grande quantité que le reste du jour. L’apparence
* que fait la Corse , vûe de Genes , étant semblable à celle que nous
* venons de rapporter , on en peut rendre raison de la même maniere.
* "M. le Marquis Saluago a observé très souvent ces apparences que
* fait l’Isle de Corse , d’une Maison qu’il a proche de Genes vers
* le Nord . . . ." -- and here he takes up the details of the surveying,
* remarking that the height of that observatory was 50 toises (about
* 97 meters) above sea level.
* On p. 351, he says that this height, together with the size of the
* Earth's radius determined by the Academy, predicts a geometrical dip
* of the horizon of 18 minutes; but the observed dip is only 16' 0" to
* 17' 30", which is smaller. This difference should be attributed to the
* refraction of the rays between the horizon and the quadrant.
* The first paragraph describes an appearance corresponding to inferior
* mirages. Subsequent descriptions of variations in terrestrial refraction
* correspond to looming and sinking; and the diurnal variations are a more
* detailed description of those reported in Perrault's "De l'origine des
* fontaines" (1674).
* The best visibility of the distant mountains (over 260 km from Genoa)
* just before sunrise and just after sunset is due to the illumination
* of the intervening lower atmosphere by the Sun, when it is above the
* observer's horizon. When the Sun is just below the horizon, the distant
* peaks are silhouetted against the brightly illuminated upper troposphere.
* The apparent motion of distant houses relative to nearer ones that are
* visible at daybreak and sink out of sight in the middle of the day, is
* direct observation of changes in the apparent curvature of the Earth's
* surface, due to changes in lapse rate in the boundary layer.
* In short, lots of good observations of DIURNAL VARIATIONS in refraction
* that are understandable today, but were remarkably mysterious four
* centuries ago.
* Cited by de Chabert (1753), and mentioned by Le Gentil (1789).
* [cf. Perrault (1674); Delambre (1814); Williams, Mudge, and Dalby (1795);
* Atkinson (1826); etc.]
* Dated 28. Mars, 1722.
* Available at BHL., and at Gallica:
*
* https://gallica.bnf.fr/ark:/12148/bpt6k3524k/f1.item
*
* EARLIEST LOOMING? (THOMAS SHAW, D.D.; cited by T.Jefferson, 1787)
* On the title page, Shaw is merely "Fellow of Queen's-College in
* Oxford, and F.R.S."; but on the title page of the 1746 Supplement
* (bound together with the original in the copy I managed to borrow), he
* is also "Principal of St. Edmund Hall, and Regius Professor of Greek,
* in the University of OXFORD."
* In Chap. III, p. 358, "Physical Observations &c. or an Essay towards
* the Natural History of Syria, Phœnice, and the Holy Land," we find
* the passage cited by Jefferson:
* "We are likewise to observe further with Regard to these strong
* Easterly Winds, that Vessels or any Objects which are seen, at a
* Distance, appear to be vastly magnified, or loom , according to the
* Mariners expression." [N.B.: p. 362 -- not 302!]
* But more surprising is the passage in Chap. IV, "Physical Observations
* &c. or an Essay towards the Natural History of Arabia Petræa" (p.377):
* "Where any Part of these Deserts is sandy and level, the Horizon
* is as fit for astronomical Observations as the Sea, and appears,
* at a small Distance, to be no less a Collection of Water1. It was
* likewise equally surprizing, to observe, in what an extraordinary Manner
* every Object appeared to be magnifyed within it; insomuch that a Shrub
* seemed as big as a Tree, and a Flock of Achbobbas might be mistaken
* for a Caravan of Camels. This seeming Collection of Water, always
* advances, about a Quarter of a Mile before us, whilst the intermediate
* Space appears to be in one continued Glow, occasioned by the quivering
* undulating Motion of that quick Succession of Vapours and Exhalations,
* which are extracted by the powerful Influence of the Sun." [pp.378-379]
* P.378 footnote at "Water": "The like Observation is taken notice of
* by Diodorus Siculus in his Account of Africa, l. 3, p. 128" -- and the
* passage is quoted in the original Greek.
* This theme is continued in the Supplement, which is dated 1746;
* pp. vi and vii of its Preface contain a Note to p. 378:
* "To Note 1. add this learned Remark, and corroborating Proof,
* from Dr. Hyde ; who in his Annotations on Peritsol's Itinerary,
* p. 15 deduces the Name of Barca and Libya , from this Phænomenon .
* [Quotation italicized in the original:] Et quidem (ut denominationis
* causam & rationem exquiramus) dictum nomen [Arabic transcription]
* [Hebrew transcription] splendorem seu splendentem regionem notat,
* cum ea regio radiis solaribus tam copiose collustretur, ut reflexum
* ab arenis lumen adeo intense fulgens, a longinquo spectantibus (ad
* instar Corporis Solaris) aquarum speciem referat; & hicce arenarum
* splendor & radiatio Arabibus dicitur [Arabic] serâb i.e. aquæ
* superficies , seu superficialis aquarum species . --- Hinc etiam
* nominis [Greek] ratio peti potest - cum [Hebrew] contractum sit pro
* [more Hebrew], a [Hebrew] flamma - a fulvescentibus arenis ardore
* pene inflammatis."
* The full title of the Supplement is: A Supplement to a Book Entituled
* Travels, or Observations, &c. wherein Some Objections, lately made
* against it, are fully considered and answered: with several additional
* Remarks and Dissertations."
* The long s is used throughout; curious spellings such as "antient"
* are regularly used. Note the capitalized Nouns as well. . . .
* Note that Jefferson's editor (William Peden) appears to have mis-read
* the page reference from TJ's MS note: it is 362, not 302.
* EARLY LOOMING (cited by Cranz)
* "Fuer einen gewissen Vorboten eines bevorstehenden großen Sturmes in
* der See, oder auch in den unteren Gegenden des Jenisei wird dieses
* gehalten, wenn Inseln oder jaehe Felsen, die bey stillem Wetter niedrig
* aussehen, groeßer als gewoehnlich zu seyn scheinen."
* NOTE: the umlauts are written as a small letter e over each vowel.
* FIRST appearance of "MIRAGE" in print? (1753)
* Chabert's full account: the 'mirage' explanation is on p. 136.
* It is taken from his journal entry for 23 Juin 1751, when he was
* observing:near Cape Sable (the southern tip of Nova Scotia).
* "Je m'occupai pendant trois jours à la suite des opérations de la
* carte, commencées le 23 à la pointe du cap, & dans lesquelles je fus
* souvent arrêté par l'effet du mirage . C'est ainsi que plusieurs
* marins appellent un changement qui, quelquefois se fait en apparence
* dans l'aspect des côtes un peu éloignées, parce qu'ils l'attribuent
* à la réflexion du ciel, qui se peignant dans la mer au dessous de la
* côte, fait paroitre cette côte comme élevée dans le ciel. Ce même
* phénomène semble bien plûtôt venir de la grande réfraction à
* laquelle sont sujets les objets vûs à travers des vapeurs fort denses :
* cette densité n'étant point égale dans toute l'étendue d'une côte,
* les rayons diversement brisés la rendent méconnoissable. C'est la
* raison qu'en a donné feu M. Maraldi, dans les Mémoires de l'Académie
* de l'année 1722."
* The remark about the mirage stopping his surveying operation is
* very similar to the report by Boscovich & Maire (1755). Notice that in
* this version, the word comes from "several sailors"; in the abstract in
* "Hist.", the word is attributed to "the inhabitants" of the coast.
* This page is cited in the Index as a peculiar entry: "Mirage. Idée
* de cette illusion d'optique, 136."
* Note that Bouguer was one of the referees who approved this work for
* publication (pp.i and iv).
* The first page has a nice woodcut showing the surveyors with all their
* equipment, observing the Moon with their quadrant to determine the time.
* This was reprinted in 1966; copies of the original sell for over $1000.
* Available at Google Books. The example digitized by Google bears the
* stamps of the National Library of Naples.
* https://www.google.com/books/edition/Voyage_fait_par_ordre_du_roi_en_1750_et/lJzIEAa6cuwC?hl=en&gbpv=1&dq=mirage&pg=PA136&printsec=frontcover
* ROGER BOSCOVICH sees some EARLY INFERIOR MIRAGEs, and looming
* The mirage observations are in paragraphs 173 and 174.
* These seem to be the first circumstantial descriptions of mirages.
* To understand para.173, some explanation is required:
* They were starting the triangulation at the mouth of the Ausa river
* (near Rimini) in July, 1752, using a baseline measured along the shore
* some months previously. The "sign" used at each end of the baseline
* was three posts stuck in the ground, with a whitewashed sheet wrapped
* around their upper ends as a target to sight on. The angles were
* measured with a portable quadrant. Now read on:
* "As soon as the signs were erected, we went there to take angles, and
* at least at the Ausa's mouth everything went quite well. But as soon as
* we reached the other end, a quite wonderful phenomenon appeared to us.
* The second sign is separated from the first by only eight thousand
* paces [about 12 km in modern units], and more than 20 spans [1.5m] high;
* we had seen it quite plainly first thing in the morning. But when we
* arrived at this second end a little after noon, allowing for the
* curvature of the sea (for a straight line about eight miles long joining
* the two heads would pass well above the sea) could only hide much less
* of its height in this interval, for it was raised 20 spans; yet now with
* the telescope pointed to a place we knew very well, corresponding to
* a place at the port of Rimini next to the building where those who are
* accustomed to be cared for are liberated to health from a fear of
* pestilence [i.e., the quarantine hospital], nothing appeared at all.
* Really only the highest part of the buildings was seen, and even that
* wonderfully contracted, as also the sails of ships in the harbor, many
* of which were spread and appeared completely distorted. Struck by the
* novelty of the thing, I brought a ladder to the post of the sign, and
* having climbed up a few steps, with the telescope pointed to the place,
* I saw the webbing of the sign at Ausa, not emerging from the waters
* gradually, though it was broad, but all at once, at first as through a
* haze, then much clearer, and at first the thinnest line, then as I
* climbed higher it enlarged more, until it returned to its own form,
* as did that building I have mentioned, and the sails of the ships. Both
* Maire and I have watched this phenomenon quite astonished, again and
* again, now raised up higher by the steps, now lowering the eye; but toward
* sunset we had to return to our angles, which we could take even at this
* sign, by moving a wagon, which fortunately was there, to the very place of
* observation, and raising up the quadrant in it, we saw the sign quite
* plainly, and we completed our observations."
* [This is a fine description of an inferior mirage; the "all at once"
* business being a particularly nice touch; cf. Hardcastle (1905).]
* In para.174, he remarks that he has often seen "the ends of
* promontories, or the points of islands, as if raised in the air," and
* that this is a phenomenon of the same kind. He has noticed that this
* occurs only when the line of sight grazes the surface of the sea, and
* that it vanishes if viewed more obliquely from a higher location.
* In section 175, he mentions an instance of variable looming, which he
* correctly attributes to an "inequality" of the horizontal refraction.
* Thanks to Classics Prof. James Smith for assistance with the translation!
* According to the E.B., Christopher Maire was an English Jesuit.
* O'C #9
* Early use of the word "MIRAGE" by Joseph-Bernard de Chabert
* "Cette année M. de Chabert, Lieutenant des vaisseaux du Roi, Chevalier
* de l'Ordre de Saint-Louis, Membre de l'Académie de Marine, de celle de
* Berlin & de celle de l'Institut de Bologne, présenta à l'Académie la
* Relation du voyage qu'il a fait par ordre du Roi en 1750 & 1751 dans
* l'Amérique septentrionale, pour rectifier les cartes des côtes de
* l'Acadie, de l'isle Royale & de celle de Terre-Neuve, & pour en fixer
* les principaux points par des observations astronomiques." (pp.242-243)
* "Pendant que M. de Chabert étoit occupé à lever les plans dont nous
* venons de parler, il fut souvent arrêté par un phénomène singulier,
* qu'on appelle mirage : c'est un changement apparent de l'aspect des
* côtes un peu éloignées, que les habitans attribuent à la réflexion du
* ciel, qui, se mirant dans l'eau, fait paroître la côte comme élevée
* en l'air, & que M. de Chabert croit, avec plus d'apparence, causé
* par l'irrégularité de la réfraction qu'ont souvent à souffrir les
* objets terrestres." (p. 253)
* (See Gronier, 1961, for a good translation.)
* From the collected tables of contents, it appears that this text is
* on p.358 of the reprinted edition of Hist. Acad. Roy. Sci.
* This account in the Hist. Acad. Roy. Sci. is just an extended abstract
* of the book published in 1753.
* Many thanks to Éric Frappa for discovering this at Gallica:
*
* http://gallica.bnf.fr/ark:/12148/bpt6k3551g/
* DOMENICO GIARDINA explains the Fata Morgana of Aug. 1643
* The day here (the 14th) is the day before Angelucci's FM observation
* quoted by Kircher (1646); but the two accounts are substantially
* identical, as noted by Consolo; Allegranza seems to be the only source
* for the 14th as the date.
* [Cf. Boccara's (1902) denunciation of Kircher, Giardina, and Allegranza.]
*
* The motivation for publishing all this nonsense seems to have been the
* ambition of the publisher, Gioachimo Pulejo, a printer in Catania who
* published several works promoting the reputations of local cities and
* their inhabitants -- e.g., "L'ardenza e tenacità dell'impegno di
* Palermo, nel contendere a Catania la gloria di aver dato alla luce la
* regina delle vergini, e martiri siciliane Sant'Agata" (1747). The
* present case is another example: in the dedication, and on the prefatory
* pages I and II, "from the publisher to the reader", we see how he
* is concerned with promoting Sicilian works.
*
* The full title preceding Giardina's text is:
*
*
* D I S C O R S O
*
* S O P R A
* L A
*
* F A T A M O R G A N A
*
* DI MESSINA, COMPARSA
* NELL' ANNO MDCXLIII. AL DI XIV. D'AGOSTO
*
* DEL
* P. DOMENICO GIARDINA
*
* DELLA COMPAGNIA DI GESU'
*
* CON ALCUNE NOTE
* DELL' ERUDITISSIMO
* SIG. ANDREA GALLO
* MESSINESE.
*
*
* (which takes up all of p. 117.)
*
* Giardina and Gallo are briefly described in pp. II and III of the preface.
* As Giardina died in 1747, in his 50th year, he could not have observed
* the 1643 display he tries to interpret here; Marina Warner is confused.
* Unfortunately, her confusion has become a "viral" sensation on the Web.
* This falsehood continued to be spread by other readers who believed the
* fabrications added to the story by Capozzo (1840), such as Consolo
* (1993) and Séstito (2011).
*
* The numerous informative footnotes were inserted by Gallo; they refer to
* "the author" (Giardina) in the third person.
* In particular, note [c] (p. 121) criticizes the author for not being
* "concordant with modern Philosophy" which distinguishes the real ascent
* of sulfurous and bituminous material in the air from the "apparent,
* formed by the refraction of the solar rays."
*
* Giardina's essay ends on p. 143, where a letter from Giuseppe Allegranza
* begins. Allegranza attempts to derive "Morgana" from the German "Morgen".
* Strangely, he has the page wrong in "Ars Magna", and calls Angelucci
* "Andreucci". In fact, the page number given (704) corresponds to the
* 1671 edition published in Amsterdam in; but that one still has
* "Angelucci" correctly. Apart from minor editorial changes in spelling
* and punctuation, Allegranza's text here is exactly the same as a text
* published without attribution in "Giornale de' Letterati" for the year
* 1755, dated "Messina 15. Feb. 1751", pp. 46 - 55. In particular, both
* that version and this one have the "Andreucci" error. So Allegranza's
* 1751 text appears to be the origin of both the "Andreucci" error and the
* dubious date: he says the observation was made "in una Vigilia dell'
* Assunzione" -- i.e., the 14th. (p. 144) Boccara (1902) dismisses all
* of them: Kircher, Giardina, and Allegranza.
*
* The attribution of the Fata Morgana to reflections by "polyhedral
* crystals" seems to be inspired by Mariotte's explanations of halos
* by refraction and reflection in ice crystals, in 1679.
*
* Available in two copies from Google Books. One, from Oxford:
* https://books.google.com/books?id=3r0TAAAAQAAJ&vq=Giardina&source=gbs_navlinks_s
* is lower quality; the other, from U.Michigan:
* https://books.google.com/books/about/Opuscoli_di_autori_Siciliani_Dunning.html?id=LvgDAAAAMAAJ
* has had the name "Dunning" unaccountably appended to the title, and is
* also available at the HathiTrust site. Note that Vol. 2 is bound
* together (and scanned) with Vol. 1.
* This is the work Brydone (1773) mentions but was unable to find.
* Cited by P&E in a footnote on p.186.
* MARINA WARNER's garbled account (placed here for her citation of Giardina)
* Chapter 7 is devoted to "Fata Morgana ; or, Castles in the Air".
* Her Fig. 9b on p. 94 was the best reproduction of Fortuyn's engraving for
* Minasi that I had seen in print, until Séstito's (2011). But she failed
* to get the facts right:
* "Kircher described one instance in his book . . . , in response to a
* fellow Jesuit who had written to him [sic!] . . . about a . . . fata morgana
* he had witnessed himself in Sicily [sic!]." (p. 95)
* So she confuses Giardina with Angelucci, and Kircher with Sanzio.
* "Giardina . . . goes on to describe how he saw [sic] `a city all floating
* in the air . . .'" (p. 96)
* Note 2 on p. 96 links to p. 391; the note there cites both Giardina
* and Minasi -- who explained that Giardina was referring to Angelucci.
* She also parrots much common nonsense about mirages: "Technically
* now known as a `superior' or `looming mirage', fata morgana appears
* above the horizon, often rising to great heights among the clouds." (p. 97)
* Then follows: "Layers of the atmosphere at different temperatures develop
* [sic] different densities, and the sun's rays, hitting the surface
* of the sea and the layers of air at a certain angle (45 degrees) turn
* them into an infinite recession of mirrors, multiplying and inverting
* reflections, diffracting [sic] and refracting the light so as to project
* images of far distant scenes and objects onto the clouds; these images,
* turned upside down and superimposed [sic] on one another, then mingle
* and change rapidly as the layers move up and down from the observer's
* vantage point." Well, this is all nonsense! She has thrown some words
* together without understanding their meaning, and produced gibberish.
* On top of this, she cites as references on fata-morgana mirages some
* so-so websites, rather than the standard references on these topics
* (e.g., P&E; Humphreys; not even Minnaert or Greenler are cited.)
* A pretty sorry showing.
* (snippet view on Google Books)
*
* Much of this is taken from her Tanner lecture in 1999; see
* http://tannerlectures.utah.edu/_documents/a-to-z/w/Warner_01.pdf
* [all reprinted in Raritan 21, No.4, pp. 264-301 (Spring, 2002)]
* where she cites both Giardina and Minasi in note 3 on p. 67. There,
* she explicitly refers to Angelucci's letter in Kircher's book, and even
* says that Giardina's "Discorso" came "More than a hundred years later".
* So how did she later arrive at the wrong chronology?
* Note that her Tanner lecture contains more errors of its own; e.g.,
* her mistranslating of the phrase "delle sustruttioni di Salomone" as
* "the somersaults of Salome" instead of "the constructions of Solomon."
* This "Salome" appears as a typo in the text of the 1671 Amsterdam
* edition of "Ars Magna"; apparently she got it from that:
* https://books.google.com/books?dq=Kircher+%22Ars+Magna%22&jtp=704&id=wYlDAAAAcAAJ#v=onepage&q=Kircher%20%22Ars%20Magna%22&f=false
* -- and she gave 1646 as the date of Kircher's book, but cited the page
* (701) where this error appears in the 1671 edition. Evidently, she
* only consulted the later edition, citing the earlier one without
* actually reading it.
* Furthermore, she attributes Minasi's term "l'iride fregiata" (1773)
* to Giardina, who died in 1747, when Minasi (born in 1736) was still a
* schoolboy. (Giardina used "iride", but only in the phrase "iride
* marina".) And she mis-translates Minasi's phrase as "the festooned
* rainbow." Some historian!
* [And in the introductory Acknowledgments in the book, she gives the date
* of her 1999 lecture as 1992.]
* ARCHANGIOLO LEANTI's mention of Fata Morgana, based on Giardina
* This is the source of Brydone's (1773) exaggerated account.
* Although modern references to Leanti spell his given name "Archangelo",
* his historical monograph uses "Archangiolo" consistently. The title
* page describes him as "sig. Abate Arcangiolo Leanti da Palermo".
* The reference to the Fata Morgana is on pp. 3 and 4; he cites mainly
* the Giardina/Gallo/Allegranza work, but mentions Kircher, Fazello,
* Pliny, and Pomponius Mela as earlier sources.
* BOSCOVICH translated into French
* The same section numbering is used as in the original. There is a
* detailed map included, showing the region surveyed.
* NOTE on UNITS: There is a handy Table for converting between
* Roman feet and palms and Paris toises and feet on p. viii.
* Typographical note: The use of the accented "E" is extremely
* haphazard. On the title page, it only occurs in "État". In the
* preface and table of contents, no uppercase E is accented; but the
* lowercase é is abundant. The heading on p.1 of the main text says
*
* V O Y A G E
*
* ASTRONOMIQUE ET GÉOGRAPHIQUE
*
* DANS L'ÉTAT DE L'ÉGLISE
*
* and the body type all has accents where you'd expect them.
*
* See
* https://gallica.bnf.fr/ark:/12148/bpt6k9629131h/f25.item.texteImage
* John Byron's probable superior mirage
* Nov. 12, 1764: "At 4 PM it thunder'd & Lightened very much, & looked
* very black almost round the Horizon, I was then walking the Quarter Deck
* when all the People upon the Forecastle called out at once Land right a
* head, I looked under the Foresail & upon the Lee Bow, & saw it to all
* appearance as plain as ever I saw Land in my life, It made at first like
* an Island with two very scraggy Hammocks upon it, but looking to Leeward
* we saw the Land joining it & running along way to the SE, we were then
* steering SW. I sent Officers to the Mast head to look out upon the
* weather Beam & they called out immediately they saw the Land a great way
* to Windward. I brought too & sounded & had 52 fm -- I now thought I was
* embay'd & as it looked very wild all round I wished myself out before
* night. We made Sail & steered ESE. All this time the appearance of the
* Land did not alter in the least, the Hills looked very Blue as they
* generally do at some little distance in dark rainy weather, & many of the
* People said they saw the Sea break upon the Sandy Beaches. After steering
* for about an hour, what we took for Land all at once disappeared to our
* great astonishment, & certainly must have been nothing but a Fog Bank.
* Tho' I have been at sea now 27 years & never saw such a Deception before,
* & I question much if the oldest Seaman breathing ever did, except it was
* some in that Ship when the Master made Oath of seeing an Island between
* the West End of Ireland & Newfoundland, & even distinguishing the Trees
* upon it, & which since has never been heard of tho' Ships have been sent
* out on purpose to look for it. And had the weather come on very thick
* after the sight we had for some time of this Imaginary Land so that we
* could not have seen it disappear as we did, I dare say there is not a Man
* on board but would have freely made Oath of the certainty of it's being
* Land. Course So 47° Wt. Dist 108 Ms Latt in 43° 46' So.
* Longde made 19° 47' Wt."
* Note the reference to (evidently) "St. Brendan's island".
* [mentioned in Beauford's 1802 review of mirages.]
* VERY EARLY MIRAGE seen by David Cranz (FATA MORGANA + SUPERIOR MIRAGE)
* "Aber nichts hat mich mehr surprenirt und artiger anzusehen geduenkt,
* als wenn bey heiteren, warmen und stillen Sommer-Tagen die Kookoernen,
* oder die zwey Meilen von Godhaab gen Westen gelegenen Inseln, eine ganz
* andere Gestalt, als sie natuerlich haben, vorstellen. Nicht nur sieht man
* sie, wie durch einen Tubum , weit groesser, und alle Steine und die mit
* Eis angefuellten Ritzen so deutlich, als ob man nahe dabey stuende;
* sondern wenn dieses eine Weile gewaerht hat, so sehen sie alle wie ein
* einiges Land aus, und stellen einen Wald, oder eine geschorne Baum-Wand
* vor. Darauf sieht man sie allerley seltsame Figuren, als Schiffe mit
* Segeln, Wimpeln und Flaggen, alte Berg-Schloesser mit ruinierten Thuermen,
* Storch-Nestern und hundert dergleichen Dingen, vorstellen, welche sich in
* die Hoehe oder Weite ziehen und sodann verschwinden. Die Luft is alsdann
* zwar ganz still und klar, aber doch, wie bey sehr heissem Wetter, mit
* subtilen Duensten angefuellt, durch welche sich, nach meinen Gedanken,
* wenn sie zwischen dem Auge und den Inseln in einem gehoerigen Abstand
* sich befinden, die Objecte, wie durch ein convexes Glas, weit groesser
* vorstellen; und gemeiniglich folgt ein paar Stunden darauf ein sanfter
* West-Wind mit einem sichtbaren Nebel, da dann dieser Lusus naturae
* gleich ein Ende hat.(*)"
* FOOTNOTE: "(*) Etwas dergleichen habe ich bey Bern und Neufchatel von
* denen gegen Sueden gelegenen Gletschern observirt. Wenn sich dieselben
* naeher, deutlicher und groesser als gewoehnlich vorstellen, so rechnet
* der Landmann auf einen baldigen Regen, der sich auch gemeiniglich den
* folgenden Tag einstellt. Und die Tartern an der Muendung des
* Jenisei-Flusses in Sibirien haltens fuer einen Vorboten des Sturms, wenn
* die Inseln groesser scheinen. Gmelins Reise Th. III S. 129."
* Orthographic note: All double-s's are simply spelled out, using the long
* s for both. Umlauts are written as a raised e over the vowel.
* HUGH HAMILTON
* Early mirage publication (mentioned by Huddart.)
* Footnote, pp.43-44: "This Fleece of vapourous Air that some times hangs
* over Water, is very discernable when we stand by the Sea-side in a hot
* calm Day, and is the Cause of some odd Appearances. For the lower Part
* of the Air, which is then much impregnated with Water, refracts the Rays
* of the Light more strongly than at other Times, and by this unusual Degree
* of Refraction, Houses on the Shore at a Distance from us appear almost as
* high as Steeples, remote Ships and Islands and the extreme Parts of
* Head-lands or Promontories appear to be raised quite out of the Water, and
* to hang in the Air above its Surface."
* WILLIAM WALES reports looming in "haze" (i.e., "FOG") at Hudson's Bay
* Observations of LOOMING, CONCAVE surface, NEGATIVE DIP, etc.:
* pp. 115-116: "August 7th. About 5 saw the low land of Cape Churchill,
* bearing from the S to S. W. b. S. but the haziness of the horizon made
* the land put on a different appearance every 4' or 5'. I cannot help
* taking notice of one circumstance, as it appears to me a very remarkable
* one. Though we saw the land extreamly plain from off the quarter deck,
* and, as it were, lifted up in the haze, in the same manner as the ice
* had always done; yet the man at the mast head declared he could see
* nothing of it. This appeared so extraordinary to me, that I went to the
* main-top-mast-head myself to be satisfied of the truth thereof; and though
* I could see it very plain both before I went up, and after I came down,
* yet could I see nothing like the appearance of land when I was there.
* I had often admired the singular appearance of the ice in these parts,
* which I have seen lifted up 2° or 3° at a distance of 8 or 10 miles,
* although when we have come to it, we have found it scarcely higher than
* the surface of the water."
* P. 131: "The prodigious difference between the latitude of Churchill
* factory, as laid down from observations made by Hadley's quadrant, and
* that deduced from the observations made with our astronomical quadrant on
* shore, has often employed my most serious attention; but I cannot think on
* any probable cause for such difference, unless it lie in the very great
* refractive power of the air in these parts. I have mentioned how the
* ice and land appear to be lifted up, when we stand on the ship's deck:
* and if the visible horizon be lifted up in like manner, it must make its
* apparent distance from the sun, or, which is the same thing, the sun's
* apparent altitude less than it otherwise would be; and consequently,
* the latitude greater than the truth; and also greater than it will be
* shewn by a land quadrant, which depends not on the horizon, agreeable
* to what we find it in the case before us*."
* The footnote (*) continues onto p. 132:
* "*Having mentioned this circumstance to the reverend Mr.
* Maskelyne, it immediately occurred to him, that the longitude
* deduced from observations of the moon’s distance from the sun or a
* star, would be considerably affected by this cause, as not only
* the altitudes of the sun, from whence the time at the ship is
* found ; but also the latitude of the ship, found by an observa-
* tion of the sun’s meridional altitude, or otherwise, will conspire
* to encrease the sun’s distance from the meridian, or angle at the
* pole.
* "I have therefore recomputed the longitude from my observa-
* tion of the moon's distance from the sun, taken August the 5th,
* 1768, on a supposition that the mean error in any altitude taken
* by Hadley's quadrant, arising from this cause, is 10 minutes;
* and find that, on such a supposition, which it must be allowed
* appear to be extremely well founded, the longitude will be 11'¼
* less than what I found it at the time when I made the observa-
* tion, and therefore the longitude of Churchill will in this case be
* only be 94° 30'¾ W. And by making a similar correction of 15' to
* Mr. Dymond’s observation of the 6th, it will give the longi-
* tude of Churchill 95° 18' W." [Modern long. = 94° 13'.]
* [This may be the EARLIEST mention of this problem.]
* William Wales later made similar observations in the Antarctic, as
* one of the astronomers on Captain James Cook's second voyage. A good
* biography is at
*
* http://biographi.ca/009004-119.01-e.php?id_nbr=2203
*
* and a complete bibliography of his publications is at
*
* http://www.captaincooksociety.com/home/detail/articleid/95/manuscripts-and-published-work-involving-william-wales
*
* Available from JSTOR; but their OCR is worse than tesseract's.
* Their URL is
* http://www.jstor.org/stable/105882?seq=1#page_scan_tab_contents
* JOSEPH VIERA Y CLAVIJO (1772) -- Early mirage observations in CANARIES
* After recounting the legend of the mythical island, and quoting some
* first-hand observations, he concludes it is all due to atmospheric
* refraction.
* The mirage section is unusually long and detailed. It is Chapter 28 of
* Book 1.
* (Originally published by La Imprenta de Blas Roman, Madrid, 1772-1783)
* Thanks to Guy Vincent for calling this to my attention!
* PATRICK BRYDONE's account of the Sicilian mirages
* Though this is clearly a description of the Fata Morgana, that name
* never appears; instead, the apparitions are attributed to Old Nick
* [Note: "this place" is Messina]:
* "Do you know, the most extraordinary phœnomenon in the world is often
* observed near to this place? -- I laugh'd at it, at first, as you will do;
* but I am now thoroughly convinced of its reality; and am persuaded too,
* that if ever it had been thoroughly examined by a philosophical eye,
* the natural cause must long ago have been assigned.
* "It has often been remarked, both by the antients and moderns, that
* in the heat of summer, after the sea and air have been greatly agitated
* by winds, and a perfect calm succeeds, there appears, about the time of
* dawn, in that part of the heavens over the Straits, a vast variety of
* singular forms, some at rest and some moving about with great velocity.
* These forms, in proportion as the light increases, seem to become more
* aerial; till at last, some time before sun-rise, they entirely disappear.
* "Some of the Sicilian authors represent this as the most beautiful
* sight in nature; Leanti, one of their latest and best writers, came here
* on purpose to see it: He says, the heavens appear crowded with a variety
* of beautiful objects: He mentions palaces, woods, gardens, &c. besides
* the figures of men, and other animals, that appear in motion amongst
* these objects. -- No doubt the imagination must be greatly aiding, in
* forming this aerial creation; but as most of their authors, both antient
* and modern, agree in the fact, and many give an account of it from their
* own observation, there certainly must be some considerable foundation
* for the story. There is a Jesuit, one Giardina, that has lately writ
* a treatise on this phœnomenon, but I have not been able to find it:
* The celebrated Messinese Gallo has likewise published something on this
* singular subject; if I can procure them in the island, you shall have
* a more perfect account of it. The common people, according to custom,
* give the whole merit of it to the devil; and indeed it is by much the
* shortest and easiest way of accounting for it: Those who pretend to
* be philosophers, and refuse him this honor, are greatly puzzled what
* to make of it. They think it may be owing to some uncommon refraction,
* or reflection of the rays, from the water of the Straits; which, as it
* is at that time carried about in a variety of eddies and vortexes, must
* of consequence, say they, make a variety of appearances on any medium
* where it is reflected. -- This, I think, is nonsense; or at least very
* near it; and till they can say more to the purpose, I think they had
* much better have left it in the hands of the old gentleman. I suspect
* it is something in the nature of our Aurora Borealis; and, like many of
* the great phœnomena of nature, depends upon electrical causes; which,
* in future ages, I have little doubt, will be found to be as powerful an
* agent in regulating the universe, as gravity is in this age, or as the
* subtile fluid was in the last." (Vol. I, pp. 86-89)
* (Brydone's scientific specialty was electrical phenomena.)
* NOTE: Brydone's comments on Leanti are off the mark: Leanti was born
* in Sicily, and spent his whole life there; so the ". . . came here on
* purpose to see it" part is bogus [he probably confused Leanti with
* Kircher in this case]. Likewise, "the heavens appear crowded with"
* the images is Brydone's invention; Leanti merely says "in the air".
* [Brydone's references to Giardina and Gallo correspond to Gallo's
* notes added to Giardina's useless rediscussion of Angelucci's letter.]
* This went through dozens of editions, in English and several other
* languages. In the "new edition" of T. Cadell and W. Davies (1806), the
* text has been tidied up a bit by minor editing, and changes in punctuation
* and spelling (making "ancients" and "phænomenon" instead of the variants
* above, for example); and the passage then falls on pp. 50-52.
* I read somewhere that this originally appeared in the Gentleman's Magazine
* in 1773, but find no reference to it.
* Copies of the 1773 London (1st) and 1806 editions are on Google Books.
* ANTONIO MINASI's account of the Fata Morgana
* There are many interesting details here that were omitted by Nicholson
* in his translation. This 102-page monograph is more informative than
* some later reviews (Nicholson; Reinecke; Büsch; Gilbert; P&E) suggest.
* The last 4 all depend on German translations of Nicholson's English.
* In the footnote on p. 18, he says "I have observed a little Fata
* Morgana near Rome. . . " at 11:30 on April 21, in the lake of Castel
* Gandolfo.
* In the discussion, he reviews all earlier accounts, including de
* Ferrariis, Angelucci, Kircher, etc. -- even including the Maccabees.
* He reprints (with some minor changes) almost all of Angelucci's letter,
* from the 1671 (Amsterdam) edition of Kircher.
* Notice his extensive discussion of Giardina's paper (§4, pp. 21 ff.)
* Minasi makes plain his disbelief of the Giardina discussion in Cap. IV;
* see the additional discussion in his footnotes 2 and 7 to this chapter.
* See his footnotes on p. 35, and the derivation of the "45°" on p.41.
* Minasi buried much valuable information in his footnotes. For
* example, the note on p.17 in Cap. III mentions the "spring, and the
* first months of summer" as the time when the images are reflected;
* and these are exactly the classical superior-mirage season (cf. Forel!)
* And on the next page, he cites the months of April through August as
* most favorable for these reflections.
* Note that Minasi's footnotes are numbered consecutively on each page .
* This leads to some confusion in their cross-references: the note at the
* foot of p. 17, where § 8 begins, is actually referenced in § 7, and
* numbered 1. The "nota 1" of § 8 that is referenced in the notes in
* later chapters is the note numbered 1 on p. 18, but continued on p. 19.
* The next note, cited as "§8. nota 2" in later chapters, is numbered 1 on
* p. 19, but continues on p. 20.
* Note on UNITS: the "Italian palms" used by Minasi are probably the same
* as the "Roman palms" that are converted to Paris measures in the Table on
* p. viii of the 1770 French translation of Maire & Boscovich.
*
* This is available at Google Books:
*
* https://books.google.com/books?id=yh3SLkLf9NYC&printsec=frontcover&dq=Minasi+%22Fata+Morgana%22&hl=en&sa=X&ved=0ahUKEwi_-vuR3f7dAhWlct8KHSiCCCIQ6AEILDAB#v=onepage&q=Minasi%20%22Fata%20Morgana%22&f=false
*
* but unfortunately the text of the PDF file they provide is badly
* garbled. Apparently, because of the mixture of Italian, Latin, Greek,
* and Hebrew in the text, everything available in UTF-8 encoding turns up.
* There are snatches of Chinese and Japanese characters, as well as
* Cyrillic. This makes any kind of machine translation impractical.
* A more practical re-publication of Minasi's text is in Consolo's
* 1993 book "Vedute dello Stretto di Messina"; but that is marred by
* his credulous acceptance of Capozzo's (1840) fallacious inventions.
* (Evidently, Consolo never bothered to read Minasi.) Yet another
* republication of Minasi's text is in Séstito's book (2011); it copies
* errors from Consolo, and appears to be copied from his version rather
* than from Minasi's original.
*
* A high-resolution scan of Fortuyn's engraving is available at
*
* http://dr.casanatense.it/drviewng.html#action=jumpin;idbib=1582;idpiece=-1;imageNumber=1;idpiece=-1
*
* [click on the "IIP" icon in the header to see the full resolution.]
*
* The engraving is discussed in Maria Toscano's thesis:
* http://www.fedoa.unina.it/777/1/Tesi_Toscano.pdf
* and in her article:
* "Lo strano caso di Guglielmo Fortuyn. Un tentativo di attribuzione"
* Neoclassico, No. 23/24, pp. 39-68 (2003)
*
* Finally, a biography of Minasi written by Enrico Pescatore was published
* in the "Scilla News" on 20 April, 2020, and archived on the publisher's
* website:
*
* http://www.strettoweb.com/2020/04/scilla-storia-don-antonio-minasi/1003141/
*
* Possible mirages in the Antarctic in JOHN MARRA's Journal (1775)
* [Dec. 15, 1773:] "Here the ice islands presented a most romantic
* prospect of ruined castles, churches, arches, steeples, wrecks of ships,
* and a thousand wild and grotesque forms of monsters, dragons, and all the
* hideous shapes that the most fertile imagination can possibly conceive."
* (p. 111)
* [Jan. 26, 1774:] "At nine in the morning every body on deck imagined
* they saw land; and accordingly preparations were made for getting all
* things in readiness to cast anchor. At eleven crossed the antarctic
* circle to the southward for the 2d time, and hauled up S. E. by E. where
* they were persuaded land was. But to their great disappointment, the
* farther they sailed, the farther the land seemed to bear from them;
* and at length it wholly vanished." (p. 123)
* [Jan. 30, 1774:] "Came in sight of a fog bank, which had a great
* appearance of land, and many who were thought the best judges asserted
* that it was land; however it proved upon trial a deception, as well as the
* former. . . . Taking a view from the mast-head nothing was to be seen but
* a dreary prospect of ice and sea. Of the former might be seen a whole
* country as far as the eye could carry one, diversified with hills and
* dales, and fields and imaginary plantations, that had all the appearance
* of cultivation; yet was nothing more than the sports of chance in the
* formation of those immense bodies of congregated ice." (p. 125)
*
* This is a heavily-edited account, nowadays attributed to the journal of
* John Marra, a gunner's mate on the Resolution . Supposedly his editor
* was David Henry, of the Gentleman's Magazine . No author appeared
* on the title page of this when it was originally published, 18 months
* before Cook's official account (which does not mention these appearances,
* but only ice fields). The original title was:
*
* J O U R N A L
* of the
* RESOLUTION's VOYAGE,
* In 1772, 1773, 1774, and 1775.
* on
* DISCOVERY to the SOUTHERN HEMISPHERE,
* by which
* The Non-Existence of an undiscovered Continent,
* between the Equator and the 50th Degree of Southern
* Latitude, is demonstratively proved.
*
* Sources on the Web indicate that a French translation was published
* in Amsterdam in 1777, and it is evidently that which Biot had read.
* This modern edition is Bibliotheca Australiana #15.
* WALES & BAYLY (astronomers with James Cook's second voyage)
* William Wales was the editor of this volume, which contains various
* sections written by himself and by William Bayly; Wales was aboard
* the Resolution (James Cook's flagship); Bayly, on the Adventure.
* Our interest is in Wales's "Meteorological Journal", pp. 335-366.
* The excerpt reprinted by Sir Napier Shaw in 1930/1942 was from
* p. 351; cf. Pernter (1902).
* The publication details are complex: the volume was printed by
* W. & A. Strahan, and sold by J. Nourse, in the Strand, and J. Mount
* and T. Page, on Tower-Hill, Booksellers to the Board of Longitude,
* which paid for the observations:
* "Published by order of the Board of Longitude, at the Expence of which
* the Observations were made."
* See
*
* http://acms.sl.nsw.gov.au/album/albumView.aspx?itemID=852703&acmsid=0
*
* for the Introduction and Contents.
*
* LE GENTIL's observations in India
*
* There are several sections of interest here, all in the Seconde Partie
* of Vol. 1:
*
* Ch. I, Art. III. Observations sur les Réfractions horizontales (p. 393)
* Remarques sur l'Observation des Hollandois dans la nouvelle Zemble en
* 1596 & 1597 (p. 416)
* Ch. I, Art. IV. Observations sur les Réfractions, à différens
* degrés de hauteur (p. 426)
* Then, after the Supplément:
* Observations sur les Réfractions terrestres (p. 701)
*
* Full title:
* VOYAGE
* dans
* LES MERS DE L'INDE,
* FAIT PAR ORDRE DU ROI ,
* A l'occasion du Passage de Vénus,
* sur le Disque du Soleil, le 6 Juin 1761,
* & le 3 du même mois 1769.
*
* TOBIAS GRUBER's letter
*
*
* An amazingly perceptive summary of the salient points: flat, smooth
* ground; the hiding of objects below a limiting ray; the dependence
* on season, height of the eye and distance to the object --
* all here in just a few pages. P. 55 has a nice ray diagram, too.
* "Ein merkwürdiges Phänomen, welches ich auf meinen Reisen im
* Temeswarer Bannate so oft gesehen, und hier auf dem ebenen Seeboden
* samt meinen Gefährten wieder zu bemerken Gelegenheit hatte, kann ich
* unmöglich ganz vorbeylassen. Blos in sehr flachen, und auf viele
* Meilen weit sich erstreckenden Gegenden, besondere, wenn sich der
* ebene Horizonte in dem Himmel hinaus verliert, habe ich den über die
* Erde etwa 6 Schuh hoch liegenden Theil der Atmosphäre also verdicket
* gefunden, daß die unter einem sehr spitzigen Winkel darauf einfallenden
* Lichtstrahlen nicht durchgelassen, sondern abgeprellet werden; welches zu
* vielen optischen Blendungen Anlaß giebt. Also habe ich in einer Ferne
* von 1000 bis 2000 Klaftern blos die Dächer von Dorfgebäuden gesehen,
* welche mir wie ein durchsichtiges Wäldchen vorkamen. Also erschienen
* die hie und da auf der Ebene stehenden Warthügel ohne Grundlage.
* Also wurden die etwas höher emporragenden Objecte, als Bäume, Gebäude,
* Thürme, u. s. w. doppelt so hoch gezeigt, weil sie nämlich wie auf
* einer Wasserebene gespiegelt wurden. Also sah ich in der weiten Ferne
* zerstreute große Seen, die bis an den Horizont hinaus wie Meere wurden.
* Nach Maaß der Annäherung verschwanden sie, und entfernten sich immer.
* Ja so gar, wenn ich von meinem Sitze im Kalesche, wo ich sie noch sah,
* aufstund, und mich etwa 3 Schuhe in die Höhe richtete, so nahmen sie
* ab, oder erschienen nicht mehr. Als ich die Ursache dieses Spielwerkes
* der Lichtstrahlen noch nicht kannte, ward ich überdiemaßen durch diese
* Seltsamkeiten gerührt. Die öftere Ansicht in verschiedenen Umständen,
* das Erscheinen und Verschwinden nach Verhältniß der Erhöhung und
* Erniedrigung, und die Analogie aus optischen Experimenten entdeckten
* mir endlich das ganze Geheimniß." He explains it, with the use of the
* ray diagram. "Es ist eine ganz natürliche Sache, daß, wenn ein
* Lichtstrahl sehr schief in ein Mittelding einfällt, dessen Verdickung
* verhältnißmässig anwächst, derselbe den Grund des Mitteldings
* nicht erreiche, sondern in einer Entfernung vom Grunde, unter eben
* dem Winkel, unter welchem er einfiel, abgeprellet werde. Newton hat
* diese Eigenschaft bey allen spiegelnden Flächen aus der Theorie der
* abstossenden Kräfte erwiesen. Kommt nun die Direction ch vom Himmel,
* oder aus einer lichtgrauen Ferne, (wie es beym Zirknitzer See geschah,)
* so sieht man nichts von den Objecten, die unter der Linie ch stehen,
* und die reflektirte wird dem Wasser ähnlich seyn. . . .
* "Auf diese Art erklärte ich mir alle ähnliche Erscheinungen.
* Die Sache fordert aber eine nähere Bestimmung, zu welcher ich zu
* wenig Zeit für diesmal habe. Ueberhaupt scheine ich mir mit Grunde
* schließen zu können, daß die durch gröbere Dünste nahe an der Erde
* verdickte Luft (welches ich meistens im Frühjahr bemerkte) bloß auf
* einer gewissen Höhe über den weiten Flächen (vielleicht auf 6 bis 7
* Schuhe) diese optischen Betrügereyen hervorbringen könne."
* [The line ch mentioned is not Minnaert's "vanishing line," but the
* lowest ray of an erect image. Thus Gruber failed to appreciate that
* there are in fact bits along the way that lie above Biot's caustic but
* below this ray, and so are visible. He neglects the general curvature
* of the rays, as well as that of the Earth.]
* This is actually a Postscript (Nachschrift ) to the Fifth Letter,
* beginning on p. 40, and dated 20 April 1779, from Zirknitz.
* The "Kalesche" was an open horse-drawn carriage with a folding top,
* usually rendered as "calash" or "caleche" in English.
* Typographical note: this is all set in Fraktur, with little e's over
* the vowels as umlauts. There are numerous ligatures: ch, ck, ff, fi, fl,
* si, ss, st, sz, tz. ["Krausz" is actually set with the tz ligature,
* which differs from the ß used in "durchgelaßen" and "abstoßenden".]
* Proper names are set in a slightly broader and less angular font than
* the Fraktur body text.
*
* Full title page reads:
*
* Herrn Tobias Grubers,
* Weltpriesters und k. k. Bau- und Navigationsdirektors
* im Temeswarer Banat,
*
* B r i e f e
* hydrographischen
* und
* physikalischen Inhalts
* a u s K r a i n
* an
* Ignaz Edlen von Born,
* k. k. wirklichen Hofrath
*
*
* Available today at
*
* https://books.google.com/books?hl=en&lr=&id=zehnX5qi9YIC&oi=fnd&pg=PA3&dq=Grubers+Briefe+1781&ots=KZk9HfEjaY&sig=NspSHz-thBbqj_Tczwe-EBfI3Uk#v=onepage&q=Grubers%20Briefe%201781&f=false
*
* [Pogg. says "eigentlich Grüber."] See also Acta Carsologica 33,
* 277-298 (2004), available at
* http://www.zrc-sazu.si/izrk/Carsologica/Acta332/Pdf3332/juznic.pdf
* for more information about Gruber and his book.
* Ignaz von Born is profiled in European History Quarterly 36, 61 (2006);
* see
* http://ehq.sagepub.com/cgi/reprint/36/1/61.pdf
*
* Despite the name on the title page, this was often cited as written by
* Johann Gruber. There are also obscure references to a "patriotic"
* commentary on Gruber's letters, published the same year in Laibach.
* Joh. Georg BÜSCH's TRACTATUS DUO OPTICI ARGUMENTI (1783)
*
* Only the first 78 pages deal with mirages; the second "argument"
* of the tract is devoted to myopia -- which is how I discovered that
* the Becker Medical Library of Washington University (St. Louis) has
* a copy (see their website).
* The preface explains that he was inspired to write by the problem
* posed by the Royal Danish Academy of Sciences ("Societas Hafniensis")
* in 1781. He also says he has translated his observations into Latin to
* make them available to the learned societies.
* Here the "miles" are specifically German ones; and the barometric
* readings are explicitly in Paris inches and lines. Unfortunately,
* he scrupulously gives barometric readings, but no temperatures!
* On pp. 9 and 10, he discusses Fig. 1, which shows the difference
* between the apparently calm reflecting surface in the distance, and the
* surface roughened by the wind in the foreground. This effect is also
* shown in Figs. 3, 4, and 6 (discussed on pp. 16, 17, and 36).
* On p. 12, he notes that this mirage is more likely to be seen in the
* morning, with a clear sky, and warm air. And he does discuss the effect
* of changing the height of the eye.
* On p. 20 is the original "chamberpot" quotation in the original
* English: "Indeed, it looks like a Chamberpot turn'd upside down."
* The first 38 pages are observations; then comes his theory: he
* thinks it has to do with electricity, and lightning. . . . He also
* supposes that (because only distant objects are miraged) the curvature
* of the ray depends on distance. . . .
* Still, on p. 39 he says ". . . refractionem, quae indubia causa est,
* . . . "
* Interestingly, he does invoke total internal reflection (p. 53).
* But (p. 59) "there must be something by which the light is reflected."
*
* On p. 61, he quotes from Gruber's 1781 letter, translated from German
* to Latin. (For a while we have "Gruner" for "Gruber"; but the given
* name "Tobias" certainly identifies him, as well as the reference to
* Carniola; apparently Büsch confused Gruber with the Swiss naturalist
* and geologist G. S. Gruner, who also worked about that time.) Büsch
* discusses Gruber's letter extensively, saying at the outset that
* "hunc virum primum omnium praeter me phaenomenon integrum observasse."
* Büsch adds notes to Gruber's text -- perhaps his dissent from some
* of Gruber's remarks explains Gruber's later hostility toward Büsch.
* Notably, "Non in vaporibus causa est sita." (p. 68) But he thinks
* the air is always denser at the ground than higher up (p.70), and
* argues that that the denser air cannot separate from the lighter to form
* a visible surface, "like two immiscible liquors, such as terebinth oil
* [turpentine] and spirit of wine".
* He ends by offering advice to those who would investigate further:
* make observations in all seasons from a fixed place; use an instrument
* capable of measuring small angles; an achromatic telescope "for avoiding
* all confusion of the image that deceives the naked eye"; a level to
* observe "how much objects are raised and lowered for various conditions
* of the air". And it would also be useful, if convenient, to observe
* from the same place the Moon rising and setting over the sea. (pp.76-77)
* There is a table of Corrigenda on p. 132.
*
* Title page reads:
*
* Ioannis Georgii Büsch
* Math. Prof. Hamburgensis
* Tractatus duo
* optici Argumenti
* cum figuris.
*
* The internal title page of the first essay reads:
*
* I.
* Observata nova
* in
* refractione horizontali
* et inde nata
* mira imaginum reflexione.
*
*
* [Extracts were translated into German by Gilbert in 1800.]
* Special thanks to the ILL people for this one at last!
*
* This is now available at
* https://books.googleusercontent.com/books/content?req=AKW5QafMp1bX3Vg_h8zvgBFeb6uKD2tNk6E1B4k5Urt-Fk-7Tl15AWPzA5YL5Il7CeESrYwKzHj0Rv44UjJAgLTihElDz3hPUr80LxTqdV-mYcz5CltbsDZSmrM6-Nob7bdLDFa9xQl6wfZqB6J-2Ub0NtDCCXVBAuOmPuBThOkqdU1OaYmBJtmebweLhAO0ELIWoVbpA99UL91Sl2WLMhYn5gSrihV0IY33_OM8AD8BCbxUlSqNv4cbIexDe4PfkdJt_HCPaQaLFa2xtzXb111elMg1M5_s7Q
* It contains the figures, placed on the 94th page of the PDF, after
* the title page of the second "argument".
*
* HENRY SWINBURNE's description of the FATA MORGANA
* Our interest is in pp. 263-266 of Vol. 2 of the 1790 Second Edition;
* presumably this first appeared in 1785. Here is what he says:
* . . . "Messina rises out of the waves like a grand amphitheatre; and
* the Faro, lined with villages and towns, seems a noble river, winding
* between two bold shores.
* "Sometimes, but rarely, it exhibits a very curious phænomenon,
* vulgarly called La Fata Morgana *. The philosophical reader will find
* -------------------------------------------------------------------------
* [the footnote on p. 263 says: "The name is probably derived from an
* opinion, that the whole spectacle is produced by a Fairy or a Magician.
* The populace are delighted whenever the vision appears, and run about
* the streets, shouting for joy, -- calling every body out to partake of
* the glorious sight."]
* -------------------------------------------------------------------------
* its causes and operations learnedly accounted for in Kircher, Minasi,
* and other authors. I shall only give a description of its appearance
* from one that was an eye-witness. Father Angelucci is the first that
* mentions it with any degree of accuracy, in the following terms:
* ``On the fifteenth of August, 1643, as I stood at my window, I was
* ``surprised with a most wonderful, delectable vision. The sea that
* ``washes the Sicilian shore swelled up, and became, for ten miles in
* ``length, like a chain of dark mountains; while the waters near our
* ``Calabrian coast grew quite smooth, and in an instant appeared as
* ``one clear polished mirror, reclining against the aforesaid ridge.
* ``On this glass was depicted, in chiaro scuro , a string of several
* ``thousands of pilasters, all equal in altitude, distance, and degree
* ``of light and shade. In a moment they lost half their height, and
* ``bent into arcades, like Roman aqueducts. A long cornice was next
* ``formed on the top, and above it rose castles innumerable, all perfectly
* ``alike. These soon split into towers, which were shortly after lost
* ``in colonnades, then windows, and at last ended in pines, cypresses,
* ``and other trees, even and similar. This is the Fata Morgana , which,
* ``for twenty-six years, I had thought a mere fable.''
* "To produce this pleasing deception, many circumstances must concur,
* which are not known to exist in any other situation. The spectator must
* stand with his back to the east, in some elevated place behind the city,
* that he may command a view of the whole bay; beyond which the mountains
* of Messina rise like a wall, and darken the back-ground of the picture.
* The winds must be hushed; the surface quite smoothed; the tide at its
* height; and the waters pressed up by currents to great elevation in the
* middle of the channel. All these events coinciding, as soon as the sun
* surmounts the eastern hills behind Reggio, and rises high enough to form
* an angle of forty-five degrees on the water before the city, -- every
* object existing or moving at Reggio will be repeated a thousand fold upon
* this marine looking glass; which, by its tremulous motion, is, as it were,
* cut into facets. Each image will pass rapidly off in succession, as the
* day advances, and the stream carries down the wave on which it appeared.
* "Thus the parts of this moving picture will vanish in the twinkling
* of an eye. Sometimes the air is at that moment so impregnated with
* vapours, and undisturbed by winds, as to reflect objects in a kind of
* aërial screen, rising about thirty feet above the level of the sea.
* In cloudy, heavy weather, they are drawn on the surface of the water,
* bordered with fine prismatical colours."
* Evidently, Swinburne's account (largely translated from his mentioned
* sources) was the inspiration for a burst of interest in these mirages
* in the English journals. For the next 20 years, refraction phenomena
* were often compared to Swinburne's account, until Wollaston's (1803)
* introduction of the French term "mirage" (and Nicholson's longer
* translation from Minasi) superseded it.
* Google Books has the Second Edition (1790, 4 vols.) on-line.
* Apparently the passage above is on p. 365 of the first volume of the
* two-volume (first?) edition.
* THOMAS JEFFERSON's observations: notes the importance of DISTANCE
* " Having had occasion to mention the particular situation of Monticello
* for other purposes, I will just take notice that its elevation affords
* an opportunity of seeing a phænomenon which is rare at land, though
* frequent at sea. The seamen call it looming . Philosophy is as yet in
* the rear of the seamen, for so far from having accounted for it, she has
* not given it a name. Its principal effect is to make distant objects
* appear larger, in opposition to the general law of vision, by which they
* are diminished. I knew an instance, at York town, from whence the water
* prospect eastwardly is without termination, wherein a canoe with three
* men, at a great distance, was taken for a ship with its three masts.
* I am little acquainted with the phænomenon as it shews itself at sea;
* but at Monticello it is familiar. There is a solitary mountain about
* 40 miles off, in the South, whose natural shape, as presented to view
* there, is a regular cone; but, by the effect of looming, it sometimes
* subsides almost totally into the horizon; sometimes it rises more
* acute and more elevated; sometimes it is hemispherical; and sometimes
* its sides are perpendicular, its top flat, and as broad as its base.
* In short it assumes at times the most whimsical shapes, and all these
* perhaps successively in the same morning. The Blue ridge of mountains
* comes into view, in the North East, at about 100 miles distance, and,
* approaching in a direct line, passes by within 20 miles, and goes off
* to the South-west. This phænomenon begins to shew itself on these
* mountains, at about 50 miles distance, and continues beyond that as far
* as they are seen. I remark no particular state, either in the weight,
* moisture, or heat of the atmosphere, necessary to produce this. The only
* constant circumstances are, its appearance in the morning only, and on
* objects at least 40 or 50 miles distant. In this latter circumstance,
* if not in both, it differs from the looming on the water. Refraction will
* not account for this metamorphosis. That only changes the proportions of
* length and breadth, base and altitude, preserving the general outlines.
* Thus it may make a circle appear elliptical, raise or depress a cone,
* but by none of its laws, as yet developed, will it make a circle appear
* a square, or a cone a sphere."
* At the word "diminished", there is a note, which is apparently due
* to the editor, William Peden; it says: "MS note by TJ . Dr. Shaw in
* his Physical observations on Syria, speaking of the Easterly winds,
* called by Seamen Levanters, says `we are likewise to observe further
* with regard to these strong Easterly winds, that vessels, or any other
* objects, which are seen at a distance, appear to be vastly magnified,
* or loom , according to the mariners expression.' Shaw's travels, 302.
* Ed. note. Thomas Shaw (1674-1751), English traveller and educator,
* author of Travels or Observations Relating to Several Parts of Barbary
* and the Levant (Oxford, 1738)." [p. 280]
* N.B.: The page (302) that Peden attributes to TJ in this note is
* incorrect. The correct page number is 362. [Cf. Shaw, 1738.]
* This was written in 1781 and revised in 1782. Jefferson had a small
* edition privately printed in 1784 in Paris. A French translation
* appeared in 1786; the original English was published in 1787.
* The passage on "looming" appears on pp. 80-81 of the 1982 Norton
* paperback in our library, at the end of Chapter 7.
* Cited by Talman in his 1932 article in Yachting .
* Early mirages: Claims to have written to Abbe v. Herbert in 1776;
* cites his letter in 1781, published before Büsch's
* "Tractatus duo argumenti optici" of 1783.
*
* N.B.: "Klafter" = "die Länge des Menschens" (approx. 1.9 m)
* according to Grimm; Brockhaus says "6 Fuß; 10 Fuß; 1.7 m im Mittel"
* See also:
*
* Hercule Cavalli
* Tableaux comparatifs des mesures, poids et monnaies, modernes et anciens
* (Dupont, Paris, 1874)
*
* (available at Google Books) for such obsolete units.
*
* First observations published in letters from Krain = Carniola, on the
* bed of seasonally-varying Zirknitzer See = Cirknisko Jezero = Lago
* Periodico near Zirknitz = Cerknica = Cirkonico, south of Laibach =
* Ljubljana. This southern former crownland of Austria, later titular
* duchy, was annexed by the Hapsburgs in 1335. Note the use of Viennese
* measures. This area is currently Slovenia.
*
* Both field measurements and indoor experiments with air heated by an
* iron strip. He repudiates his earlier error (of thinking that the
* surface air was thickened) in the Nachschrift , and now states that the
* heated air is thinned, as shown by the rising air over a candle flame,
* etc. He also notes the wavy appearance of the heated air as it rises.
* Detailed explanations of double images and image elongation at the
* fold line, with good ray diagrams.
*
* Abbé Tobias Gruber, K.K.Kameral-Baudirektor
* note obsolete spelling: "Stralenbrechung"!
* The umlauts are tiny e's printed over the vowels.
* N.B.: Brechmonat = June; Wintermonat = Nov.|Jan.; Christmonat = Dec.
* Pernter gives 1786 for the year, and in the bottom margin at the end
* of every signature my photocopy says "Abh. d. B.Ges. 1786".
* The text (but, of course, NOT the Plates!) is available at Google Books.
* EARLY TREATMENT OF LOOMING & FATA MORGANA, with SUPERIOR MIRAGES
* more "FOG" (p.16)
* ". . . hier wähle ich zum Beyspiele meiner Beschreibung die bekannten
* Gunnilas Felsen, (Gunnilas Oerar) 3/4 schwedische Meilen ostwärts in der
* See von den Svenska Högar.
* "Vermutlich sind diese Gunnilas Felsen auf gewisse Art vor mehr als
* zwei Jahrhunderten bekannt gewesen. . . ."
* GUILLAUME JOSEPH HYACINTHE LE GENTIL's posthumous work on refraction
* Notable not only for an early OMEGA description, but also for the early
* use of the term se mirer and descriptions of mirages (pp. 233 ff.).
* A comment on the RARITY of clear sunsets: ". . . sur quatre mois
* entiers je n'ai vu qu'une seule fois le soleil se coucher complètement
* à l'horizon de la mer . . . ." (p. 227)
* He also notes that Bouguer found a smaller horizontal refraction at
* sea in the tropics (25' to 27') (p. 227)
* His own VARIATIONS in horizontal refraction were 5' at Pondicherry;
* but "il semble . . . que la réfraction à 10'' [sic; he means degrees]
* soit assez bien constatée . . . ." (p. 228)
* The OMEGA descriptions are on pp. 229-232. ". . . c'étoit comme si deux
* soleils se fussent détachés l'un de l'autre, l'un avoit monté pendant
* que l'autre descendoit." (p. 230)
* The etymology is on p. 233: "Les habitans des bords des côtes de
* Basse-Normandie, presque tous marins, appelent ces apparences se mirer .
* Ils disent qu'une isle se mire , qu'un rocher se mire ." He then
* disputes the French translation of a Dutch sailors' dictionary that
* invokes clouds in explaining this term, as "Cela n'arrive que dans un
* très-beau temps, et lorsqu'il n'y a pas la moindre apparence de nuages."
* (p. 234) -- Later on the same page is a classical description: "Je
* vis à la place comme des ruines d'une ancienne ville ou d'une ancienne
* colonnade, qui paroissoit au-dessus de l'horizon, et comme en l'air,
* sans distinguer ni voir de nuages quelconques."
* NOTE: The dictionary was Aubin's 1736 edition; see Aubin (1702) here.
* Finally, he quotes from Maraldi's descriptions of mirages and looming
* of Corsica as seen from Gênes and Provence. (p. 235)
* A footnote says Le Gentil died 22 Oct. 1792, just as the memoir was
* being printed.
* GIUSEPPE MARIA GIOVENE's original account -- very good!
* The mirage observations are on pp. 15-21: "It remains for me to speak
* of a phenomenon seen by me on the evening of 9 February, and of other
* similar phenomena, which are observed in these regions. For greater
* accuracy I shall copy almost literally from my journals for those which
* I have observed, and the reports of my friends, for those I have not
* seen with my eyes. The previous days were fine and clear, with rather
* strong winds from N. to W., and I found myself in a small country house
* which I prefer just because, enjoying a wide horizon there, I have the
* convenience of better observing the meteorological phenomena. It was
* one of those beautiful evenings that can happen in winter, and close
* to half past 5 in the evening I was stopped at a window that had a view
* directly to the SSW. I was enjoying the clear air, which was calm, as
* shown by the smoke from the chimneys of the nearby towns of Terlizzi,
* Ruvo, and Corato, which lay beneath my view; it had not any movement,
* but covered those towns motionlessly like an umbrella. Looking around,
* I thought I saw some clouds rising in the western part just along the
* horizon, which occupied about 20 degrees of the same. I determined to
* try to observe their path, with only the idea of being able to predict
* which way the wind would blow the next day, and consequently what could
* be the state of the air, which, as I found myself in the countryside,
* interested me. In fact, I observed that the supposed clouds rose more
* and more above the horizon until they had ascended about two degrees.
* But suddenly they began to take various shapes, so that finally I
* realized they were quite different from clouds. I therefore invited
* Dr. Andrea Tripaldi, a young man well versed in good physics, and who
* had had the courtesy to join me for some days in tranquil solitude,
* to observe with me. We placed ourselves to observe more attentively.
* The originally supposed clouds were always changing shape. They first
* gave us the impression of a city standing along the horizon. We saw the
* shapes of buildings, of towers, of campaniles. At that moment, we came
* to suspect that the landscape of Cerignola, reflected to be situated in
* the direction of the phenomenon, but thirty-four Italian miles distant
* from the place of observation, was presented to our eyes by a powerful
* refraction of light in the atmosphere. But we saw the scene gradually
* change, and two little hills appeared, one facing the other, and these
* later were raised up, and squared off into magnificent towers with great
* apertures like windows, which let the light of the twilight pass through.
* I would hardly be able to describe the diverse shapes and the varied forms
* that were presented to our eyes. But later on our surprise increased.
* The twilight was very bright, and I noticed that waves of more vivid
* light were rising from time to time from the edge of the horizon up to
* an altitude of six or seven degrees. I first believed it could be an
* illusion of my eyes, and informed Sig. Tripaldi, who affirmed that he too
* saw what I said I saw. To assure ourselves, we agreed to inform each
* other when one of us perceived these waves of light. We always found
* ourselves in agreement. We went to another window, which faced directly
* to the WNW, and the thing appeared the same. The waves of light extended
* as far as the twilight extended, and were more vivid where it was more
* vivid, and less vivid where it ended. Five or six waves would come, and
* then a pause for one or two minutes, then they would recommence again.
* Meanwhile, the most capricious shapes were appearing on the line of the
* horizon. The spectacle lasted, charming and pleasant, near half an hour.
* As the twilight grew darker, so the striking appearance decreased in
* beauty, and ended completely after three quarters of an hour. The calm
* lasted all night. In the morning of the following day, 10 February, some
* mists rose, and cloudlets, from the W. At 10 1/2 in the morning the wind
* came from the W rather strong, but near evening the air clouded up, and
* the wind shifted to the N.W. with strong force; on the following day (the
* 11th), the thermometer suddenly fell by many degrees, there was a shower
* of snow, which even froze in some places more exposed to the cold wind.
* "This phenomenon, although peculiar in its circumstances, is
* nevertheless not new in Puglia, as it is not even new in Iapigia, today
* called the Province of the Land of Otranto, and I shall expand a little
* on this article so much more willingly as this class of phenomena is
* either completely unmentioned by the writers, or reported confusedly,
* or even with changes engendered by the ignorance and superstition of the
* populace. The one who has mentioned them with the greatest vivacity and
* accuracy is the celebrated Antonio Ferrari, called Galateo after his
* birthplace, a writer of the last years of the fifteenth, and the first
* of the sixteenth Century. in his elegant little book, reprinted so many
* times, De Situ Iapygiæ :" -- and here he quotes from Ferrari's Latin
* account (1558) in extenso .
* "The reader will forgive the long quotation. But it is not only in
* the places named by the Galateo that the mutate are seen. I find
* from the reports, it is also seen at Galatone, Soleto, and many other
* towns and villages of the cape of Lecce, that is, Cape Japigio.
* The mutate (as is written to me from there) consist of seeing in a
* great plain, now a sea, now a woods, now a town. These apparitions are
* observed only at the rising and setting of the sun.
* "In Puglia Peucezia, similar phenomena are also seen, and are called
* lavandaja [washerwoman], for what reason, I cannot say. They have
* taken it as a sign of change of weather. In fact, when after the wind
* has blown for a long time from a point on the horizon, the atmosphere
* calms to give place to an opposite flow, then is precisely the time when
* the lavandaja shows itself most beautifully. So too the season in
* which it most frequently appears is the autumn, and the winter too,
* although it is not rare in summer, and not extremely rare in spring.
* Indeed in summer there takes place almost daily a sort of little
* lavandaja , after midday, while the time of the phenomenon is properly
* around sunrise and sunset.
* "The ordinary appearance of the lavandaja from Molfetta is on
* Mt. Gargano. This mountain, about 50 miles distant from that city,
* appears like a cloud of a fairly deep blue color resting upon the
* horizon from the W.N.W. to the N.N.W. Of course, I shall not say
* that this mountain is the barometer of the Puglian sailors, and that
* visible or invisible, high or low, covered either completely by clouds,
* or as if by an umbrella of clouds, lets them predict the wind and the
* state of the Puglian atmosphere; I shall speak only of the lavandaja .
* The first time I saw this meteor, knowing nothing of the thing,
* I confess to have been distressed by it in the first moments. I was
* seeing the whole mountain shake, and undulate, as if an extremely violent
* earthquake shook its foundations, and made it totter. So I was seeing
* one part of the mountain collapse, forming a great valley; and then
* this, little by little, rose to form a new peak superimposed on the
* mountain. Beside this peak rose a second, a third; and these, little
* by little, were squared off into high towers; then they too collapsed
* and became valleys again. In sum, I was seeing that mountain in the
* most terrible convulsions. Afterwards, accustomed to observing such
* phenomena, I have very many times seen with the greatest pleasure the
* varied scenes that the view of this mountain offers. It assumes the
* most varied and the most capricious forms, and a warped or slightly
* heated imagination, comparing these figures to well-known objects,
* believes it sees horses, and armies, castles, ships, towers, and towns.
* "And too, a partial lavandaja is seen from the Town of Molfetta,
* especially when a soft wind blows from the east after sunset. That
* peak, of which Lucan sang,
*
* Apulian Garganus extends into the Adriatic waves
*
* continually takes on new forms and figures, now seeming extremely
* long, now shrinking and then dividing into many pieces, which look like
* islands in the open sea. It also happens that sometimes one portion of
* the sea appears notably higher than another, and some other time the sea
* in the distance looks as if in the greatest storm, when in reality it
* was completely calm. But to finish the little story of these phenomena,
* I shall describe another charming display that presented itself to me
* one morning in October, 1789, at the appearance of the sun on the horizon.
* "I found myself in my customary countryside retreat, and as it was
* a beautiful morning with little, or indeed no wind, I hastened to enjoy
* it at a window that looked directly to the N.E., and to observe the
* thermometer and the hygrometer, which hung there. I was really
* surprised to see the most delightful and certainly moving scene.
* The town of Biseglie, which was in my view, in the N.W. part, although
* it was seven miles away, appeared so near that I would have believed
* it only two miles off. I was seeing the pavement of a wide square,
* which is there before the walls of the town, was almost counting the
* houses, and the vision was made not only with the greatest distinctness,
* but also with a certain vividness, which absolutely touched the soul.
* It was observable that the houses seemed more elongated than widened,
* as it was most observable that the bell towers were in their natural
* state. That is to say that at a certain height of the land, the view
* was the normal one. In the part to the W., all the little hovels and
* the houses scattered through the countryside appeared as high pyramids
* or spacious towers. I enjoyed this display, which later became more
* delightful, for almost an hour, in the company of my inseparable friend,
* the aforesaid Dr. Andrea Tripaldi. The town of Trani, placed a little
* more to the W. at a distance of perhaps more than eleven miles, and
* which, in the ordinary state of the air, cannot be seen, except for
* just one cathedral with its high campanile, began to be seen entirely,
* and with the greatest distinctness, so that it seemed to have approached
* by at least six miles. At the start of the next hour, while Biseglie
* was slowly going away, Barletta began to be seen. It is even more to
* the west than Trani, and about eighteen miles distant, and completely
* invisible in the ordinary state of the atmosphere. And this town seemed
* no more remote than seven or eight miles. My colleague and I distinctly
* saw the coast between Barletta and Trani, and were counting all the little
* boats that were fishing along there. Near nine in the morning, that is,
* after more than three hours since we had begun to observe the phenomenon,
* everything seemed to return to normal. But I wanted to go onto the
* terrace, which was higher than the window by about twenty Paris feet.
* I was more surprised to find that from that height the phenomenon
* could still be seen in all its beauty, and Barletta and Trani seemed a
* few miles away. I informed Sig. Tripaldi of it as he stood at the window
* while I was on the terrace. We assured ourselves that the phenomenon was
* now invisible at the height of about 40 Paris feet, extremely visible from
* about 60 feet from the ground. In the whole duration of the phenomenon
* the thermometer was between 12 and 15 degrees Reaumur, and the hygrometer
* between 21 and 25 degrees absolute, which means in temperate heat,
* and moderate dryness; or at least, certainly not in great humidity.
* "By comparing my observations with the little left written of it by
* Antonio Galateo , it is easy to see that the mutate of Japigia and
* the lavandaja of Peucezia are the very same thing, although I will admit
* that the fuochi fatui [will-o'-the wisps] and the capre saltanti ,
* which are not seen by us at all in Peucezia, are extremely frequent
* in Nardò, and in Copertino. The complex of these meteors, and of
* the phenomena described above, gives credence to the tales of witches
* and magicians among the people of Nardò and Copertino; fables that
* nevertheless have begun to lose credit today even among those low people.
* "Meanwhile, everyone sees that the mutate and the lavandaja
* are nothing but the play of variable refraction of visual rays in the
* atmosphere, as from variable refraction comes the increase and decrease of
* our visual horizon by twenty or thirty miles. But a conversation on the
* phenomenon I had seen on the evening of 9 February with the celebrated
* Sig. Thouvenel (whose coming to Molfetta expressly to visit the famous
* natural nitrate deposit of this City gave me the honor of accomodating
* him in my house, and the pleasure of hearing him, . . . ) made my ideas
* go a little farther, and formed conjectures, which will be appraised
* by the Physicists for what they are. Why does this lavandaja always
* have to appear on the western side and never to the east of Molfetta?
* Why must it always be seen along the line going from the famous Apulian
* [Mt.] Vulture, an extinct volcano, as everyone knows, and entering the sea
* at the farthest promontory Gargano, passing by the island of Pelagosa,
* recognized as volcanic by the celebrated Sig. Ab. Fortis, and going
* directly to the N.E. to join the volcanos of Morlachia? Why are the
* mutate of Lecce seen along the line of Galatona, Nardò, Copertino,
* and adjacent towns, put on land where there is some rising heat, and
* where pyrites and coal are found? Why is the famous fata morgana of
* Reggio in Calabria, which nevertheless is very similar to the lavandaja
* of Puglia, and to the mutate of Salento, is found just on the line
* of coal, which passed directly under the Faro of Sicily in Calabria,
* and is also seen in the open air behind Messina, and at Briatico on the
* opposite side? This phenomenon of the lavandaja , that is, of the
* mutate , is certainly, as I have said, a play of refraction, and to
* make such a play it is necessary that a certain quantity of vapors and of
* exhalations change the state of the atmosphere. Even this is not enough.
* Because the striking appearance, despite the calm, means that the wind is
* in continuous movement, the very air is like an uprising, and agitated.
* Those waves of light that I saw the evening of 9 February must be the
* effect of a shaking given to the air. So it seems that either electrical
* fluid or other emanations of some gas rise from the regions above which
* are seen the described phenomena, and force the incumbent atmosphere to
* be disturbed or to undulate. The violent agitations and convulsions,
* to which the same atmosphere is accustomed, occur after the appearance of
* such meteors, which indicate the same. I have not thought it necessary
* to give a complete history of this kind of phenomenon in our regions in
* this memoir. For me, it is enough to have given a small sample of it.
* Meanwhile, one must confess that meteorology is still, at most, in its
* early adolescence, and that there would never be as many careful observers
* of meteorological instruments as observers in the open countryside,
* and with a free horizon."
*
* This was mostly translated into German by Zimmermann later, and then
* reprinted by Gilbert in 1802. (See the entry for Zimmermann's version.)
* Thanks to Maria Toscano for supplying the citation to this, and
* helping with the translation!
* Available at Google Books:
* https://books.google.com/books?id=BN0WAAAAYAAJ&pg=PA3&f=false#v=onepage&q&f=false
* Early looming and mirage observation (apparently a 3-image mirage)
* "On the thirteenth of last month [i.e., October], while we lay on
* the banks of Lake-Erie, we had an opportunity of viewing that singular
* phenomenon, by Seamen termed looming. . . . the 13th was cloudy; but
* without rain: about ten o'clock in the morning, as I was walking on the
* beach, I discovered something that had the appearance of land, in the
* direction of Presque-Isle; about noon it became more conspicuous and;
* when viewest by a good Achromatic-Telescope, the branches of trees
* could be plainly discovered --- From 3 o'clock in the afternoon, till
* dark, the whole Peninsula was considerably elevated above the horizon,
* and viewed by all our company with admiration. --- There was a singular
* appearance attending this Phenomenon, which I do not remember to have
* seen taken notice of by any writer --- The Peninsula was frequently
* seen double, or rather two similar Peninsula's, one above the other,
* with an appearance of water between:--- the separation, and coincidence
* was very frequent, and not unlike that observed in shifting the index
* of an adjusted Godfrey's quadrant. . . . The next morning Presque-Isle
* was again invisible, and remained so during our stay at that position.
* Presque-Isle was about twenty-five miles distant, its situation very low."
* The marginal note says "Read Nov. 21, 1788".
* EARLY DRAWING of SUPERIOR MIRAGE (FATA MORGANA + SUPERIOR MIRAGE)
* by the Rev. Samuel Dickenson, LL.B. the Chaplain of the Dunkirk
* Man of War. . .
* "The term haze , prefixed to the foregoing account, is adopted from the
* phrase then used by the sailors, perhaps improperly; for, there was not
* the least appearance of mist or fog, or thickness of atmosphere; on the
* contrary, the air seemed uncommonly clear."
* INFERIOR MIRAGE and variable refraction reported by
* Lieut. Col. Edward Williams, and Capt. William Mudge,
* of the Royal Artillery; and Mr. Isaac Dalby.
* Dalby's observation in April, 1793 (pp. 586-588):
* "I observed . . . a very uncommon effect of terrestrial refraction. . . .
* ". . . when the eye was brought to about 2 feet from the ground, the top
* of the hill appeared totally detached, or lifted up from the lower part,
* for the sky was seen under it. This phænomenon I repeatedly observed."
* The discussion continues: ". . . it is more than probable, that moist
* vapours were the principal cause of the very unusual refractions:
* the truth of which conjecture seems to be verified by the following
* circumstance. In measuring the base on Hounslow Heath, we had driven
* into the ground, at the distance of 100 feet from each other, about 30
* pickets, so that their heads appeared through the boning telescope to be
* in a right line; this was done in the afternoon. The following morning
* proved uncommonly dewy, and the Sun shone bright; when having occasion to
* replace the telescope, we remarked that the heads of the pickets exhibited
* a curve, concave upwards, the farther-most pickets rising the highest;
* and we concluded they were not properly driven till in the afternoon,
* when we found that the curve appearance was lost, and the ebullition in
* the air had subsided."
* (available at JSTOR; no paper copy filed)
* Woltman's newsletter announcement (1796)
* This is the lead item in the issue, attributed to "Hr. Dir. Woltmann"
* (with 2 "n"s.) "zu Cuxhaven". There is no title; the general heading
* is "Göttingen". This is an account of a paper sent to "der königl.
* Societät" [i.e., the "Königliche Gesellschaft der Wissenschaften" in
* Göttingen], and presented by "Hr. Hofrath Kästner". (The Göttingische
* Gelehrte Anzeigen was its official organ, published almost daily.)
* This extended abstract begins with Gruber's 1786 paper, and goes
* directly into an account of Woltman's measurements of dip by using two
* stakes driven into the dikes, with the distant house as target. This
* seems to be the first appearance of the phrase "Spiegelung unterwärts" in
* print. The basic data (distances between the sights and the house, and
* some angles) are given, with the Hamburg foot as the unit of length.
* The part of his later complete table that summarizes the results for
* Feb. 1795 is printed, showing that the terrestrial refraction is
* greatest in the morning and least in the evening; the total range is
* 10 min. 16 sec.
* "Diese Bilder können nicht ganz allein aus Reflection entstehen, weil
* keine Spiegelfläche in der Luft vorhanden ist; es muss dabey eine
* Refraction mitwirken, die den Strahl unterwärts krümmt." (p. 812)
* He also describes briefly the effects of superior mirages, and for
* further information refers to his forthcoming paper in the "nächsten
* Bande der kaiserl. königl. Gesellschaft zu Prag". The heat has the
* strongest effect of all meteorological variables: "Ist das Wasser 2 oder
* mehr Fahrenheitische Grade wärmer, als die Luft, so findet sich allemal
* Erniedrigung der Strahlen, die sich über die Wasserfläche erstrecken;
* aber Hebung, wenn die Luft über dem Wasser 2 oder mehr Grade wärmer ist,
* als das Wasser." (p. 815)
* At the end, Woltman describes some inferior mirages he has seen over
* land: "Man muss zu dem Ende eine ganz offene Ebene vor sich haben ,
* oder über Gebüsche und dergl. von einer hohe wegsehen können. Dann
* scheint die ganze Landschaft in einem unbeweglichen Glanzmeere zu stehen ,
* worin alle die erhobenen Gegenstände sich unterwärts spiegeln. So hat
* Hr. W. oft von den Geesthöhen herab die Marschen gesehen , als wären
* sie ganz mit glänzendem Wasser überzogen. Diese Bemerkungen . . . findet
* er Uebereinstimmung der Strahlen über Land und über Wasser, der Strahl
* krümmt sich allemahl nach der wärmsten Seite; die Refraction ist desto
* grösser, je grösser der Unterschied der Wärme zwischen beyden Materien
* ist, . . . ." (p. 817)
* He continues with remarks on distortions of the low Sun: "Sieht man
* die Sonne des Morgens heiter aufgehen , so gibt ihre Gestalt ein
* untrügliches Merkmahl , ob Hebung oder Depression Statt finden wird.
* Nähmlich im letztern Falle ist sie nie rund , sondern ein Theil
* der Sonnenscheibe spiegelt sich unterwärts ; der kann , nachdem die
* Depression schwacher oder stärker ist, wohl ein Achtel oder ein Viertel
* des Sonnendurchmessers betragen, Hr. W. bildet dergleichen
* Erscheinungen ab , als wenn unten an der Sonnenscheibe , auch an den
* aufgegangenen Theil, der Anfang einer andern Scheibe angesetzt wäre ;
* dergleichen hat er auch an dem Vollmonde wahrgenommen. Findet dergleichen
* Depression Morgens und Abends Statt, so ist ihre Dauer auf dem festen
* Lande denselben Tag keinem Zweifel unterworfen , weil sie hier um Mittag
* allemahl zunimmt." (p.818)
* Evidently the editor --- at that time, Christian Gottlob Heyne, the
* head of the University Library, and "perpetual secretary" of the Society
* --- thought highly of this report: "Das viele Merkwürdige und Neue
* aus einer noch ungedruckten Schrift wird die Länge dieses Auszugs
* entschuldigen."
* This journal did not have conventional volume numbers; the Bände were
* given year numbers, starting in 1753. The title page of this volume says
* "Der erste Band, auf das Jahr 1796." There were two volumes in 1796;
* this is the first one. The "piece" number is 82, dated 21. Mai. This
* first volume for 1796 ends on page 1040 of the 104th Stück, dated 10 Jun.
* The second volume of 1796 follows on p.1041 of the 105th St.; at its end
* (at page 2105) come the alphabetical indices (separately paginated) and
* a list of printer's errors.
* This is the 82. St. of 1796.
*
* Available at
* https://www.google.com/books/edition/G%C3%B6ttingische_Anzeigen_von_gelehrten_Sac/ujtKAAAAcAAJ?hl=en&gbpv=1&bsq=809
* or
* https://gdz.sub.uni-goettingen.de/id/PPN31973076X
*
* Eberhard August Wilhelm von Zimmermann's translation of Giovene
* The introduction refers to Swinburne's work, and briefly enumerates
* the various sources, and their translators.
* Giovene's interesting mirage passage is on pp. 171-181. Zimmermann
* does indeed copy "S.S.O." literally from the original, which garbles
* the directions, as "O." is "Ovest" in Italian. So the error is the
* translator's and not Gilbert's.
* Note: the umlauts are tiny e's above their vowels.
* Available at
* https://digitale.bibliothek.uni-halle.de/vd18/content/titleinfo/8125331
* EARLY OBSERVATION & EXPLANATION OF INFERIOR MIRAGES and DIP
* "The variation and uncertainty the dip, in different states of the
* air, taken at the same altitude above the level of the sea,, was the
* occasion of my turning my thoughts to this subject; as it renders the
* latitude observed incorrect, by giving an erroneous zenith distance of
* a celestial object.
* "I have often observed that low lands and the extremity of headlands
* or points, forming an acute angle with the horizon of the sea, and
* viewed from a distance beyond it, appear elevated above it, with an
* open space between the land and the sea. . . . I believe it arises,
* and is proportional to the evaporation going on from the sea; and in
* reflecting upon this phænomenon, I am convinced that those appearances
* must arise from refraction, and that instead of the density of the
* atmosphere increasing to the surface of the sea, it must decrease from
* some space above it; . . . ."
* His observations of the miraged ship, made from a height of 40 feet,
* [=12 m] plainly showed the contraction of the inverted image. (p.32)
* His figures show accurate ray diagrams for the inferior mirage;
* he notes the vanishing line ("a little below the maximum of density,
* where inversion begins; therefore no land lower than this can be seen;
* . . . " (p. 37); and he points out the effects seen at the fold line:
* "There are always confused or ill defined images of the objects at
* the height of the dotted line, fig. 1, above the level of the sea, as
* before mentioned; and instead of the points of d [i.e., the apparent
* land horizon] ending sharp in that line, they appear blunted . . . ."
* Notable for having used measurements of the Sun at noon at both
* northern and southern (i.e., opposite) horizons to infer the actual DIP.
* He says "The effect indicated by the barometer and thermometer is
* insufficient;" but he fails to understand why, being fixed on the idea
* that humidity is the main problem.
* Cites Hamilton (1766) on "Ascent of Vapours". Also cites the paper by
* Williams, Mudge, and Dalby (1795).
* Joseph Huddart read his paper to the Royal Society on November 24.
* 1796. It was published on Jan. 1, 1797.
* Available at JSTOR, and at the Roy. Soc. website.
* The same, reprinted:
* Note: Nicholson's Journal merged with Phil. Mag. in 1813.
* Nicholson's summary of MINASI's Fata Morgana paper
* He begins by quoting James Thomson's lines from "The Castle of Indolence",
* Canto i. Stanza 30: "As when a shepherd of the Hebrid' Isles. . .
* (Whether it be lone fancy him beguiles,
* Or that ae"rial beings sometimes deign
* To stand, embodied, to our sense plain) . . .
* A vast assembly moving to and fro:
* Then all at once in air dissolves the wondrous show."
* -- an interesting reference, considering the reports of mirages from
* the Orkneys and other northern outliers of Britain.
* He then cites Brydone and Swinburne as making "mention of a very
* striking phenomenon . . . known by the name of Fata Morgana, or, as some
* render it, the Castles of the Fairy Morgana. The accounts differ from
* each other . . . . How far the effects themselves may be subject to
* variation, or to what extent the imagination of the narrators, who speak
* of the exhibition as calculated to produce astonishment, may be subject
* to irregularity, would admit of discussion. . . ."
* Nicholson borrowed a copy of Minasi's work from Sir Joseph Banks,
* and says, "In this treatise the facts are related with much simplicity
* and precision, and the philosophical reasoning of the author is kept
* distinct from the narrative." [But see Gilbert's scathing commentary!]
* Now comes Nicholson's loose translation of Minasi's description:
* "When the rising sun shines from that point whence its incident
* ray forms an angle of about forty-five degrees on the sea of Reggio,
* and the bright surface of the water in the bay is not disturbed either
* by the wind or the current, the spectator being placed on an eminence
* of the city, with his back to the sun and his face to the sea; -- on
* a sudden there appear in the water, as in a catoptric theatre, various
* multiplied objects, that is to say, numberless series of pilasters,
* arches, castles well delineated, regular columns, lofty towers, superb
* palaces, with balconies and windows, extended alleys of trees, delightful
* plains with herds and flocks, armies of men on foot and horseback, and
* many other strange images, in their natural colours and proper actions,
* passing rapidly in succession along the surface of the sea during the
* whole of the short period of time while the above-mentioned causes remain.
* "But if, in addition to the circumstances before described, the
* atmosphere be highly impregnated with vapour, and dense exhalations not
* previously dispersed by the action of the wind or waves, or rarefied by
* the sun, it then happens that in this vapour, as in a curtain extended
* along the channel to a height of about thirty palms, and nearly down
* to the sea, the observer will behold the scene of the same objects not
* only reflected from the surface of the sea, but likewise in the air,
* though not so distinct or well defined as the former objects from the sea.
* "Lastly, if the air be slightly hazey and opake, and at the same time
* dewy and adapted to form the iris, then the above-mentioned objects
* will appear only at the surface of the sea, as in the first case,
* but all vividly coloured or fringed with red, green, blue, and other
* prismatic colours." [Minasi actually says "purple" rather than "other
* prismatic colors."]
* Nicholson's translation seems to have become the canonical version
* of Minasi's account in English (though in Brewster's 1830 "Edinburgh
* Encyclopedia" and some later copies, "alleys" became "valleys").
* (Google Books shows dozens of copies, right up to the present day.)
* Minasi just says "very high trees" -- no alleys or valleys.
* Nicholson refers to Minasi's note on "the etymology of Morgana
* . . . which is so foreign to the Roman idiom, . . . considering the great
* exultation and joy this appearance produces in all ranks of people, who
* on its first commencement run hastily to the sea, exclaiming Morgana,
* Morgana!"
* "In the second chapter the author describes the city of Reggio,
* and the neighbouring coast of Calabria; by which he shews that all the
* objects which are exhibited in the Fata Morgana are derived from objects
* on shore." (I take "derived from" in a different sense, though!)
* In dealing with Minasi's observation (in the 3rd chapter) that the
* tides have something to do with it, he takes from Minasi that "It is high
* water, that is to say, the northern current ceases, at full and change,
* at nine o'clock. There is probably a small rise and fall, though the
* annotation to a large chart before me affirms that there is none."
* The various crank ideas following the 4th chapter, in which Minasi
* "collects the opinion and relations of various writers . . . , namely,
* Angelucci, Kircher, Scotus, and others," are elided, "because it seems
* difficult to make any clear or productive statement either from the
* narrative or the reasoning." [Pace , Gilbert!]
* His summary includes: "3. That the Morgana Marina presents inverted
* images below the real objects, which are multiplied laterally as well
* as vertically; and that there are repetitions of the same multiplied
* objects at more considerable vertical intervals. This I gather from
* the appearance of the dome and other objects in the plate." And:
* "8. By attentive reflection upon the facts and reasonings in Mr.
* Huddart's paper, we may form a theory to account for the erect and
* inverted images . . . ; but for the lateral multiplication we must have
* recourse to reflecting or refracting planes in the vapour, which appear
* nearly as difficult to deduce or establish, as those which have been
* supposed on the water."
* Issue dated August 1797
* William LATHAM's observations of LOOMING, seen from Hastings
* "On Wednesday last, July 26, about five o'clock in the afternoon, . . .
* the coast of France was plainly to be distinguished with the naked eye.
* I immediately went down to the shore, and was surprised to find that,
* even without the assistance of a telescope, I could very plainly see the
* cliffs on the opposite coast; which, at the nearest part, are between
* forty and fifty miles distant, and are not to be discerned, from that
* low situation, by the aid of the best glasses. They appeared to be only
* a few miles off, and seemed to extend for some leagues along the coast.
* . . . the cliffs gradually appearing more elevated, and approaching
* nearer, as it were . . . .
* "Having indulged my curiosity upon the shore for near an hour, during
* which the cliffs appeared to be at some times more bright and near,
* at others more faint and at a greater distance, but never out of sight,
* I went upon the eastern cliff or hill, which is of a very considerable
* height, when a most beautiful scene presented itself to my view; for
* I could at once see Dengeness, Dover cliffs, and the French coast,
* all along from Calais, Boulogne, &c. to St. Vallery; and, as some of
* the fishermen affirmed, as far to the westward even as Dieppe. . . . This
* curious phenomenon continued in the highest splendour till past eight
* o'clock, (although a black cloud totally obscured the face of the sun
* for some time,) when it gradually vanished.
* "I should observe, the day was extremely hot, as you will perceive
* by the subjoined rough journal of a small thermometer, . . . and the three
* preceding days were remarkably fine and clear. . . . Not a breath of wind
* was stirring the whole of the day . . . .
* Latham's temperature log shows that at 10 A.M. each of the previous
* 3 days, the temperatures were 65, 66, and 66 (F), and 68 on the day of
* looming; but at 5 P.M. it was 76. The 10 A.M. temperatures on the next
* 4 days were 72, 70, 72, and 70; so it appears the looming accompanied
* the arrival of a warm front.
* Reprinted in Nicholson's Journal 2, 417-419 (1799).
* Cf. the similar observations of Parnell (1869).
* REINHARD WOLTMAN's 1798 paper
* This is the paper partly reprinted by Gilbert in Ann. Phys. 3, 397 (1800)
*
* At this time, Woltman was "Baudirektor im hamburgischen Amte Ritzebüttel"
* A footnote on the first page says that Woltman began this work toward the
* end of the year 1794, continued it in 1795, and finished on 8. Nov., and
* communicated it in part with Abbe Gruber. It was extensively reviewed in
* the "Götting. Anzeigen 82ten Stück, 21ten May 1796."
* There is some background information on Woltman in the prefatory pages.
* On p. III we see that he was not a member of the Bohemian Scientific
* Society, but had submitted his manuscript to it through Abbe Gruber.
* On p. XXIII we learn that he was "Direktor der Ufer und Wasserbauwerke im
* hamburgischen Amte Rützebütl", and a member of several scientific
* societies, some in Harlem and Rotterdam; but here he is in a list of
* foreign members.
* He begins with a classic description of inferior mirages:
* "The phenomenon is that objects, houses, trees etc. near the horizon
* often are separated from the visible ground surface by a bright strip of
* air, and almost seem to stand in the air; or as if a shining empty space
* were present between the visible horizon and the objects; or if the eye is
* considerably raised, and sees several distant objects behind one another,
* as if these houses, mills, churches, trees etc. stood in a calm shining
* sea, in which the entire landscape were immersed and reflected."
* This is followed by an extensive list of "Alle, die davon geschrieben
* haben: Gruber's 1781 "Briefe"; Büsch's 1783 "Tractatus duo"; Gruber's
* 1786 response. "Diese zwey Abhandlungen hat H. Hofrath Kästner in seiner
* Dioptrik 1792 nebst mehreren Beyspielen angeführt; unter andern, dass H.-
* Justizrath Niebuhr einen Araber auf einem Kamele in freyer Luft reiten
* gesehen. Siehe dessen Reisebeschreibung nach Arabien 1. Theil, S. 253."
* "Ich habe selbst mit einem achromatischen Fernrohr sehr deutlich
* wahrgenommen, dass die entfernten Häuser, Bäume, Schiffe in umgekehrter
* Gestalt sich sehr deutlich abbilden, wie eben dieselben Gegenstande
* in de Nähe thun, wenn zwischen ihnen und dem Auge ein ganz ebener
* Wasserspiegel befindlich ist."
* VISIBILITY IN RAIN:
* "Auch sieht man das Phänomen so gut gleich nach einem Regen, als vor
* demselben; und selbst im Regen verschwindet es nicht eher, als bis die
* Undurchsichtigkeit der Luft das Sehen in der Ferne verhindert." (p. 71)
* He then describes the qualitative effects of object distance and eye-
* height. "Woraus folgt, dass nur diejenigen Strahlen von den Objecten
* durch Reflexion ins Auge kommen, die unter sehr kleinen Winkeln auf
* die spiegelnde Fläche fallen." And he describes how the "bright strip"
* shrinks and vanishes as the miraged object approaches the observer;
* and similarly describes the effects of increasing the height of the eye.
* "Therefore the bright strip is no object, like a luminous surface, . . .
* but is itself an image of a reflected bright object." (p. 72)
* On the next page, he tries to explain the phenomena with ray diagrams;
* he knows that the curvature of the Earth is important, but he draws all
* the rays as straight lines, except where they are reflected. Still, this
* allows him to explain why the apparent horizon is lowered by the mirage.
* He also explains that all the miraged objects lie beyond the effective
* distance to the horizon. (p. 74)
* In §.10. (p.75) he points out that "the images are always considerably
* smaller than their objects." He has found the images generally about
* half the size of the object, and shows an example in Fig. 7. Unfortunately,
* he neglects the curvature of the Earth; so he thinks this might be due to
* the rays being reflected under a smaller angle than that of incidence!
* But "maybe the refraction has something to do with it." On the next page,
* we find the real cause: his eye (in his house at Cuxhaven) is 3 toises
* (almost 6 meters) above the high-water level.
* He goes through a very rough argument that neglects the curvatures of
* both the surface and the rays, and then weasels out: "Zu genauern
* Bestimmungen wären genauere Beobachtungen mit einem Mikrometer nöthig;
* auch musste wohl die Refraktion in Betracht gezogen werden; welches zu
* unternehmen ich mir nicht getraue." (p.77)
* In §.13. he begins by discussing the trembling motion of the images,
* and compares it with the appearance of objects seen through the "vapors"
* above a coal fire. But then in the middle of the paragraph he gets into
* a description of superior mirages: "Eben diese Dünste im aufgelösten,
* durchsichtigen Zustande vergrössern zuweilen die horizontale Refraktion
* dermassen, dass die Meeresfläche, entlegene Ufer, Küsten und Sandbänke
* eine ganz ungewöhnliche Gestalt annehmen. Die Meeresfläche wird concav
* gekrümmt, die nähern Schiffe erniedrigen sich, oder vielmehr der entlegne
* Horizont scheint über ihnen fast hervor, entfernte niedrige Ufer erscheinen
* wie hohe Küsten; und diese, wenn sie auch 7 oder 8 Meilen entfernt, und
* weit unterm Horizont sind, erscheinen wie Gewölke über demselben; ganze
* Landschaften, die man sonst wegen der vorliegenden Sandhügel nicht sehen
* kann, erscheinen über dieselben hervor." (p. 78)
* Next, he worries about how to explain the "reflection". "Die Erdfläche
* selbst, so wie auch das Wasser, wenn es vom Winde in Unruhe gesetzt wird,
* sind zu rauh, um Bilder zu machen."
* "Mein würdiger Lehrer, der Hr. Prof. Büsch pflegte in der Optik zu
* bemerken, dass die zurückwerfung nicht unmittelbar an den Flächen,
* sondern in einer kleinere Entfernung von denselben . . . geschehe."
* He then describes a case where the mirage was seen at both high and
* low tide, when the water was 1½ toise lower; "Die Erniedrigung der
* Meeresfläche hat also denselben Effekt, den eine wirkliche Erhöhung
* des Auges oder des Objects haben würde . . . ."
* In the second part (p. 81) he considers whether the reflecting surface
* shares the curvature of the Earth, and whether this can explain the
* reduced size of the images. Unfortunately, because he neglects some
* small quantities, he thinks the reflection at a spherical surface will
* be the same size as the object, just as if the surface were flat.
* On p. 86, he says that mirages were sometimes still visible in late
* January, when the ground and the ice on the river were covered with snow.
* DIP and the inferior MIRAGE:
* His quantitative measurements of terrestrial refraction (given in
* the Table facing p. 86) clearly show a correlation between refraction and
* the inferior mirage: "bey verstärkter Refraktion oder Hebung des Hauses
* niemals Spiegelung gewesen; oder umgekehrt, dass bey der Spiegelung das
* Haus allezeit weniger erhaben gewesen, folglich eine relative Depression
* der Objekte wenigsten bey der Spiegelung statt habe."
* These measurements clearly establish the connection between refraction
* and the air-water temperature difference, and likewise the connections
* between the inferior mirage and depression, and the superior mirage and
* looming. Here is his memorable "2 deg. Fahr." rule; "unter mehr als 150
* Beobachtungen hat diese Regel keine Ausnahme." (p. 95)
* Woltman's final remark is that these phenomena are very well described
* by Martinet in the Verhandelingen der holländ. Gesellsch. zu Harlem XXVII.
* Deel. II. Stück, under the title "Warneemingen omtrent het opdoemen van
* Zee en Land".
*
* Woltman's figures are at the very end of the volume; in Google's scan at
*
* https://www.google.com/books/edition/Neuere_Abhandlungen_der_k%C3%B6niglichen_B%C3%B6/nqpeAAAAcAAJ?hl=en&gbpv=1&dq=Woltman+Bemerkungen+1798+katoptrisches&pg=PA69&printsec=frontcover
*
* they come after Gruber's figures, at image 491.
*
* Notice the correct spelling of his name here.
* Gruber's comments on Woltman's immediately preceding paper
* [partly reprinted by Gilbert in Ann. Phys. 3, 439 (1800).]
* Gruber's ray diagrams are all drawn for a flat Earth, so he has to
* violate symmetry in them in trying to explain the compression of the
* inverted image in the inferior mirage.
* The Tafel showing Gruber's figures is image 475 in the Google Book.
* early report of SUPERIOR MIRAGE, by Jean François Galaup de La Pérouse:
* (filed slightly out of order to stay with the English translations)
* The mirage observation itself is on p. 10 of Tome 3:
* "Les journées du 15 et du 16 furent très brumeuses ; nous nous
* éloignâmes peu de la côte de Tartarie, et nous en avions connaissance
* dans les éclaircis ; mais ce dernier jour sera marqué dans notre
* journal par l'illusion la plus complète dont j'aie été témoin depuis
* que je navigue.
* "Le plus beau ciel succéda, à quatre heures du soir, à la brume la
* plus épaisse ; nous découvrîmes le continent, qui s'étendait de l'Ouest
* un quart Sud-Ouest au Nord un quart Nord-Est, et peu après, dans le
* sud, une grande terre qui allait rejoindre la Tartarie vers l'Ouest,
* ne laissant pas entr'elle et le continent une ouverture de 15d. Nous
* distinguions les montagnes, les ravins, enfin tous les détails du
* terrain ; et nous ne pouvions pas concevoir par où nous étions entrés
* dans ce détroit, qui ne pouvait être que celui de Tessoy, à la recherche
* duquel nous avions renoncé. Dan s cette situation, je crus devoir serrer
* le vent, et gouverner au Sud-Sud-Est ; mais bientôt ces mornes, ces ravins
* disparurent. Le banc de brume le plus extraordinaire que j'eusse jamais vu
* avait occasionné notre erreur : nous le vîmes se dissiper ; ses formes,
* ses teintes s'élevèrent, se perdirent dans la région des nuages, et nous
* eûmes encore assez de jour pour qu'il ne nous restât aucune incertitude
* sur l'inexistence de cette terre fantastique. Je fis route toute la nuit
* sur l'espace de mer qu'elle avait paru occuper, et au jour rien ne se
* montra à nos yeux ; l'horizon était cependant si étendu que nous voyions
* parfaitement la côte de Tartarie, éloignée de plus de quinze lieues."
* This observation was made the 16th of June, 1787 -- just in the middle
* of superior-mirage season, for mid-latitudes (they were about 44° N).
* The location was off the coast of the Sikhote-Alin mountain range, ENE
* of present-day Vladivostok. The introductory remark indicates that
* La Pérouse was familiar with mirages.
* Furthermore, they had directly observed a strong thermal inversion a
* few weeks earlier (May 26), a little farther south in the Sea of Japan:
* "Si les nuages ne nous avaient par annoncé ce changement, nous avions
* eu néanmoins un avertissement que nous n'entemdîmes pas, et qu'il n'est
* peut-être pas facile d'expliquer : les vigies crièrent du haut des mâts
* qu'elles sentaient des vapeurs brûlantes, semblables à celles de la
* bouche d'un four, qui passaient comme des bouffées et se succédaient
* d'une demi-minute à l'autre. Tous les officiers montèrent au haut
* des mâts et éprouvèrent la même chaleur. La température était alors
* de 14d sur le pont ; nous envoyâmes sur les barres des perroquets un
* thermomètre, et il monta à 20d : cependant les bouffées de chaleur
* passaient très-rapidement, et, dans les intervalles, la température de
* l'air de différait pas de celle du niveau de la mer." (T.2, p.389-390)
*
* Title page reads:
*
* V O Y A G E
* D E L A P É R O U S E
* AUTOUR DU MONDE,
* publié
* conformément au décret du 22 avril 1791,
* ET RÉDIGÉ
* par M. L. A. MILET-MUREAU
*
* Thanks to Luc Dettwiller for discovering the mirage report!
* 1st English translation of La Pérouse:
* This edition uses the long-s, and seems to have been the "popular"
* rather than the "official" translation. The mirage story reads:
* "The 15th and 16th of June were very foggy days. We kept within a
* small distance of the coast of Tartary, and got sight of it at intervals;
* but the last of these days will be distinguished in our journal by the
* most complete illusion I have witnessed since I have been a seaman.
* "At four in the afternoon a perfectly clear sky succeeding to the
* thickest fog. we descried the continent extending from W. by S. to N. by
* E. and soon after, an extensive land in the south, running towards Tartary
* in the west, where it left an opening of less than fifteen degrees.
* We distinguished the mountains, hollows, and all the variations of the
* ground, but could not imagine how we had entered this strait, which must
* necessarily be that of Tessoy, of which we had given up the pursuit.
* In this situation I thought it necessary to haul the wind, and steer
* S. S. W.; but these hills and hollows soon disappeared. The most
* extraordinary fog-bank I had ever beheld occasioned this deception,
* and we soon witnessed its dispersion. Its forms and its tints mounted,
* and vanished in the atmosphere among the clouds; and enough of day still
* remained fully to demonstrate that land to be unsubstantial and imaginary.
* I stood on, during the night, over the space it had appeared to occupy,
* and at day-break no object presented itself to our view. The horizon was
* even sufficiently extensive to admit of our distinctly seeing the coast of
* Tartary, although more than fifteen leagues distant. I shaped my course
* towards it, but at eight in the morning the fog again surrounded us."
* [The above passage appears on pp. 27-28 of Vol. II.]
* 2nd English translation of La Pérouse:
* This edition uses the short s, and is written in a more formal style.
* The mirage story is on p. 7 of Vol. II:
* "The 15th and 16th were very foggy. We sailed along the coast of
* Tartary at no great distance, and had sight of it at intervals, when
* the fog dispersed a little; but the 16th will be distinguished in our
* journal by the most complete illusion that I ever witnessed since I have
* been at sea.
* "At four in the evening the most beautifully clear sky succeeded the
* thickest fog. We discovered the continent, which extended from west by
* south to north by east; and very soon after, to the south, an extensive
* land, running west towards Tartary, so as not to leave an opening of
* 15° between it and the continent. We distinguished the mountains,
* the valleys, and all the particulars of the land; and could not conceive
* how we had entered into this strait, which could be no other than that
* of Tessoy, the search after which we had given up. In this situation
* I thought it advisable to haul our wind, and steer south-south-east.
* But soon these hills and valleys disappeared. The most extraordinary
* fog-bank I had ever beheld was the cause of our illusion. We saw it
* disperse; it's shapes, it's colours, ascended, and vanished in the region
* of clouds; and we still had day-light enough left to remove every doubt
* about the existence of this fantastic land. I sailed all night over
* the space of sea it had appeared to occupy, and at day-break nothing of
* it was visible, though our horizon was so extensive, that we distinctly
* saw the coast of Tartary upwards of fifteen leagues distant."
* [NOTE: the abnormally large distance to the horizon shows that inversion
* conditions were still present.]
* The previous inversion observation appears in this edition on p. 537
* of Vol. I:
* "The sky was clear and serene, but it grew very black, and I was
* obliged to stand off the shore, that I might not be embayed by the
* easterly winds. If the clouds did not give us warning of this change,
* we had an indication of it, which we did not understand, and which it
* is not perhaps easy to explain. The men at the mast-head cried out,
* that they felt burning vapours, resembling those of the mouth of an
* oven, coming in puffs every half minute. All the officers went to the
* mast-head, and felt the same heat. The thermometer at that time was
* at 14° upon deck. We sent one up to the cross-trees, and it rose
* to 20°. These puffs of heat, however, passed with great rapidity,
* and in the intervals the temperature of the air did not differ from that
* of the temperature of the level of the sea."
* Note: this edition has the dates in the margins, like the original.
* early report of SUPERIOR MIRAGE, by Vince:
* ``The uncertainty of the refraction of the air near the horizon has long
* been known to astronomers, the mean refraction varying by quantities
* which cannot be accounted for from the variations of the barometer and
* thermometer. . . .''
* ``In fact, the images were visible, when the whole ship was actually below
* the horizon. . . . The discovery of ships in this manner might, in some
* cases, be of great importance. . . .''
* ``As the phenomena are very curious, and extraordinary in their nature, . . .
* They appear to be of considerable importance; as they lead us to a
* knowledge of those changes to which the lower parts of the atmosphere are
* sometimes subject. . . . it might throw further light upon this subject,
* and lead to useful discoveries respecting the state of the atmosphere. . . .''
*
* This was the Bakerian lecture.
* According to the paper's title, Vince was the Plumian Prof. of Astronomy
* & Experimental Philosophy (i.e., physics) at Cambridge.
* The Décade Philosophique meeting abstract of Monge's lecture
* The full title is "La Décade Philosophique, Littéraire et Politique"
* and the publication date is 10 Nivôse = Dec.30, 1798. The article is headed
*
* Institut d'Égypte
*
* and on p. 2 is the sub-head:
*
* Copie des procès-verbaux des séances de l'Institut
* d'Égypte, envoyés à l'Institut national de France
*
* followed by the account of the first meeting, on 6 Fructidor an VI.
*
* The minutes of the second meeting (11 Fructidor) begins on p. 4, with
* Monge's abstract beginning there and continuing to p. 5. The third
* meeting (16 Fructidor) begins near the foot of p. 5. Later meetings
* continue through p. 11.
*
* Available at Gallica:
* https://gallica.bnf.fr/ark:/12148/bpt6k5616321s/f11.item.r=mirage
* The Ann.Chim. lecture abstract of Monge's mirage memoir
*
* "A la mer, il arrive souvent qu'un naivre appercu de loin, paroit
* tout-à-fait dessiné dans le ciel, et n'être point supporté par l'eau. (1)"
* ------------- (the footnote says): -------
* (1) Cette illusion optique nous paroit avoir quelque rapport avec ces
* apparitions dans la mer et dans l'air pres du phare de Messine, connus
* sous le nom de fée Morgan , dont il est fait mention tom.XXV de ces
* Annales, pag. 80. Note des Rédacteurs .
* [This is a brief mention of Nicholson's translation of Minasi.]
* ------------------------------------------
* "Un effet analogue a frappé tous le Francais pendant la marche de l'armée
* à travers le désert. . . .
* "Le cit. Monge attribue cet effet à la diminution de densité de la
* couche inférieure de l'atmosphère. Cette diminution dans le désert est
* produite par l'augmentation de température qui est la résultat de la
* chaleur communiquée par le soleil aux sables avec lesquels cette
* couche est en contact immédiat. A la mer, elle a lieu lorsque, par des
* circonstances particulières, telles que l'action des vents, la couche
* infèrieure de l'atmosphère tient en dissolution une plus grande
* quantité d'eau que les autres couches. Dans cet état de choses, les
* rayons de lumière qui viennent des parties basses du ciel, étant arrivés
* a la surface qui sépare la couche la moins dense de celles qui sont
* au-dessus, ne pénètrent pas dans cette couche; ils sont réfléchis, et
* vont peindre, dans l'œil de l'observateur, l'image du ciel. . . . "
* So here we have water vapor and a fictitious reflecting "surface",
* from the very beginning.
*
* The text is almost identical to that appearing in Décade Philosophique,
* An 7, No. 10, pp. 4-5, where it is part of the report for the second
* meeting of the Institut d'Egypte.
*
*
* Page 207 is headed:
*
* E X T R A I T
*
*Du mémoire lu à la séance de l'institut
* du Caire, du 11fructidor, an 6;
*
* Par le cit. M O N G E
*
* (That date is 28 August 1798.)
*
*
* However, the issue of Ann. Chim. in which this reprint appears is dated
* 30 Nivôse = 19 janvier 1799.
*
* Available at Gallica:
* https://gallica.bnf.fr/ark:/12148/bpt6k65712092/f7.item.r=mirage
* The text of Monge's mirage memoir
* Monge says that the mirage in the desert may be due to heat, but that
* the mirage at sea is different: "En effet, l'air a la faculté de
* dissoudre l'eau, et même d'atteindre le point de saturation, sans perdre
* sa transparence; et Sassure a fait voir due la pesanteur spécifique de
* l'air décroit à mesure qu'il tient une plus grande quantité d'eau en
* dissolution. Lors donc que le vent qui souffle en mer apporte un air
* qui n'est pas saturé d'eau, la couche inférieure de l'athmosphère qui
* est en contact avec la surface de la mer, dissout de l'eau nouvelle, et
* se dilate. Cette cause, jointe à la légère augmentation de température,
* peut enfin amener les circonstances favorables au mirage, et produit en
* effet celui que les marins observent assez fréquemment." (p. 45)
* This differs by many minor changes in spelling and punctuation from
* the final version (below), which has the addendum on rainbows.
* According to Gallica, this was published in 1799. The title page
* says only " An VII ". This first volume was supposedly printed every 10
* days; as Gallica dates the volume at Jan. 1, this second number might
* have been printed on Jan. 11, 1799. The signature footers say "1.er
* Trimestre, AN 7."
* GASPARD MONGE explains the INFERIOR MIRAGE as total internal reflection,
* and reports REFLECTED RAINBOWS
* He leans very heavily on total internal reflection, and attributes
* the inferior mirages seen at sea to the effect of water vapor on the
* refractivity of air, confusing optical "density" with mechanical density.
* ". . . ce phénomene pourroit ne pas être ignoré des habitants du
* département des landes; mais il est très connu des marins, qui
* l'observent fréquemment à la mer, et qui lui ont donné le nom de
* Mirage ." (p. 65) [Cf. Le Gentil (1789) for "se mirer".]
* He takes the internal-reflection picture very literally, repeatedly
* referring to "la surface qui sépare la couche inférieure et dilatée
* de l'atmosphere de la couche plus dense qui est au-dessus d'elle" (p. 71)
* and "la surface réfléchissante, qui sépare les deux couches d'air des
* densités différentes, n'est ni parfaitement plane" (p. 73). This
* mistaken idea was immediately challenged by Reinecke (see below), and
* by Wollaston (1803). Nevertheless, we still see it stated in physics
* textbooks today.
* This volume simply says "An VIII" on the title page, and no more
* precise date is indicated. As most of that year in the Republican
* calendar was in Gregorian year 1800, I adopt "1800" as the date.
* This also is the date in most library catalogs.
* NOTE: the spelling "phénomene" (without a grave accent) is used
* consistently throughout; it is not a typo here in his title.
* Monge's memoir translated into English
* The translator is not named, though there is an Advertisement of the
* Translator -- in which we read that "Some of the Memoirs bear the marks
* of being hastily composed, but . . . no omissions or alterations have been
* made by the English Editor, which might render the translation any thing
* else than an accurate and complete copy of the original Work."
* Brief mention of Monge's memoir in a review of the whole "Memoires"
* We are interested only in the lines on p. 1850:
* "Abhandlung über die unter dem Nahmen Mirage bekannte optische
* Erscheinung, von G. Monge. Mit der Beschreibung dieses Phänomens wird
* man besser zufrieden seyn, als mit der Erklärung, die M. davon zu geben
* versucht."
* This is the 186. St. of 1800.
* Available at Google Books.
* Interesting REVIEW of mirages by Dr. JOHANN CHRISTOPH MATTHIAS REINECKE
* He begins with the Fata Morgana, "or the Castles in the Air of the
* fairy Morgana," immediately naming Angelucci, Kircher and Scotus as
* the older writers who have tried to offer descriptions and explanations.
* Of the newer writers, he mentions only Minasi, whose work he knows only
* from Nicholson's 1797 extract in the Philosophical Journal. Fortunately,
* it includes Minasi's illustration of the whole thing, which is copied
* here as Tafel I. So it's necessary to translate Minasi's description
* from the English. . . . And in doing so, he refers to the details of the
* engraving.
* Among other things, he points out the Sun low in the sky at the
* left edge of the image -- a detail that seems to have escaped all other
* students of the image. Evidently, he thinks Minasi's "45 degrees"
* refers to an azimuthal angle, not a solar altitude. (Note his remark
* on p. 209 about 9 a.m. being the favorable hour.)
* He also points out the impossibility that the city depicted could be
* Reggio, as it is Messina that lies on the opposite shore. The doubling
* of the images must make the city unrecognizable; and the random angles
* at which the "reflected" towers stand, without falling down, make them
* "true fairy-castles" which could "exist on the coast of neither Italy
* nor Sicily". Then comes a salient point: "Only through precise drawings,
* both of the phenomenon and of the view of the city of Reggio from the
* seaside, which, as has happened in the present copper engraving, were
* placed next to each other, could one part of the riddle and the origin of
* these fairy-castles be found." So he understood the need for photographic
* evidence decades before photography was invented, and centuries before
* photographs of Fata Morgana displays were actually obtained. "Here I
* regret that Minasi is not more detailed." But he generally accepts
* Minasi's account of both the phenomena and their cause as correct.
* So he thinks the sides of the waves generally have an inclination to
* the horizontal of 45 degrees, and supposes that the inclination of the
* mean surface can be similarly large, so that the waves could actually
* have vertical surfaces (as shown in Fig.1 of Tafel II) -- thus making
* the vertical mirror that Minasi imagined.
* He then gives a German translation of Nicholson's English translation
* of Minasi's Italian. This is a different German translation of
* Nicholson than the one published by Gilbert two years later (see the 1802
* entries below). Gilbert clearly used parts of Reinecke's discussion in
* making his own, and cites Reinecke -- though not by name.
* In the end, Reinecke tries to explain how Minasi's wave-facet scheme
* might work because of the shape of the Strait. It is all very contrived.
* However, on p. 206, there is the useful idea that Minasi probably meant
* Puglian miles, of 7000 Neapolitan palms each, in specifying distances.
* Apart from the supposed interactions of local causes, Reinecke admits
* that "it would always appear striking that this phenomenon is not also
* visible at other coasts . . . ". (p.210) In searching for examples, the
* best he can find is Wetterling's 1788 discussion of the Erhebung and
* the Seegesicht . [His accouunt of the virtual "cliffs" seen in Sweden
* in August, 1774, seems quite similar to Forel's identification of a
* "striated zone" as the hallmark of the Fata Morgana a century later.]
* Surprisingly, Reinecke knew of accounts by de Ferrariis and others
* of similar mirages in southern Italy, citing Giovene as well.
* Having identified the Seegesicht as being at least related to
* the Fata Morgana, Reinecke turns to looming. (p.219) Unfortunately,
* he says that it is the same thing as Kimmung , which is the appearance
* of floating or suspension produced when a strip of miraged sky is seen
* beneath objects at the apparent horizon -- but in an inferior mirage;
* the inverted image seems to hang down from the fold line. (P&E call
* this effect "Schwebung oder Kimmung" on their p.137). However, Reinecke
* correctly describes Erhebung as making "objects that lie under the
* horizon, or are hidden by other objects, become visible above it."
* He adds that the phenomenon is mostly observed on the Baltic Sea.
* As examples, he offers both Wetterling's discussion and that of
* Prof. Büsch (in his Tractatus .)
* His first impression was that just one kind of phenomenon had been
* called the Erhebung ; but on closer examination, he found that "many of
* them, especially those in which the images of ordinary objects appear cut
* off in the air, are really Morganas ." He cites examples from Wetterling
* that show extreme vertical exaggeration and rapid variations, noting the
* similarity of circumstances (position of the Sun, calm air) and location
* (near the sea), and compares these with Giovene's Lavandaja observations.
* But he is puzzled: if the circumstances and locations are so similar,
* why are the appearances so varied? (pp. 220-221)
* NOTE: as Reinecke was primarily a cartographer, geographer, and
* paleontologist, his ignorance of physics in general and optics in
* particular is to be expected; so his acceptance of Minasi's nonsense
* "theory" is not surprising. Given this ignorance, his connection of
* looming with Fata Morganas is a substantial accomplishment.
* The first page of this number says "V Bds. drittes Stück. März 1800."
* in italics; and then "A B H A N D L U N G E N".
* No author is named in this issue; but his identity is revealed in the
* July issue. This Abhandlung is numbered I. After the title is another
* italic note: "Hierzu gehören die Kupfer --- Tafeln I und II."
* I do not have a copy of these plates. However, they have been
* reprinted in Marcello Séstito's "Fata Morgana" book, which cites these
* papers by Reinecke, Büsch, and Monge, translating them all into Italian.
* Special thanks to Marcella Giulia Pace for bringing these important
* references to my attention!
* Reinecke's discussion of mirages is commented on by Büsch, followed by
* Reinecke's rejoinder and translation of Monge's article, and Reinecke's
* further comments on Monge. I list these components separately here,
* as they are assigned separate numbers in the Abhandlungen. All are
* in the Appendices to Séstito's book, translated into Italian.
* The first page of this number says "VI. Bds. erstes Stück. Julius 1800."
* in italics; and then "A B H A N D L U N G E N".
* Here is Abhandlung I., divided into four numbered sub-sections; they
* are sometimes cited by the collective title of the whole Abhandlung:
*
* "Fernere Beyträge und Bemerkungen über die Fata Morgana, das Seegesicht
* und die Erhebung."
*
* Büsch had himself already read Minasi's Büchlein some years before,
* and thinks it's better to see the original than Nicholson's English
* translation. And he doesn't think much of Minasi's original, either:
* "There is only one place in the book, p. 74, that makes me believe he
* had seen the phenomenon himself. But instead of describing it exactly,
* he immediately turns to the glorification of God. . . . So I almost
* believe that he himself knows no more about it than his father had
* told him. Then, it seems, this marvel appears only rarely, though even
* so M. produces a theory whereby it should appear very often and regularly
* under his defined conditions." (p.4)
* "Such a marvel should, if it's possible, be seen from more than one
* place, and from different viewing points and distances. But that should
* be easy, as it includes such a great space in the atmosphere.
* "It is a phenomenon of the atmosphere, so M. should have guessed to
* observe the state of the atmosphere at the same time, even if only by
* the height of the barometer. A thermometer would have been no trouble
* at all.
* "All this didn't stop him from devising a theory, but which? It
* should 'come from the different currents that meet in the Strait of
* Messina, pressing hard, and working against one another, create a
* mirror-smooth surface.' But that would be remarkable in a strait where
* a Scylla and Charybdis make currents that already the Ancients
* described as dangerous. But M. has surely never attentively observed
* a body of water in which several streams encounter one another. We have
* several such places in the Elbe , where the water is always restless,
* even if it is moved by no wind from the side. . . . " (p.5)
* After describing those examples in detail, he asks: "Should Nature be
* so completely different in the Strait of Messina, and even form a smooth
* concave mirror whose figure would have to be not just spherical, but
* that of a hollow cylinder?" (p.6)
* Büsch then adds a few more comments on "theorifying", and thanks the
* author [Reinecke] for mentioning his own Latin thesis on mirages. Then
* he returns to the Fata Morgana:
* "In regard to the Fata Morgana , one of three [sic] things must be true.
* 1) Either the whole phenomenon has been described falsely until now,
* or magnified through the desire for the miraculous. . . . Minasi is free
* of such monks'-dreams, but he seems to me not to have seen quite clearly
* yet. 2) But if Minasi has seen correctly, even if it were only one
* observation, then the phenomenon is something completely different from
* what I have seen and described a hundred times. Then we could completely
* lay the Fata Morgana aside, and so it will come to the point that
* Teutons will examine the matter more closely with Teutonic diligence,
* and seek to explain the results, which certainly lie in the study of
* the determination of the refraction. For no one but Gruber and me has
* yet thought to give an explanation of how it occurs over dry land ."
* He then relates some of his own mirage observations made while
* traveling on the Baltic coast. These were clearly inferior mirages,
* "which had been so remarkable to the French, but from which they learned
* nothing." [So much for Monge!] "I saw them at all hours of the day,
* and not a single time with different or unfamiliar circumstances. It
* amuses me when I read so many differences in the description. But then
* I think: 'The man did not see what you saw, or his power of imagination
* has added what yours did not, because you yourself know to keep it in
* bounds.'" (p.9)
* He then mentions Humboldt's observations of mirages, and says that he
* has just received the first part of the British Transactions for 1799
* with the observations by Vince; but he was not able to understand
* Vince's figure. [Obviously, because he only is familiar with inferior
* mirages.] (p.11)
* On the next pages is an amusing anecdote about showing the mirage to
* Graf von Czeczeny from Hungary, while traveling in the Harkshaide [sic]
* on the road from Hamburg to Kiel, in July, 1790. This is followed on p.14
* by a brief mention of the 1798 publication of Latham's observation of
* looming at Hastings.
*
* A footnote on the first page explains that the unsigned review in the
* March issue was written by Dr. Reinecke, a frequent contributor.
* Büsch's letter here is cited in a footnote on p. 133 of Pernter & Exner
* (1922), where it is attributed to Bertuch and Gaspari, the publishers of
* Allgem. geogr. Ephemeriden; Reinecke is not mentioned. Likewise, in
* Gilbert's 1802 discussion of Minasi (see his note on p.30 there).
* This must be nearly the last thing Büsch wrote; he died August 5, 1800.
* Reinecke's reply to Büsch
* Reinecke begins by quoting Büsch, and correcting the "3 for 2" error
* on p.7. He declares that the second is obviously the correct choice.
* And he emphasizes that Büsch has a single observation that seems to have
* some similarity with the Fata Morgana in his Tractatus .
* "That Minasi observed superficially may well be true; but where are
* the better observers?" [Note: Minasi was a medicinal botanist, not a
* physicist.]
* The first page of this number says "VI. Bds. erstes Stück. Julius 1800."
* in italics; and then "A B H A N D L U N G E N".
* This is part 2 of Abhandlung I.
* Reinecke's translation of Gaspard Monge's paper in Memoires sur l'Egypte
* There is a footnote to the title word "Kimmung" that says:
* "Gewönlich Erhebung , Franzos. Mirage , in Niederteutschland
* Währkatten , Updracht , Holl. Opduining , Schwäd. Hägring ."
* The first page of this number says "VI. Bds. erstes Stück. Julius 1800."
* in italics; and then "A B H A N D L U N G E N".
* This is part 3 of Abhandlung I.
* Reinecke's additional comments as translator of Monge
* Reinecke does not mince words: "The above theory requires a correction,"
* is his first sentence. ["Die obige Theorie bedarf einiger Berichtigung."]
* (Cf. Büsch's similar remarks in his 1783 "Tractatus".)
* Of Monge's "einzigen bestimmten Fläche", he says:
* "Eine so genau abgeschnittene Fläche findet aber, wie auch schon Hr.
* Prof. Büsch bey Gelegenheit der Gruberschen Erklärung desselben
* Phänomens bemerkt, in der Natur nicht statt; sondern die Dichtigkeit der
* Luft nimmt fortgehend und allmählich ab oder zu, und es ist kein Grund
* vorhanden, warum sie an einer Stelle mehr als an der andern reflectieren
* sollte. Statt einer einfachen Reflexion erleidet vielmehr ein
* Lichtstrahl, wenn er durch ein Medium von abnehmender Dichtigkeit geht,
* auf jedem Puncte seines Weges eine Brechung, und beschreibt daher eine
* krumme Linie, die, je nachdem die Dichtigkeitszunahme schneller oder
* geringer, und der Weg des Lichtstrahls länger oder kürzer ist, von
* verschiedener Art seyn kann." He goes on to explain that the usual
* state of the atmosphere makes the rays concave toward the Earth; but
* if we invert the usual decrease of density upward, the rays will be
* concave upward and turn their convex sides to the Earth -- "obgleich
* keine wirkliche Reflexion erfolgt."
* "Dies ist nun auch das Phänomen, von dem Hr. Prof. Büsch in
* seinem Tractate und in obigem Briefe handelt. Seine Erklärung, die
* Monge nicht gekannt zu haben scheint, weicht von der hier gegebenen
* ganz ab, aber wie? --- Nach Hr. Büsch erklärt sich alles aus der
* gewöhnlichen --- verstärkten horizontalen Strahlenbrechung, statt
* dass wir es eben aus der umgekehrten horizontalen Strahlenbrechung
* erklären." He goes on to explain that either explanation will work; that
* is, he sees that it is the change in the ray curvature that is needed
* to produce the inverted images. Both explanations produce "the same
* phenomenon, a variation of the horizon." Büsch's model should produce
* "eine Erhebung der Gegenstände über den Horizont"; in Reinecke's
* model, "die Gegenstände müssen . . . unter den Horizont hinabsinken."
* He decides that Hebung is the usual case in northern latitudes, and
* thus accounts for Büsch's observations of looming.
* So he notes the problem: "Monge hat keine Winkelmessungen
* angestellt, und überhaupt auf diesen Punct, wie es scheint, nicht
* Rücksicht genommen." So Reinecke recognized that the absolute values of
* the altitudes near the horizon are needed to understand the full details
* of the mirages. The DIP is an essential feature of mirages.
* "Inzwischen ist es sehr zu wünschen, dass Beobachter, die sich in
* Rücksicht ihres Wohnorts in einer dazu günstigen Lage befinden, ---
* denn bey Erscheinungen, die den Beobachter ganz unvorbereitet auf der
* Reise überraschen, ist das nicht zu erwarten, --- ihre Beobachtungen
* mit Winkelmessungen, und was sich ohnehin versteht, mit Thermometer-
* und Barometer-Beobachtungen verbinden mögen, wie schon Hr. Büsch am
* Schlusse seines Tractats empfiehlt, weil ohne diess nothwendig manches
* schwankend bleiben muss."
* Reincke's perceptive remarks here show a much better understanding of
* the mirage problem than his earlier comments would suggest.
*
* The first page of this number says "VI. Bds. erstes Stück. Julius 1800."
* in italics; and then "A B H A N D L U N G E N".
* This is part 4 of Abhandlung I.
* Available from Google Books:
* https://www.google.com/books/edition/Allgemeine_geographische_Ephemeriden/OJgPbBBjqpQC?hl=en&gbpv=1&dq=Monge+Reinecke+mirage&pg=PA15&printsec=frontcover
* and
* https://www.google.com/books/edition/Allgemeine_geographische_Ephemeriden/aRiKHZFw3zUC?hl=en&gbpv=1&dq=Monge+Reinecke+mirage&pg=PA15&printsec=frontcover
* EARLY MIRAGES; DISTORTED MOONRISE
* extracted and translated from:
* Jo. Geo. Büsch tractatus duo optici argumenti, Hamburgi 1783, 132 S. 8.
* "Ich bemerkte dieses Phänomen schon in meiner Jugend bey den
* Ueberfahrten von Hamburg nach dem eine Meile entlegnen Harburg, wo mein
* Grossvater lebte. Wenn der Wind die Wellen mitten im Strome ziemlich
* heftig um das Schiff bewegte, schien das Wasser am Ufer vollkommen ruhig
* zu seyn, gleich einer Spiegelebene. Dieses komme, sagten mir die
* Uferbewohner, von den Untiefen am Strande her; allein, wenn wir eine Höhe
* erstiegen, und von da nach dem entgegengesetzten Ufer sahen, war auch das
* Wasser voll Wellen."
* (cf. Abbott, 1854, who reports the same phenomenon in India!)
* (also, Forel, p. 526 of his 1895 monograph; and Manning, 1912.)
*
* includes a distorted moonrise: "Der Mond, der beynahe voll war, ging
* auf, wie ihn Fig. 6 zeigt. Als ich die anderen Passagiers fragte, ob
* ihnen nicht etwas besonderes am Monde vorkomme, antwortete einer:
* `Meiner Treu, er gleicht einem umgestürzten Nachtgeschirr.'"
* [See Büsch, Tractatus duo (1783) for the original quote in English.]
*
* Prof. Johann Georg Büsch (1728 - 1800) taught at the academic
* Gymnasium in Hamburg. About 1780 he allowed Reinhard Woltman to attend
* his lectures and use his extensive library. Woltman in turn became the
* supervisor of Heinrich Wilhelm Brandes, who was in charge of the water
* works on Neuwerk in 1794-95, and was recommended by Woltman to the post
* of "Deichconducteur" in Eckwarden in 1801, where he continued Woltman's
* observations of refraction phenomena.
* This is Part 3 of Band 3, mostly devoted to refraction and mirages. It
* begins with a German translation of Huddart's paper on dip, followed by
* General Roy and Dalby's work. The issue date is not known, but Gilbert's
* preface to the whole volume is dated "den 2ten Februar 1800".
* HUDDART translated by Gilbert
* With the usual copious comments by Gilbert! Already on p. 259, he
* inserts a footnote referring to Gruber and Büsch, "die der Leser im
* nächsten Bande der Annalen in kurzen Auszügen finden wird".
* This volume of Gilb. Ann. is available at
* https://www.google.com/books/edition/Annalen_der_Physik/_3zqQ4mRhO8C?hl=en&gbpv=1&dq=Gilbert+Annalen+Physik+1800+Huddart&pg=PA265&printsec=frontcover
* EARLY MIRAGES
* summaries of the work of others by Ludwig Wilhelm Gilbert:
* 1801 review of Monge's final paper
* Buried in a long paragraph on a variety of technical publications,
* we find: "One other optical phenomenon has been illustrated by the
* publications of the present year, viz. what is called the Mirage, in the
* Collection of Memoirs published by the Philosophers who followed Bonaparte
* to Egypt. The author is M. Monge, whose account is neither very clear
* nor scientific." (This follows a mention of Wollaston's 1800 paper.)
* As this is mentioned under "Domestic Literature", I suppose it is based
* on the official English translation of the Memoirs published in London.
* Full title: "The New Annual Register or General Repository of History,
* Politics, and Literature, for the Year 1800."
* NOTE: the several sections of this volume are separately paginated.
* This is in the last one, which starts with "Biographical Anecdotes and
* Characters"; its sub-section "Domestic Literature of the Year 1800" runs
* from p. 225 to p. 336. The subsection "Foreign Literature . . . " begins
* on p. 337. No authors' names are given.
* EARLY EXPERIMENTAL DEMONSTRATION OF MIRAGE
* Abbé Tobias Gruber (Grüber?) -- see his 1786 paper.
* Gilbert says this is an extract of Gruber's "Physikalischer Abhandlung
* über die Strahlenbrechung und Abprallung auf erwärmten Flächen" in
* Abhandlungen der böhmischen Gesellschaft der Wissenschaften, B.II, (1787).
* Pernter and I both have 1786 for its date; Gilbert's date might be the
* actual year of publication -- or that of the Dresden offprint.
* Büsch's reference to Gruber in his comments in Vol. 6 of A.G.E.
* [see above], and his contributions to Gilbert's Annalen in the next few
* years suggest that Gilbert reprinted Gruber's work at Büsch's suggestion.
* Gilbert's preface ("Vorredé) to the volume is dated "de 2ten Februar".
* This begins the fourth part of Band 3.
* QUANTITATIVE MEASUREMENTS of MIRAGES and VARIABLE REFRACTION
* Reinhard Woltman (Not "Woltmann", says Pogg.)
* [It seems that Woltman was Brandes's supervisor in 1794-95.]
* Gilbert attributes the term "Spiegelung" to Woltman.
*
* Mirages visible in RAIN and on overcast days (cf. Ashmore, 1955):
* ". . . selbst im Regen verschwindet sie nicht eher, als bis die
* Undurchsichtigkeit der Luft die Aussicht in die Ferne verhindert.
* Ueberhaupt ist die Erscheinung (wenigstens um Cuxhaven) weit häufiger
* als man sie mit blossen Augen gewahr wird, indem an dunkeln Tagen der
* Luftstreifen, welcher die Gegenstände von der Erde zu trennen scheint,
* nicht so als an hellen Tagen ins Auge fällt." (p. 399)
*
* REDUCED SIZE of image attributed to reflection at a convex surface (p.403):
* "Bey unserm Phänomen sind . . . die Bilder allemal beträchtlich
* kleiner , als ihre Objecte." (Cf. Bravais, 1853; Riccò et al., 1888)
*
* VARIATIONS:
* "Auch die astronomische Horizontalrefraction würde daher wenigstens
* um eben so viel, d.i. etwa um 1/6 ihrer ganzen Grösse veränderlich und
* ungewiss seyn." (p. 421)
*
* Gruber's footnote, pp. 429-430, on CORRELATION of DIP & MIRAGEs:
* ". . . so ist bey allen Spieglungen ohne Ausnahme Depression , so wie bey
* Spieglungen aufwärts, Hebung über diese scheinbare Horizontallinie."
* See Gruber's paper on this in the following item.
*
* VERTICAL STRIPES at the fold line of SUPERIOR MIRAGES:
* "Zuweilen trennt ein Luftstreifen das verkehrte Bild von dem darunter
* stehenden Gegenstande; doch stossen häufiger Bild und Gegenstand
* zusammen , und vermischen sich so, dass keins von beiden kenntlich ist,
* und das Ganze wie eine hohe Seeküste, mit vielen senkrechten Strichen,
* erscheint." (p.430)
*
* Relation of "seeing" (TURBULENCE) to inferior mirage (pp. 432-433):
* "Die Bilder der Spieglung unterwärts sind sehr unbeständig und
* wandelbar; sie werden bald grösser, bald kleiner, bald in Stücken
* getrennt, und sind zuweilen eine Zeitlang in steter Bewegung."
*
* TEMPERATURE DIFFERENCE between AIR and WATER:
* ". . . allemal, wenn das Wasser um 2° Fahrenh. oder mehr wärmer als
* die Luft war, eine Erniedrigung der Strahlen, die sich über die
* Wasserfläche erstreckten, und (vorausgesetzt, dass die Gegenstände
* sichtbar waren) eine Spiegelung herabwärts stat find. War dagegen das
* Wasser um 2° F. kälter als die Luft, so fand Hebung der Strahlen
* und nie eine Spiegelung herabwärts statt." (pp. 434-435)
* SEASONAL and DIURNAL variations: p. 435.
* OMEGAs are described, p. 438:
* "Sieht man die Sonne oder den Mond aufgehn oder untergehn , so
* giebt ihre Gestalt ein untrügliches Merkmal, ob Hebung oder Senkung
* statt findet. Im letztern Fall scheint die Sonnen- oder Mond-scheibe
* nicht rund, sondern in die Länge gezogen. Ein Theil derselben spiegelt
* sich unterwärts; das umgekehrte Bild kann 1/8 bis 1/4 des Durchmessers
* betragen, und es ist, als ob an dem auf- oder untergegangnen Theile der
* Anfang einer andern Scheibe angesetzt wäre." (p. 438)
*
* Gilbert's footnote on p. 397 says this is an extract of two works of
* Woltmann's "under the above title, one still unpublished, reported in
* the Götting-gelehrten Anzeigen J. 1796, St. 82; and from Woltmanns
* Bemerkungen über ein (scheinbar) katoptrisches Phänomen , welches
* an den Gegenständen nahe am Horizont nicht selten sichtbar ist , . . . in
* den Neuen Abhandl. der kön. böhmischen Gesellsch. d. Wiss. B. 3.
* Prag 1798. S. 67-97. 4."
* Note that Gilbert prints double-s as a long followed by a short s.
* This continues the fourth part of Band 3.
* EARLY THEORY OF MIRAGE; connection of MIRAGE and DIP
* Abbé Tobias Gruber (Grüber?) comments on Woltman's preceding paper;
* possibly an extract of his 1793 "Theorie . . . Senkung und Hebung" ??
* He uses ray diagrams, assuming a flat Earth, and thereby has some
* difficulties in explaining the reduced size of the inverted images in
* inferior mirages, and the vertical striation associated with superior
* ones.
* There is also extensive editorial discussion of terminology in Gilbert's
* long footnotes; e.g., he criticizes Gruber and Woltman for using the
* words "Abprellung" and "katoptrisches" for inferior mirages: "allein
* da sie das wirklich nicht, sondern ganz und gar eine dioptrische
* Erscheinung ist . . . ". (p. 441)
* This continues the fourth part of Band 3.
* a simple case of LOOMING in the mountains
* Gilbert unaccountably makes more of this than it deserves. His final
* footnote contains: "Auch bei uns, mitten im Deutschland, ist also die
* Fata Morgana zu Hause, obwohl bei weitem seltener als in dem heissen
* Unter - Italien und unfern der See. Denn dass die wundervolle
* Fata Morgana zu dieser Klasse ungewöhnlich starker Refractionen
* gehört, glaube ich in einem der folgenden Stücke der Annalen ziemlich
* ausser Zweifel setzen zu können." But he recognizes that it's similar
* to Latham's observation.
* This may be the earliest MIS-USE of "FATA MORGANA" for a simpler case.
* In the fourth part of Band 5.
* William Hyde WOLLASTON's paper on mirage theory:
* Wollaston re-invents Hooke's (1665) two-liquid demonstration here.
* He distinguishes between "two opposite states of the atmosphere" that
* produce double or triple images; he also notes what we would call
* looming, and explicitly mentions mirages on roads.
* His laboratory experiments on liquids showed the focusing effect:
* ". . . adjacent portions of the converging rays will form a focus, beyond
* which they will diverge again; and the varied medium will produce
* effects similar to those caused by a medium of uniform density having
* a surface similar to the curve of densities . . . ." (p. 242)
* "When an oblique line . . . is viewed through any variable medium . . . ,
* it appears bent into different forms . . . .
* "If it be at the distance of the principal focus, one point of it is
* bent into a vertical line . . . ." (p. 244)
*
* He also discovers the laminar sub-layer, via the third image:
* "To explain why red-hot iron occasions two [additional] images, while
* solar hear produces but one, I imagine that the intense heat in the
* former case rarefies the air for some small distance uniformly, and
* thereby affords the same series of variations as between other fluids
* of uniform density; but that, in the latter, the heat is conveyed off
* as fast as it is generated . . . ." (p. 248)
* On the next page, he mentions that "a level open road" is best for
* observing what we would call inferior mirages. He also uses "a pocket
* telescope magnifying about 16 times".
* Jean André de Luc's inferior-mirage observation, and disbelief
* A curious paper: "Es ist allgemein bekannt, dass am Ufer der Seen und
* der breiten Flüsse und am Strande der Meerbusen eine gewisse optische
* Täuschung oft statt findet, wenn der Zuschauer sich auf einem erhöhten
* Standpunkte befindet; er sieht nemlich alsdann unter gewissen Umständen
* das entgegengesetzte Ufer wie in der Luft schwebend, und man pflegte
* dieses Phänomen auf die Strahlenbrechung zu reduciren: ich glaube aber
* nicht, dass es von dieser Ursache herrühre."
* He nicely describes the effects of eye height; but manages to convince
* himself the apparent "sky" is just a band of haze, "eine Dunstschicht",
* that manages to be indistinguishable from the sky. (This seems incredible
* to anyone living in a dry climate, but is perhaps not so far-fetched
* for someone living in hazy Germany.) At the end of the 10th page
* of the paper (p.177), he lets the cat out of the bag: "Ich zweifle
* kaum dass dies der wahre Grund aller Erscheinungen dieser Art wirklich
* sei, und zwar um so weniger, da ich nie habe begreifen können, wie
* Strahlenbrechung etwas dergleichen hervorbringen könnte."
* The observation was made over a peat-bog; the miraged trees were
* "ohngefahr eine deutsche Meile" away (6 or 7 km).
* The GNF had a number of well-known members, including Adelbert von
* Chamisso, Alexander von Humboldt, Adolf Traugott, and Johann Elert Bode.
* Reuss fails to give the year, but other citations to this volume say
* 1801 [confirmed by e-mail from Hans-Ulrich Raake of the
* Universitätsbibliothek, Humboldt-Universität Berlin (30 July 2002).]
* Prof. De Luc was Swiss.
* Gilbert's translation of Wollaston's 1800 paper, with copious notes:
* Gilbert's version of Giovene's observations, heavily annotated
* Here Giuseppe Maria Giovene is Germanized to "Johannes"; the whole
* thing is taken from Zimmermann's "Allgemeiner Blick auf Italien" (1797).
* A good first-hand account of a Fata Morgana observation from near
* Molfetta, on the Adriatic coast (about 300 km north of Reggio):
* "Die von mir selbst beobachteten Phänomene dieser Art schreibe ich
* wörtlich aus meinen Journalen ab; von den übrigen theile ich die
* Nachricht meiner Correspondenten unverändert mit.
* "Ich befand mich am 9ten Februar 1790 auf einem kleinen Landhause,
* wo ich mich wegen des freien Horizonts vorzüglich gern aufhalte.
* Die Tagen vorher waren heiter gewesen, und es hatte ein mässiger
* Nordwestwind geweht. Der ausnehmend schöne Winterabend lockte mich
* ungefähr eine halbe Stunde nach Sonnenuntergang an ein Fenster, das
* sich gerade nach S.S.O. öffnet. [Giovene's original Italian indeed has
* "S.S.O."; but "O" stands for "ovest"; so the directions are wrong here.]
* Die Luft war so still, dass der Rauch von den Städten Terlizzi , Ruvo
* und Corato , auf die ich die Aussicht hatte, sich gar nicht bewegte,
* sondern über diesen Städten wie ein grosser Sonnenschein hing.
* [Certainly "Sonnenschirm" was intended here; this correction is made
* by P&E on p. 164, without comment.] Indem ich am Horizonte umher sah,
* schienen mir an dem äussersten Ende desselben gegen Westen einige Wolken
* aufzusteigen, die etwa 20 Grad einnahmen. Um daraus auf den Wind und auf
* die Witterung des folgenden Tages urtheilen zu können, wollte ich ihren
* Zug beobachten. Sie stiegen bald auf 2° Höhe, fingen dann aber an
* mannigfaltige Gestalten anzunehmen, und dieses Spiel überzeugte mich,
* dass sie ganz etwas anderes waren, als Wolken.
* "Ich bat daher den Doktor T r i p a l d i , einen sehr unterrichteten
* Mann, der mich gerade auf einige Tage besucht hatte, an der fernern
* Beobachtung Theil zu nehmen, und wir schickten uns beide dazu auf das
* sorgfältigste an. Die vermeinten Wolken nahmen alle Augenblicke eine
* andere Gestalt an. Zuerst sahen wir im Hintergrunde eine Menge Palläste
* und Thürme, die eine grosse Stadt vorstellten, so dass wir glaubten,
* vermittelst einer sehr verstärkten atmosphärischen Refraction den
* Flecken Cerignola zu sehn, der in der Richtung lag, jedoch über 8
* deutsche Meilen, (in gerader Linie nur 6,) enfernt war. Allein gar bald
* veränderte sich das Schauspiel: wir sahen zwei Hügel gegen einander
* über, die immer höher und höher wurden, und sich dann in viereckige
* Thürme mit grossen Fenstern verwandelten, wodurch das Licht von der
* Abenddämmerung einfiel. Doch ich kann unmöglich alle die verschiedenen
* Figuren beschreiben, die mit der grössten Schnelligkeit abwechselten.
* "Unsre Verwunderung wurde indess bald noch sehr vermehrt. Die
* Dämmerung war sehr hell, und ich sah verschiedne Mahl Lichtströme
* vom äussersten Horizonte bis zu einer Höhe von 6 bis 7° aufsteigen.
* Ich hielt dieses anfangs für eine Täuschung, allein D. T r i p a l d i
* sah sie gerade so, und der Zeitpunkt, worin wir einen neuen Lichtstrahl
* wahrnahmen, stimmte jedes Mahl vollkommen überein. Wir stellten uns
* darauf vor das eine Fenster, das gerade nach W.N.W. lag, und sahen das
* Phänomen eben so. Die Lichtwellen gingen gerade bis an die Grenzen
* der Dämmerung; da, wo die Dämmerung stärker war, waren sie lebhafter,
* und gegen die Grenzen der Dämmerung zu schwächer. Fünf oder sechs
* lichte Ströme erschienen unmittelbar nach einander, darauf erfolgte
* eine Pause von 1 oder 2 minuten, worauf sich neue Ströme zeigten, und
* während dieses Spiels wechselte eine unendliche Mannigfaltigkeit der
* seltsamsten Figuren am äussersten Rande des Horizonts ab. Dieses schöne
* Schauspiel währte etwa eine halbe Stunde; es verlor an Schönheit, so
* wie die Dämmerung abnahm, und nach 3/4 Stunden war es gänzlich vorbei."
* Giovene points out that such phenomena are not rare in Apulia and
* Lecce province (Terra d'Otranto, the old Japygia). But writers have
* ignored it, except in folklore, with one exception: he cites Antonius
* de Ferrariis (Galatheus) (De situ Japygiæ , 1558) for reporting the
* name of Mutata . (p. 9)
* A useful common observation: "Nach Versicherung der Einwohner des
* Vorgebirges von Lecce ist die Zeit dieser Erscheinung vor Aufgang
* oder nach Untergang der Sonne, und in der Ebene soll man dabei bald ein
* stürmisches Meer, bald eine Stadt, bald einen Wald sehn." (pp. 10-11)
* He also says: "Die Seeleute von Molfetta nennen sie Lavandaja
* (Wäscherinn,) -- warum, weiss ich nicht -- und halten sie für Vorboten
* einer Veränderung in der Witterung. In der That erscheint die
* Lavandaja in ihrer grössten Schönheit, wenn der Wind lange Zeit geweht
* hat und nun eine Stille erfolt. Im Herbste und Winter ist sie häufiger
* als in den übrigen Jahreszeiten, wiewohl man sie auch oft im Sommer
* und zuweilen im Frühling sieht. Im Sommer haben wir fast alle Tage
* eine Art kleiner Lavandaja des Nachmittags; indess ist sie auch hier
* vor Sonnenaufgang und nach Sonnenuntergang am prächtigsten.
* "In Molfetta sieht man die Lavandaja mehrentheils über dem Monte Gargano ,
* einem Gebirge, welches in die See vorspringt, von Molfetta 60 ital.,
* (15 deutsche,) Meilen entfernt ist, sich von dort am äussersten Horizonte
* zwischen W.N.W. und N.N.W wie eine dunkelblaue Wolke zeigt, und aus dessen
* Ansicht, je nachdem es sichtbar oder unsichtbar ist, und die Wolken den
* Fuss oder den Gipfel desselben bedecken, oder einen grossen Hut darüber
* bilden,) die Schiffer das Wetter mit vieler Zuverlässigkeit vorhersagen.
* Beim ersten Mahle, als ich daran die Lavandaja , ohne noch von ihr
* gehört zu haben, sah, wurde ich wirklich unruhig. Das ganze Gebirge
* war in einer zitternden Bewegung ; ein Theil des Berges versank und
* liess ein grosses Thal zurück; an derselben Stelle erhob sich einige
* Minuten nachher ein neuer Berg, höher als der vorige, und neben diesem
* stiegen mehrere andere kegelförmige empor, nahmen aber sogleich die
* Gestalt grosser viereckiger Thürme an, die sich eben so in einem
* Augenblicke versenkten und grosse Thäler eröffneten. Endlich schien
* mir der ganze Berg fürchterliche Erschütterungen zu leiden. --- Ich
* habe diese Abwechselungen oft mit dem grössten Vergnugen beobachtet.
* Die wunderbarsten Figuren folgen in einem Augenblicke auf einander,
* und eine nur etwas warme Phantasie wird sich sehr leicht überreden,
* Pferde, Menschen, Schiffe, Thürme und Städte zu sehn.
* "Noch eine besondere Lavandaja zeigt sich hier, besonders wenn die
* Sonne gegen Westen steht und ein leichter Ostwind weht. Das Vorgebirge
* Gargano verändert dann mit der grössten Geschwindigkeit seine Gestalt
* auf eine unendlich mannigfaltige Weise. Es verlängert sich, zieht
* sich wieder zusammen, und scheint in viele Theile zerstückt, die das
* Ansehn von Inseln im offenen Meere haben. Zuweilen scheint ein Theil des
* Meeres viel höher zu seyn als das übrige, und das Wasser in der Ferne
* scheint von einem heftigen Sturme bewegt zu seyn, ob es sich gleich in
* vollkommner Ruhe befindet." (pp. 11-14).
* He then goes on to describe a case of looming at sunrise on 15
* Oct. 1789, "in meinem Landsitze eine halbe Meile von Molfetta," which
* brought into view several towns normally hidden. This was also seen by
* Dr. Tripaldi. "Um 9 Uhr, nachdem wir 3 Stunden beobachtet hatten, war
* alles wieder wie gewöhnlich. In Hoffnung, das Phänomen wieder zu sehn,
* wenn ich höher träte, stieg ich auf eine Terasse, die ungefähr 20 par.
* Fuss über dem Fenster liegt, und wirklich sah hier das Schauspiel noch
* in seiner ganzen Schönheit. . . . Da D. T r i p a l d i am Fenster
* geblieben war, so überzeugten wir uns, dass damals das Phänomen 40 Fuss
* über der Erde gar nicht, in 60 Fuss Höhe aber vollkommen sichtbar war."
* (p. 16)
* Giovene recognized that these were all refraction phenomena; but he
* tried to connect them with minerals in the ground. As usual, "Dünste"
* get the blame. Still, he suspects "eine . . . wellenförmige Bewegung" of
* the air is responsible for the motions.
* ANTONIO MINASI's classic (if rather exaggerated) Fata Morgana review
* This is Gilbert's translation into German of Nicholson's translation
* into English from Minasi's original Italian, with commentary by
* both Nicholson and Gilbert. . . .
* Gilbert is very hard on Minasi: "Ich entlehne diesen Aufzug aus Minasi's
* Werke über die Fata Morgana aus Nicholson's Journal of nat. philos.,
* Vol. I, p. 225. Da Minasi's Träumereien selbst bei einem so
* nüchternen und scharfsinnigen Physiker, als Nicholson, Eingang gefunden
* haben, so hielt ich es für nicht unverdienstlich, darzuthun, dass
* Minasi's Nachrichten mit so viel Einbildungen versetzt sind, dass man
* sie im Ganzen kaum für etwas mehr, als für ein Mährchen nehmen darf,
* und sie bei einem Versuche, die Fata Morgana zu erklären, lieber ganz
* bei Seite legt." [footnote attached to the title!]
* Here I credit all three as authors; none is named explicitly. Notice
* that most of pp. 24 - 30 is occupied by a long commentary by Gilbert on
* Minasi's dissertation.
* Furthermore, Gilbert refers to Reinecke's discussion of Minasi in the
* footnote on p. 26 here, as "der Verf. des Aufsatzes in den Allg. ge. Eph.
* 1800, S. 199," and again in the notes on pp.30 ("Verfasser des angeführten
* Aufsates [sic] in den geogr. Ephem. ) and 32.
* The harsh and rather dismissive treatment of Minasi here resembles
* Büsch's scornful comments on Minasi in A.G.E. Vol. 6 (1800).
* William Beauford's perceptive review, just before Wollaston's
* Probably this should be an entry in the FOG file. However, his
* perceptive remarks require its presence here, despite his curious
* explanation: "Of all the phænomena exhibited by nature in her various
* operations, there are none more curious and extraordinary than those
* represented by the reflection and refraction of light from fogs and
* vapours arising from the sea, lakes, and morasses, replete with marine
* and vegetable salts. For such vapours, by means of the said salts,
* form various polished surfaces, which reflect and refract the light of
* the sun, and even the moon, in various directions; thereby not only
* distorting but multiplying the images of objects represented to them in
* a most surprising manner; forming not only images of castles, palaces,
* and other buildings, in various styles of architecture, but the most
* beautiful landscapes, spacious woods, groves, orchards, meadows, with
* companies of men and women, with herds of cattle, walking, standing,
* lying, &c., and all painted with such an admirable mixture of light and
* shade that it is impossible to form an adequate conception of the
* picture without seeing: not any scenery represented by the
* camera obscura can be more beautiful, or more like faithful
* representations of nature."
* Nice discussion of TERMINOLOGY: "The only ones which seem at present
* to have attracted the attention of the curious, are those frequently,
* during the summer season, seen on the southern coasts of Italy, near the
* antient city of Rhegium; and even to this attention they were directed
* by the fishermen and country peasants, who in their native tongue call
* them fata morgana , or dama fata morgana . They are, however,
* frequently noticed by the English, Erse, and Irish peasants, fishermen,
* and mariners; and denominated in the languages of the two latter
* feadhreagh mairethmhe , or sea fairies, and duna feadhreagh , fairy
* castles. . . . On the eastern and western coasts of South America, even
* on the highest summit of the Andes, the fata morgana is met with.
* Also far out at sea, in the midst of the Atlantic and Pacific oceans,
* the adventurous mariner sometimes observes them; and though well known
* under the name of fog banks , yet has their appearance been so imposing
* as to illude the nicest scrutiny, and to promise refreshments to the
* fatigued and sea-worn mariner which he could not obtain. The most
* antient account of these aërial castles and islands which has been
* transmitted to us, is the representation of a beautiful island situated
* nearly in the middle of the Atlantic ocean, between the coasts of
* Ireland and Newfoundland, first observed by Danish and Irish fishermen
* about the year 900, and from that period to the commencement of the 14th
* century frequently by the Anglo-Saxon, English, and French fishermen and
* mariners.
* "But, as this island could never be approached, it was called the
* inchanted island , and supposed by the maritime inhabitants of Scotland,
* Ireland, France, and Spain, to be the country of departed spirits, and
* consequently denominated in Erse Flath Innis , or the Noble Island; in
* Irish Hy Brasil , or the Country of Spirits; by the Anglo Saxons,
* Icockane , or the Country in the Waves; and by the French and Spanish,
* who supposed it to consist of two distinct islands, Brasil and
* Assmanda ; or the Islands of Ghosts."
* He then describes the Irish mirages in agonizing detail: "The country
* seemed laid out in lawns and improvements, in which were situated three
* gentlemen's seats; the houses well defined, the windows and doors
* distinct; some of the windows appeared open, and brass knockers were
* seen on the doors." [etc., etc., at some length.]
* Then we get more factual details: ". . . none of those aërial
* exhibitions continue any length of time, and always in calm weather and
* a clear sky, if the picture is brilliant; for, though those fog banks
* often appear in dark or cloudy weather, the reflection is imperfect, and
* represents only confused images of rocks, mountains, and capes."
* Then the final, fatal admission: "For the vapour, being formed into
* different parts, the light refracted through them causes the confused
* appearance of ruins, houses, woods, lawns, &c. in the same manner as a
* board covered in an irregular manner with black and white spots mixed
* with lines, will at a certain distance resemble a landscape with woods,
* ruins, houses, trees, castles, &c., and under such imposing forms as to
* appear real representations. Of this species of the fata morgana seem
* to be those seen at Youghal in 1801 before spoken of; but in whatever
* manner the representations from vapours and fogs are formed, the weather
* must be calm and serene, otherwise the vapours will be broken and
* dispersed by the wind." (cf. Baur, 1857)
* There is a passing mention of Commodore Byron's Voyage round the World.
* Note that Beauford cites both Swinburne's Travels and Crantz's
* History of Greenland . The long s is used throughout.
* NOTE: In his letter to me of 2 Feb. 2002, Irish folklore expert
* Miceal Ross has some harsh words for Beauford's scholarship here:
* "I do not know where he gets his Irish from. I never heard a word
* called feadhreagh and if it existed the declension would be faulty and
* also the spelling. The 'e ' after dh would be impossible. . . . Duna should
* be Dúnta. It looks like the same William had no Irish and probably
* little access therefore to tradition.
* "Flath Innis [recte Flaith Inis] means the isle of princes; Hy Brasil
* or Brazil is in Irish `Í Bráth-saol' The island of eternal life."
* [Yet the criticized words appear in some 19th-Century books; cf.
* M`Farland, 1853. . . .]
* WOLLASTON picks up Monge's use of "mirage" in his Bakerian Lecture:
* He starts by refuting Monge's density discontinuity:
* "The definite reflecting surface which he [Monge] supposes to take
* place between two strata of air of different density, is by no means
* consistent with that continued ascent of rarefied air which he himself
* admits; and the explanation founded on this hypothesis will not apply
* to other cases, which may all be satisfactorily accounted for, upon the
* supposition of a gradual change of density, and successive curvature of
* the rays of light by refraction." (p.2)
* There is also a fine illustration of the SMOOTH BEND where the erect
* and inverted images meet; the figure on p. 3 is the same one reprinted
* as Tafel VII, Fig. 6 in Gilb. Ann. vol. 23, showing the bent oar. It
* is worth quoting his passage about this (pp. 3 and 4):
* "I was sitting in a boat near Chelsea, in such a position that my eye
* was elevated about half a yard from the surface of the water, and had a
* view over its surface, that probably somewhat exceeded a mile in length,
* when I remarked that the oars of several barges at a distance, that were
* then coming up with the tide, appeared bent in various degrees, according
* to their distance from me. The most distant appeared nearly in the form
* here represented; dd being my visible horizon by apparent curvature
* of the water; ab the oar itself in its inclined position; and bc
* an inverted image of the portion be . By a little attention to other
* boats, and to buildings on shore, I could discern that the appearance
* of all distant objects seen near the surface of the water was affected
* in a similar manner, but that scarcely any of them afforded images so
* perfectly distinct as the oblique line of an oar dipped in the water.
* "A person present at the time (as well as some others to whom I have
* since related the circumstance) was inclined to attribute the appearance
* to reflection from the surface of the water; but, by a moderate share
* of attention, a very evident difference may be discovered between
* the inversion occasioned by reflection, and that which is caused by
* atmospherical refraction. In cases of reflection, the angles between the
* object and image are sharp, the line of contact between them straight and
* well defined, but the lower part of the image indefinite and confused,
* by means of any slight undulation of the water. But, when the images
* are caused by refraction, the confines of the object and its inverted
* image are rounded and indistinct, and the lower edge of the image is
* terminated by a straight line at the surface of the water."
* (Similar advice is given by Bravais, 1853.)
* Brandes's first communication about refraction mentions Woltman
* "Ich hoffe Ihnen nächstens eine Reihe von Beobachtungen über
* die Refraction , denen ähnlich, die Sie von Hrn. W o l t m a n n
* kennen, übersenden zu können."
* This item is under the heading "Auszüge aus Briefen an den Herausgeber"
* Castberg's FATA MORGANA review (translated by Gilbert)
* Several very early references here: Pomponius Mela, Thomas Facellus,
* Athanasius Kircher, Pliny and Haithon. But he is mostly concerned with
* the F.M. classics: Minasi and Angelucci. There are also references to
* then-recent discussions by Gilbert, including looming and mirages.
* Castberg leans heavily on the idea that, if this were a simple mirage,
* the locals would recognize the miraged objects: they don't, so it isn't.
* He makes the good point that the cities are too far apart (6500 toises):
* at this distance, one would be hard pressed to make out individual
* buildings, let alone individual figures, trees, sheep, etc.
* [This matter of DISTANCE is often overlooked in fantastic reports.]
* Furthermore, if it were a mirage of Messina seen from Reggio, then the
* reverse should be true; but (he says) there are no reports of the
* Morgana being seen from Sicily.
* He concludes that it is the shadows of the city cast on mists!
* Brandes comments on atmospheric optics, including FATA MORGANA
* The Fata Morgana is discussed on p. 367, where he comments on Castberg's
* report in Ann. 17, 183. There is an amusing crack: "Die Bilder sind
* gewöhnlich so verzerrt, und der Gegenstand selbst erscheint unter so
* veränderter Gestalt, dass man leicht mit Hülfe einer italiänischen
* Phantasie Säulengänge, Wasserleitungen, u. s. w., in diesen
* Erscheinungen finden kann."
* See also the Brandes papers from vols. 17 & 18 in "Terrestrial Refr."
* [from a letter dated 2ten Febr. 1805]
* Brandes reports his progress to Gilbert
* There is some interesting background here: he explains how he was led
* by Pictet's observations of the diurnal cycle of temperature gradients
* at different heights, which showed the same pattern he had already seen
* in his own observations of variable terrestrial refraction, to make such
* temperature measurements himself.
* [from a letter dated 16ten Mai 1805]
* Biot's astronomy textbook (1805)
* Astronomical refraction is discussed on pp. 36-38; mirages on p. 40
* In §43 (p. 39), he refers to Maraldi's work on terrestrial refraction.
* The description of mirages in lower Egypt is taken almost verbatim from
* Monge's text, though edited down slightly: "Monge a expliqué ce phénomène
* d'apres les lois de l'optique, dans le premier volume de la Décade
* Egyptienne." (p. 41)
* The Plates that follow p. 330 indicate by simple diagrams the effect of
* astronomical refraction; but there are no mirage pictures. [Those appear
* in the 2nd edition (1810).]
* The first volume bears a dedication to Laplace (cf. Biot's anecdote!)
* Often, the two volumes of this work are bound together.
* The 1st volume is available at Google Books:
* https://books.googleusercontent.com/books/content?req=AKW5QaeMiMxzOhQ-yyV3yUE1sfwPMeOJxlGy0n44v6jKTIzjiWVTQN0sgG8bQy_wREdv7JVSaNvq7NZ1oUAq3S4Z2cO1OXn8Le43gtuy6IAdsWATwEFjMv4Oxh6cr0gLh7stxiARR3OipKqTX09mp5R4oCPd_AF9VLLFLlLlx62bXX7KfipBo5kKxM0KJVCwGTMCVKZ15gTEb6jJZ-MOn_2N3rS4RjqY5EPzBDVPxbthL289HJiq3H2hw0-b9LisxfXBMP9-rVUesYPs1gGwBcZB1QWbYJFac5kuAnDsN5iEzF4GlC3XhxQ
* Friedrich Christian Kries points out the lack of explanation in the
* reports of Vince and Wollaston, and tries to explain away Wollaston's
* experimental results as an artifact due to surface tension at the
* edge of the glass. However, his explanation of the 2-image superior
* mirage is exactly the same as Wegener's, apart from using (here) a flat
* Earth. Because of omitting this vital detail, he fails to understand
* how a 3rd, upright, image can be formed. So he introduces the crazy
* notion of a perfect reflection in the sea , which he supposes is
* inverted to form the uppermost, erect, image.
* But there is a prophetic phrase in which he foresees the actual
* complexity of thermal inversions:
* "Und da Luftspiegelung oberwärts mit starken Hebung verbunden zu
* seyn pflegt, so ist es nicht unwahrscheinlich, dass alsdann mehrere
* Luftschichten von verschiedener Dichtigkeit über einander liegen."
* According to Pogg., Kries was born in "Thorn, Westpreuss." -- the
* home town of Copernicus.
* Brandes comments at length on earlier reports, and announces his
* forthcoming ("um Michaelis") monograph (1807) [below].
* Several nice quotes here. On p. 383, good advice for astronomers:
* EARLIEST MENTION of NOCTURNAL INVERSIONS ???
* "Da wohl ohne Ausnahme über einer Erdfläche die Luft Nachts, dicht
* an der Erde kälter ist, als in der Höhe, . . . ." He notes that, with
* strong looming, the sea often appears concave rather than convex (p.385).
* [Note observation of CONCAVE surface.]
* [The concave appearance is also described by Forel (1895), p. 541.]
* Remarking on the stories Busch was told by the dike-workers, he says:
* "Ueberhaupt hat der gemeine Mann selten die Gabe, eine Erscheinung so zu
* beschreiben, dass der Physiker die Erzählung gebrauchen kann." (p. 386)
* On the next page is another suggestion for the origins of strange
* reports: "Ich sah neulich auch früh Morgens von hier aus das weiss
* übertünchte Schloss zu Varel und einige andere Gegenstände mit blossen
* Augen so auffallend hell, dass ich es wohl für näher hätte halten
* können; von besonderer starker Refraction war aber nichts zu bemerken,
* sondern ich konnte keinen anderen Grund finden, als dass diese
* Gegenstände hell von der Sonne beschienen wurden und die übrige Gegend
* im Schatten von Wolken lag. Grösser erschienen die Gegenstände auch
* nicht, aber bei so starker Beleuchtung kann ein scharfes Auge einzelne
* Theile der entfernten Gegenstände erkennen, und dies mochte die
* Täuschung verursachen, dass man sie für grösser hielt."
* The Figures show a distorted sunset, probably with mock mirage.
* He wonders if Heemskerk's observations on Nova Zembla were not this?
* [From letters dated 18ten April & 15ten Mai 1806.]
* Note that his drawing of a mock mirage in Tafel VII, Fig. 3 & 4,
* is probably the EARLIEST such sunset recorded pictorially.
* Wollaston's 1803 article translated by Gilbert.
* His Fig.6 is remarkable for showing the smooth bend in a miraged oar
* extending from a barge to the water. This vertical magnification
* is what makes the inferior-mirage flash visible to the naked eye.
* DANGOS reports his observation of early OMEGA (and looming of Etna)
* "Ayant lu depuis peu, dans la connoissance des temps de l'an 12, une
* observation curieuse sur les réfractions terrestres, faite par un
* savant physicien anglois, j'ai pensé que l'Institut national verroit
* avec plaisir les détails d'un phénomène à peu près semblable, qui se
* montra à Malte en 1784, et dont tous les habitans de l'île furent les
* témoins.
* "Le 20 mars vers 1 heure de l'après-midi, je fus instruit par des
* grands cris qui retentissoient dans les rues, qu'une île venoit de
* s'élever dans le canal de Malte, et j'aperçus bientôt, de dessus les
* terrasses de l'observatoire, une terre très-blanche, entourée d'eau,
* et dont la forme étoit celle à peu près d'un cône droit
* irrégulièrement tronqué. Des marins et des pêcheurs étoient déja
* partis pour aller reconnoître cette île et pour en prendre possession.
* "La figure de cette terre, sa blancheur et surtout sa position, qui
* se trouvoit exactement dans la direction de la mire que j'avois tracée
* depuis long-temps vers le mont Etna, me firent reconnoître bien vîte
* que cette terre n'étoit autre chose que le sommet toujours neigé de ce
* mont élevé de 3326 mètres . . . ." [The modern figure is 3323 m.]
* ". . . cette apparence extraordinaire dura environ 30 minutes depuis
* l'instant où j'en eus connoissance. . . . La mer étoit calme, le vent
* nord-est foible, le thermomètre à 14° 4'; . . . le temps étoit
* humide, et il avoit régné un brouillard épais toute la matinée,
* ainsi que la veille."
* From his further description of a repeat of this performance on 17
* April 1785 at 6:10 a.m., it appears that the island had been hidden by a
* superior mirage that reflected the sea: ". . . l'horizon de la mer qui
* l'entouroit étoit extrêmement net. . . . L'île . . . survint un instant
* de confusion, et lorsque je la cherchois dans les airs, je la vis, avec
* étonnement, assise à sa place. Tout le mont et les côtes de Sicile,
* qui avoient été invisibles, se montrèrent bientôt en entier, et
* furent visibles le reste du jour." On this occasion, he measured the
* "depression" and found it 15' 17'', "ce qui donneroit pour sa distance
* apparente de l'observatoire, à peu près 18000 mètres . . . ."
* [The actual distance is about 130 km.]
* He notes this cannot be a simple reflection, "comme on le prétendit
* dans les journaux d'Italie : car alors l'image auroit dûe être
* renversée, et elle étoit droite . . . ." So I suppose it is the isolated
* 3rd image of a 3-image mirage.
*
* Now comes the OMEGA report:
* "Je finis en rappelant un phénomène assez curieux qui tient à
* l'objet de ce mémoire, phénomène bien connu des marins, des
* astronomes qui ne sont pas fort éloignés de la mer, que j'ai vu assez
* souvent à Malte et surtout à l'observatoire de Rouen.
* "Le soleil prend quelquefois, vers son lever, une forme un peu
* allongée qui se rétrécit tout-à-coup dans sa partie inférieure, et
* qui est terminée par le bas, par une ligne droit, de sorte qu'il
* ressemble à une urne sur son piédestal." (Jules Verne, did you read
* this?)
* "La cause de ce fait est bien simple, d'après la théorie de
* M. Monge sur le mirage . . . ."
*
* ``Lu le 27 prairial an 10'' which works out to June 15, 1803 if my
* arithmetic is correct.
*
* NOTE: I have filed the 1814 German translation in the Colton file.
* It lacks the last paragraph connecting the Omega display with Monge's
* mirage. (Cf. Jacques Cassini's Omega sunrise, nearly a century earlier!)
*
* This is indexed under different titles; I have not seen the actual
* title page of the volume. The Royal Society Catalogue says it was
* ``Mémoires présentés à l'Institut des Sciences, Lettres, et Arts par
* divers Savans, et lus dans ses Assemblées : Sciences Mathématiques et
* Physiques'' for Vols. I and II (1806-1811). The later title, according
* to the same source, was ``Mémoires présentés par divers Savans à
* l'Academie [Royale] des Sciences de l'Institut de France; ou Collection
* des Mémoires des Savans Étrangers'' from 1827 on. However, the
* page headers read ``Mémoires présentés a la classe des sciences
* mathém. et physique'' and the footer has ``Sav. Étrangers. 1. T. 1.''
* The ILL people got a copy by asking the Bibliothèque de l'Institut for
* ``Memoires de l'Institut national de France.'' Take your pick.
* THOMAS YOUNG's remarks on refraction, in his "Lectures" book
* A good source of early references on refraction & mirages.
* EARLY treatment of the RN = const. model: Section 461 (cited in his
* paper below) is pp. 80-81. [Cf. Kummer!]
* On p. 81, he seems to lose the factor of 2 in terrestrial refraction,
* saying ". . . the terrestrial refraction, instead of being 1/7 of the arc
* intervening between two places, is seldom more than 1/10."
* Available at https://archive.org/details/lecturescourseof02younrich
* and http://www3.nd.edu/~powers/ame.20231/young1807.pdf
* THOMAS YOUNG's remarks on mirage theory
* Young comments on the inadequacy of Wollaston's demonstration.
* He proposes a model very similar to that of August Schmidt (1878)!
* "If the variable medium be only thick enough to admit the passage of
* rays below [the height where the conjugate point turns around], there will
* be no direct image, but an inverted one only. . . . the case being nearly
* similar to a very oblique internal reflection." (p. 154) -- cf. Wegener!
* "The points K and ε may be considered as conjugate foci, with
* respect to the refraction of the variable medium."
* He considers DUCTING and CRITICAL REFRACTION: the assumed temperature
* gradient of 1 degree (F?) per foot of height produces a ray curvature of
* 1 second of arc in 16 feet of path length; "The curvature of the earth's
* surface becomes a second in 102 feet; consequently . . . a change of
* temperature of a degree in 6 or 7 feet, would be sufficient to produce
* a refraction equivalent to the apparent depression of a distant object
* arising from this cause, and to elevate the coasts of a wide channel,
* so as to make them visible to each other. This result may also be more
* simply obtained from Simpson's investigations respecting atmospheric
* refraction, the refractive density being inversely proportional to the
* distance from the centre of the earth, when the temperature varies 1°
* in 6 or 7 feet; for, as Dr. Young observes in his extensive system of
* natural philosophy lately published, Vol. II, Art. 461, `If the refractive
* density of a medium vary as a given power of the distance from a certain
* central point, the angular deviation of a ray of light will be, to the
* angle described round the centre, as the exponent of the power to unity.'"
* (p. 155) [cf. Kummer (1860)]
* Then there is a Postscript (pp. 155-156) that continues the discussion,
* finding the image position (cf. Gergonne, Nölke, etc.).
* Note that Plate V faces p. 153, the title-page of the article.
* This is usually known as "Nicholson's Journal"; dated July.
* Heinrich Wilhelm BRANDES uses temperature gradient info
*
* Here is the first paragraph (p. 3):
* "Obgleich es eine lange bekannte Wahrheit ist, daß nur in sehr
* wenigen Fällen die Lichtstralen von einem entfernten Gegenstande auf
* der Erde in gerader Linie zu unserm Auge kommen, und daß wir daher
* selten oder vielleicht niemals die Gegenstände in derjenigen Richtung
* sehen, in welcher wir sie sehen würden, wenn der Lichtstral durch einen
* gänzlich leeren Raum oder durch ein völlig gleichartiges Medium zu uns
* gelangte, so ist doch die Anzahl der Beobachtungen über diese Brechung
* des Lichtstrals in den untern Luftschichten noch immer nicht so groß
* als es bei einem so interessanten Gegenstande zu wünschen wäre, und
* noch immer fehlt es uns an sichern Regeln, um die wahre Höhe eines
* Gegenstandes auf der Erde aus seiner scheinbaren Höhe zu bestimmen."
*
* ". . . die großen Aenderungen, denen die scheinbare Höhe eines
* bestimmten Gegenstandes, den man aus einerlei Standpunkt betrachtet . . . "
* "Schon mehrere Beobachter hatten zwar die ungleiche Erwärmung der Luft
* in verschiedenen Höhen, als einen vorzüglichen Grund mancher hier
* vorkommende Phänomene angegeben; aber so viel mir bekannt ist, hatte
* noch keiner durch Beobachtungen gezeigt, daß die Aenderungen der Refraktion
* ganz genau mit der Aenderung der Unterschiede der in verschiedenen
* Höhen statt findenden Wärme übereinstimmen. Dieses darzuthun,
* waren meine ferneren Beobachtungen bestimmt, und wenn die ersten
* Beobachtungen nur dahin leiten konnten, empirische Regeln für die
* Bestimmung der gleichzeitigen Aenderungen der scheinbaren Höhe
* verschiedener Gegenstände anzugeben, so müssen die leztern,
* wofern sie ihren Zweck erreicht haben, uns in der theoretischen Bestimmung
* der Refraktion einen Schritt weiter bringen." [p. 5]
*
* The INFERIOR MIRAGE discussion begins on p. 111 (section 61). On p. 114
* he mentions the reduced size of the inverted image; if this were due to
* simple reflection, ". . . wo sollte hier die polierte Fläche sein, auf
* welcher sich der Gegenstand abspiegelte? Vielmehr ist das Phänomen aus
* einer Refraction der Lichtstralen zu erklären . . . ." And in §65:
* "Je mehr die Erdfläche erwärmt ist in Vergleichung der höheren
* Luft-Schichten, desto stärker ist die Spiegelung, . . . ." -- and he gives
* several examples from his own measurements. A ray-traced example is
* treated in §66 (p. 115) and Fig. 10. He trips over the horizontal-ray
* paradox, but talks himself out of it by asserting that it is the
* spherical curvature of the refracting surfaces that allows the ray
* to find its way back up from the perigee point!
* §67 (p. 116) discusses the ray vertices: ". . . und deswegen erscheint das
* untere Bild umgekehrt." (p. 117) Then in §68 he has a nice argument to
* determine the point where the erect and inverted images join, by
* interchanging object and observer.
* §68b then discusses the location of the apparent horizon: ". . . die
* scheinbare Tiefe des Horizonts ist also um etwas sehr erhebliches
* grösser, als sie bei gradlinigtem Fortgange der Lichtstralen sein
* sollte. . . . so is offenbar, dass der sichtbare Horizont sich mit der
* Erniedrigung des Auges sehr merklich verkleinern muss, welches auch
* wirklich sehr auffallend der Fall ist, wenn man auch die Höhe des Auges
* nur wenig ändert." (p. 118)
*
* The SUPERIOR MIRAGE discussion begins on p. 121 (section 72).
*
* EARLY MIRAGE OF SUN (cf. the similar publication in Gilberts in 1806.)
* (section 78, p.126): "Eine Erscheinung muß ich noch erwähnen, die
* ebenfalls hier gehört. Am 8. April 1806 nämlich erschien die Sonne beim
* Untergange in einer solchen Gestalt, wie Fig. 18. zeigt. Hier ist offenbar
* a c b das aufrechte, d c e das umgekehrte und d f e das zweite
* aufrechte Bild. Ich hatte damals kein Fernrohr zur Hand, aber am folgenden
* Tage, wo die heitre Witterung mit Ostwind fortdauerte, zeigte sich beim
* Untergange der Sonne etwas ähnliches, obgleich die Spiegelung
* schwächer war, und diese Erscheinung habe ich mit dem Fernrohr beobachtet.
* Die Sonne erschien nämlich wie Fig. 19. und als sie tiefer sank,
* trente sich das Stück oberhalb des Einschnitts ab, schwebte noch
* abgesondert einen Augenblick und verschwand dann. Etwas später trente
* sich noch ein zweiter solcher Streifen. -- Die Sonne erschien zitternd und
* daher schlecht begrenzt, indeß war diese Erscheinung sehr deutlich. --
* Tages vorher waren Nachmittags auch einige südlich liegende
* Gegenstände oberwärts gespiegelt.
* "Diese Spiegelung der Sonne könte, dünkt mich, gar nicht statt
* finden, wenn die Schichte, worin die starke Brechung erfolgte, sich sehr
* weit, z.B. über den ganzen Gesichtskreis, erstreckt hätte.
* Stellt nämlich (fig. 20.) d c die oberfläche der Erde, b die
* Gegend vor, wo der Scheitel des Strals [sic] lag, so würde, wenn in a
* eben so starke Brechung, als in b statt finde, keine Vervielfachung des
* Bildes möglich gewesen sein."
*
* Google Books has the text, but it is made useless by their usual failure
* to open the gatefolds of tables and figures.
* Further observations by Brandes, with an appeal for support by Gilbert
* The letter from Brandes to Gilbert actually begins on p. 135; the
* first 2 pages are Gilbert's comments, citing the earlier works.
* Most of Brandes's letter is a summary of the high points of his book.
* However, he has a few comments at the end about what needs to be done,
* which would be good advice to mirage observers generally (pp. 148 ff.).
* He notes the TRIPLE IMAGE often associated with superior mirages:
* "Eine genaue Betrachtung der Umstände, welche diese Spiegelung fast
* unstreitig bewirken, zeigt, dass man eigentlich dann immer drei
* vollständige Bilder und in dem höchsten alle Mahl die Spitzen der
* Gegenstände sehen sollte . . . ." (p. 146) as well as its association
* with the Fata Morgana.
* There is also a nice comment about the Fata Morgana : "Sie scheint
* mir eine veränderliche Spiegelung zu seyn, die in einem Augenblicke
* vielleicht in demselben Punkte des Horizonts einen Gegenstand zeigt, der
* Meilen weit hinter dem liegt, welchen man im nächst vorhergehenden
* Augenblicke sah. . . . Freilich könnte auch dann noch, wegen der
* Mannigfaltigkeit der Gegenstände, die hinter einander in einerlei
* Richtung liegen, sich mancherlei zeigen; aber gewiss würde man bei
* solchen Beobachtungen doch eher zu einer Erklärung gelangen, als durch
* die Beschreibung von Feenschlössern und andern Herrlichkeiten, die
* gewiss nur die Fantasie sah, und nicht das Auge." [p. 147]
* And (p. 151): "Allem, was ich bis jetzt von Beschreibung dieser
* Phänomene kenne, scheint ganz der philosophische Geist zu fehlen,
* welcher nötig ist, um gerade das Rechte zu treffen, und aus dem Chaos
* von zerstreuenden Nebendingen nur den Hauptpunkt hervor zu heben."
* He also notes the bad seeing that accompanies the inferior mirage:
* ". . . mit dieser Spiegelung . . . fast ohne Ausnahme ein heftiges Zittern
* der Gegenstände verbunden ist . . . ." [p. 150]
* Biot and Arago's expedition recounted
* The "Notice sur les Opérations d'Espagne et de France" (pp. 1-30
* here), "Lue à la séance publique de la classe des Sciences de l'Institut,
* le 2 janvier 1810" is the account quoted in the 1821 book by Biot & Arago;
* see below (at 1821) for excerpts.
* Now available at
* http://www.academie-sciences.fr/membres/in_memoriam/Biot/Biot_pdf/Notice_EsFr_1810.pdf
* but they don't give the exact citation; probably this appeared in one of
* the Academie's serial publications. . . .
* This was reprinted in Biot's Mélanges Scientifiques et Littéraires
* (M. Levy, Paris, 1810), pp. 47 - 68.
* Thanks to Luc Dettwiller for pointing out the availability of this item!
* Abstract of the 8 Aug. talk by J. B. BIOT on refraction phenomena
* A marginal note says:
*
* Instit. Nat.
* 8 Août 1808.
*
* and the signature footers say "Tome I. N°. 15, 2e. Année." The title
* page of the volume is dated 1807, and a few Roman-numeraled pages at
* its front explain the interruption in publication of the Society's
* Bulletin in 1805. On p. vi is the editorial staff of the revived
* Bulletin; Mathematics is handled by Poisson ("P.") The first number
* of this volume is dated Oct. 1807.
* Here, Monge, Wollaston, and Humboldt are mentioned, and their
* explanations are summarized. Poisson says:
* "On ne peut donc pas douter que cette explication ne donne la vraie
* cause du Mirage. Mais, pour ia mettre dans tout son jour, il étoit bon
* de déduire de l'analyse mathématique, les diverses circonstances que
* peut présenter ce phénomène, et qui sont relatives à l'élévation de
* l'observateur au-dessus du sol, à sa distance aux objets mirés, et à
* la rapidité du décroissement de la température. C'est ce que M. Biot
* s'est proposé de faire dans le mémoire que nous annonçons. On trouve
* aussi dans ce mémoire, l'explication de plusieurs phénomènes qui ont
* un rapport plus on moins éloigné avec le Mirage. Le plus remarquable de
* ces phénomènes est la double image du soleil à l'horison, observée par
* Le Gentil à Pondichéri et sur les côtes de Normandie. M. Biot attribue
* cette parélie à la même cause qui produit le Mirage. En général,
* M. Biot a rassemblé dans son mémoire les nombreuses observations de
* Mirage ou de phénomènes analogues, qui ont été faites jusqu'ici,
* afin qu'on puisse en comparer les résultats à ceux du calcul."
* This is available at the BHL website:
* https://www.biodiversitylibrary.org/page/31774998#page/278/mode/1up
* Full title of publication is:
* Nouveau Bulletin des Sciences, par ls Société Philomatique. Paris.
* (A variety of local scientific societies called themselves "Philomathic"
* in this period; so it's necessary to specify which one by location.
* The Roy. Soc. Cat. calls this "Paris, Soc. Philom. Bull." The BHL
* calls it "Nouv. Bull. Sci. Soc. Philom. Paris".
* Note the spelling "horison" with an "s" rather than a "z", in both the
* title and the text.
* The abstract is signed with the initial "P." = Poisson.
* Italian report on Biot's mirage memoir: first use of "miraggio" ?
* The title page of the volume says:
*
* GIORNALE
*
* DI FISICA, CHIMICA
* E STORIA NATURALE
*
* ossia <-- (in small caps)
*
* Raccolta di Memorie sulle Scienze, Arti, <-- (in flowery script)
* e Manufatture ad esse relative
*
* DI L. BRUGNATELLI
*
* [followed by a long paragraph of his degrees, awards, memberships in
* numerous foreign learned societies.]
*
* TOMO II
*
* CON TAVOLE IN RAME
*
*
* PAVIA nella Tipografia Capelli 1809.
*
* -----------------------------------------
* Page 3 is headed "PRIMO BIMESTRE 1809"
* -----------------------------------------
* Successive pages are headed "Giornale" and "di Fisica, Chimica, ec."
*
* This item beginning in p. 63 is headed:
*
* ESTRATTO DI UNA MEMORIA
*
* Sopra le refrazioni straordinarie che si osservano
* vicinissime all'orizzonte; del Sig. Biot
*
* (Instit. Naz. di Francia 8. Agosto 1808. l. c.)
*
* The footnote about Pliny on p.65 is signed "L'Edit." so I think I am
* safe in attributing it to Luigi Valentino Brugnatelli (as does the Royal
* Society Catalogue), Considering the timing and the dates, this must be
* based on the Philom. Soc. Bull. abstract; and in fact this is just a
* translation into Italian of that abstract.
* This is available at:
* https://www.google.com/books/edition/Giornale_di_Fisica_Chimica_e_storia_natu/ObVUAAAAcAAJ?hl=en&gbpv=1&dq=miraggio&pg=PA65&printsec=frontcover
*
* The first full version of Biot's monograph; read 8 Aug. 1808
* The Mémoires are for the year 1809; but the publication date is Aug. 1810,
* and observations made in 1809 are discussed in several places. Clearly,
* lots of material was added after 8 Aug. 1808.
* The first 98 pages of this volume contain the history of the Institute.
* (The "Histoire" and the "Mémoires" are bound together as one volume here,
* each beginning with p. 1, just like those of the Académie des Sciences.)
* After this "Histoire" comes the table of contents for both it and the
* Mémoires that follow.
* The edition scanned by Google has "1809." in its signature footers.
* The Google scan is available at HathiTrust:
* https://babel.hathitrust.org/cgi/pt?id=ucm.532436086x&view=1up&seq=9
* -- but it completely lacks the figures!
* Its table of contents on the unnumbered page after p. 98 gives the
* title as "Recherches sur les réfractions extraordinaires qui s'observent
* très-près de l'horizon", as does p. 1. Notice that the odd-numbered
* pages in both versions have the "très-près" in their headers.
* This seems to be the version that is often cited as 1809.
* Both the Readex and the stand-alone version of the mirage monograph have
* the same page numbers, and seem to be printed from the same type, except
* for some minor changes from the Google version, such as the title,
* and the end of the third line of the body text, which ends in a comma
* in the Google scan but a semicolon in the Readex/monograph version.
* The last line of text on the first page of the monograph appears at the
* top of p.2 of the edition scanned by Google. Yet the two versions must
* be printed from the same type: look at the pale e-acutes in the word
* "détachés" in line 9 of the Google scan (line 8 of the monograph) on
* page 2. (There are other pale é types in the text; evidently this glyph
* was cast separately and shrank a little more on cooling than the main
* font.)
* On p. 11, the bottom line of the monograph version appears at the top
* line of p. 12 in the Google scan. The bottom two lines on p. 12 of the
* monograph are at the top of p. 13 in the Google scan. After this there
* is a steady creep of text, with the monograph generally having one more
* line per page than the Google version. But at p. 15, the monograph
* absorbs the accumulated space by adding a 4-line footnote about Arago.
* The two versions then remain in step until Biot's text ends on p. 266.
* That page says "FIN" in the monograph; but the Mémoires continue with
* several more mathematical papers by Lagrange, Laplace, et al.
* The signatures are all marked "1809" in the footer at the first
* page of each in this Mémoire; but that date was removed from most of
* the signature labels in the monograph (see, e.g., p.201 which begins
* signature 26, or p.193 which begins sig. 25.)
* BIOT's MIRAGE MONOGRAPH
* This is the stand-alone reprint of the monograph.
* It contains BIOT + ARAGO's multiple-image red/green observation:
* "Bientôt nous ne vîmes pas seulement deux lumières, mais trois,
* quatre ou davantage. Elles se formoient et disparoissoient ensuite sans
* que le nombre de celles qui paroissoient ensemble eût rien de
* déterminé. . . . Cette formation successive a beaucoup d'analogie avec un
* autre phénomène que nous avons observé plusiers fois dans l'autres
* stations. On voyoit le point lumineux s'allonger comme une petite colonne
* de feu sous le fil vertical de la lunette, et s'étendre ainsi jusqu'à une
* certaine longueur, après quoi la colonne se rompoit tout à coup et
* formoit deux images dont le plus basse étoit sensiblement rouge, et la
* supérieure sensiblement verte; ou bien elle se concentroit de nouveau sur
* elle-même; et redevendroit un point lumineux unique, de dimension
* insensible, comme auparavant. . . . " (p.15 -- his experiments with Arago)
* See their 1821 report for more details!
* [cf. M.O. 24, 13 (1954)]
*
* This is a remarkable work: it is not only the first theoretical
* monograph on mirages, it explores many important ideas later forgotten
* and rediscovered, such as the effect of uneven ground in truncating the
* inverted image of the inferior mirage (pp. 28-33), based on Wollaston's
* (1800) measurements on a sandy road -- even including a warning about
* radiation-induced errors in air thermometry; the relation between
* the locus of the minima in the ray-paths and the occurrence of erect
* or inverted images (pp. 41 - 63; cf. Tait, 1883); the divergence of
* rays above the horizon, and hence the need for the minimum to occur
* between observer and object if a mirage is to occur (p. 65; cf. Meyer,
* White, Fraser, et al.); an observation of conjugate inferior mirages
* over uneven ground (p.84); the importance of the Earth's curvature, and
* caustic curves (pp. 151 ff.); the role of temperature in determining
* the dip of the horizon; the possibility of ducting (p. 196), and hence
* of negative dip and a false horizon (p. 203); etc. -- and all supported
* by quantitative measurements!
* The circulating ray is on p. 154. Measurements in thermal inversions
* begin on p. 163; negative dip is discussed on pp. 167 ff.
* MULTIPLE HORIZONS are mentioned on p. 265.
* August Schmidt's (1878) comments are appropriate.
* [cf. the German treatment by Brandes, 1814.]
* A "Table des Matières" follows p. 266. It contains a one-paragraph
* abstract of each major section of this long paper. The figures are
* immediately after this Table.
*
* This is occasionally cited as:
* Recherches sur les réfractions extraordinaires qui s'observent
* très-près de l'horizon, avec 9 planches; lu le 8 août 1808
* (Mémoires de l'Institut national des sciences et arts 10, pp.1-266)
* as that title (from "sur" on) appears on the first page of the text.
* That was the original title published in the Mémoires, and is repeated
* here in addition to the slightly changed wording on this volume.
* The title page gives the date of publication as 1810; but a few
* individual signatures bear the date 1809: see pp. 129 and 169.
* P. 169 discusses observations made in Dec., 1808, and p. 168 shows dip
* measurements of 6 Feb. 1809. Data measured on 8 March 1809 are on p. 31
* and 82. The last line in the table on p.32 is a Dunkirk observation on
* 23 March, 1809.
*
* Note that the drawings are by Claude Louis Mathieu (cf. Delambre, 1827)
*
* Google Books has finally made available a PDF of the whole book,
* INCLUDING Mathieu's drawings! Here's the URL:
*
* https://books.googleusercontent.com/books/content?req=AKW5Qaf5mZ7iXOyoE33ib1IUaF5cGMjYL82QdYt45kk1Al3V3dK_QSJg3RrzkyZqakad4i2v6I6zAUALrPoPI0aGCBImDkNAksaI5yfYJA33Z_UTN5aBdH1yoPm3B2eEIp_nilM_SninhFW4mFe0NEVhR5VLkAVJv9eGnDMAbfUraiZ6s1YJ_X-4JiSQKc4nHKX1RdnWzkxG3DI0xC06Ksl_o1nGnbcS57hmgrSAZPkS7bRDnl2fP3zocHpjWIyFS-m4zYpi4OBEK6JGIMKenze0VjYbHHaw3gnM_nzRUSrGeiPK9Y-Kig8
*
* Jean Baptiste Biot
* Some of the same figures appear in Biot's revised (1810) textbook:
* The miraged man is (Fig. 41); the distorted sunsets (42 & 43) are in Pl.9
* ORIGIN of the term "MIRAGE" (cf. Le Gentil, 1789!):
* After describing the ordinary inferior mirage over hot sand, such as was
* seen by the French army in Lower Egypt, he says: "On observe
* à-peu-près la même chose à la mer dans des tems très-calmes. Un
* navire, vu dans le lointain et à l'horison, offre quelquefois deux
* images, l'une directe, l'autre renversée; celle-ci absolument pareille à
* l'autre, souvent égale en intensité, en un mot parfaitement semblable à
* l'effet de la réflexion dans un miroir. De là est venu le nom de
* mirage que les marins ont donné à ce phénomène." (p.229)
* The first volume bears a dedication to Laplace (cf. Biot's anecdote!)
*
* Sergey Kivalov points out that in the second volume of this 3-volume
* work, on pp. 558-560, Biot calculates the flattening of the full Moon
* at the horizon; this establishes a long-standing interest in this topic
* that helps explain his discovery of the magnification theorem in 1836.
* [NOTE: we have this book in our Special Collections; when I went to look
* at those pages, I found them uncut. I was the first person ever to have
* read that passage in our copy, in nearly 200 years!]
* Unfortunately, the treatment here is oversimplified: he supposes the
* Moon so small that its image is symmetrical, and (worse) repeats Kepler's
* error of supposing the difference in refraction of the upper and lower
* limbs to correspond to the difference in altitudes of the true (rather
* than diminished) vertical diameter. Having neglected an appreciable
* second-order effect, he then evaluates the effect of refraction on
* the horizontal diameter, which he finds diminished by about 3 parts
* in ten thousand.
* The publication date of the second volume is 1811.
* A very poor copy is available from Gallica. Google Books also.
* The HathiTrust website has the 3rd edition -- but only the Google scan,
* so no plates. There, the discussion of the Moon's diameter is in Vol. 3,
* pp. 19 ff., published in 1845.
* The German treatment of Biot's monograph, by Brandes
* In the first 2 pages, Brandes explains why and how he has abridged this
* partial translation.
* This is only the first of two installments. As usual in Gilberts Ann.,
* the notes are as valuable as the text.
* On p. 245, commenting on Biot & Arago's observation of red/green
* dispersion of the signal light (p. 15 of Biot's book), Brandes remarks
* on "die prismatischen Farben," and cites Herschel's 1785 double-star
* catalog, p. 52 [an error: really p. 83]. His translated quotation
* attributed to W.H. is very much abbreviated, however.
* On p. 257 [Biot p. 26] appears the "magic number" of 1° 23'.
* On p. 275 [Biot p. 65] is the discussion of the minimum of the
* trajectory. Biot says the rays must be horizontal to give a mirage
* -- this is the later mis-named "Fraser's theorem". Brandes explains
* that the order of inclination of the rays at the eye is also their order
* in any layer, in the branch above the horizontal. And immediately
* afterward is Tait's belated rediscovery about the ordering of the
* minima and the nature of the image (Biot p. 66). This is discussed in
* detail later [p. 279 = Biot p. 72], after the locus of the minima is
* discussed [Brandes p. 278; Biot p. 71].
* NOTE: "Breslau" is now Wrocłow, Poland.
* The German treatment of Biot's monograph, by Brandes -- part 2
* Rev. Edward Polehampton's review of natural phenomena
* There is a fuller summary of Minasi's work than one usually finds.
* Mirages begin on p. 504; see pp. 509-514 for the section covering the
* Fata Morgana.
* "Fellow of King's College, Cambridge" says the title page.
* So this is the Edward P. who was rector of Greenford, Middlesex (1822-30).
* He was born in 1776 and died in 1830.
* This is "Vol. IV" of "six volumes".
* Evidently this is the source for Thomas Milner's similar work (1846+).
* Available on Google Books
* MANY OLD REFERENCES and some current observations (MIRAGE HISTORY)
* Cites Quintus Curtius Rufus, as well as many references to mirages
* ("Sarab") in the Koran and other Arab writings
* (Johann Friedrich von Erdmann, according to Roy.Soc. index)
* Available at:
* http://books.google.com/books?vid=OCLC05854993&id=-QUAAAAAMAAJ
* William Scoresby's "Arctic Regions" book
* The mirages are described in Sect. V, on pp. 383-392:
* "Under certain circumstances, all objects seen on the horizon, seem
* to be lifted above it a distance of 2 to 4, or more minutes of altitude,
* or so far extended in height above their natural dimensions. Ice, land,
* ships, boats, and other objects, when thus enlarged and elevated, are
* said to loom . The lower parts of looming objects, are sometimes
* connected with the sensible horizon, by an apparent fibrous or columnar
* extension of their parts, which columns are always perpendicular to the
* horizon : at other times, they appear to be quite lifted into the air,
* a void space being seen between them and the horizon." (pp. 384-385)
* A typical Fata Morgana display is well described on pp. 385-386, with
* "lofty spires, towers and battlements," converted in a few minutes into
* "a vast arch, or romantic bridge." "A mass of ice on the horizon,
* appeared of the height of a cliff, and the prismatic structure of its
* front, suggested the idea of basaltic columns. It may be remarked,
* that these phenomena took place on a clear evening, after an uncommonly
* warm afternoon." So, a textbook case; July 16, 1814.
* On the next page, another example of "variegated basaltic columns" was
* see on the coast of Spitzbergen, in June. An iceberg became "a
* prodigious cliff of alabaster pillars." Likewise, on May 13, he saw
* "a dense appearance in the atmosphere," which "advanced with the wind
* toward the N.W." The horizon under this apparent density "was
* considerably elevated; . . . a separation of seven minutes extent of the
* altitude, showed the division of the true and refracted horizons." The
* refracted horizon "had the appearance of a line drawn nearly parallel to
* the true horizon, distant from it 7 minutes, with an open space between.
* Two ships lying beset about fourteen miles off, the hulls of which,
* before the density came on, could not be wholly seen, seemed now from the
* mast head, not to be above half the distance, as the horizon was visible
* considerably beyond them. . . . Their hulls were much enlarged and
* elongated, and their masts very much shortened. They had precisely the
* prospective appearance of ships in a heeling position." (pp. 387-388)
* [This description resembles Minasi's tilted ships.]
* On p. 389 is another observation, April 28, 1811: a ship "at such
* a distance, that her hull was not visible ; and when viewed from an
* elevation of ninety feet, with a good telescope, half her lower masts were
* intercepted by the ice on the horizon. Now, at the elevation from which
* this ship was seen, the horizon, under common circumstances, would be nine
* miles distant ; and from the knowledge of the dimensions of her masts,
* I estimated the portion of the hull and masts intercepted by the horizon,
* at about 22 feet ; consequently, her distance beyond the horizon must have
* been at least 4½ miles, and her distance from us not less than 13½."
* [In addition to the quantitative estimates, notice that all these were
* seen during the normal superior-mirage season.] It had been a bright,
* sunny day; at 11 p.m., the officer of the watch reported "that the ship to
* the eastward of us, appeared to he forced by the ice upon her beam ends ,
* or into an heeling posture. I immediately ascended the deck, and having
* cleaned the glasses of a good telescope, I hastened to the mast-head. I
* at once attributed the cause of the deception to unequal refraction. This
* ship, which, two hours before, was 4½ miles beyond the visible horizon,
* now appeared as far within it, and was in every respect deformed like the
* ships above mentioned." The intervening ice was "compact and motionless".
* "The horizon on this occasion, between the east and north, though
* continuous, appeared curiously undulated. There appeared a difference of
* nearly a quarter of a degree, between the elevation of the highest and
* lowest portions of the circumferential boundary." (p.390)
* On p. 391, Scoresby notes that these refractions "have usually
* occurred in the evening or night, after a clear day." He correctly
* infers that "two streams of air of different temperatures" are involved;
* but unfortunately supposes that "an irregular deposition of imperfectly
* condensed vapour" may produce the phenomenon.
*
* Also noteworthy for a brief discussion of halo phenomena on p. 393:
* here Scoresby criticizes Huygens's suggestion of circular cylinders as
* the cause, remarking that "It is, however, probable, that such a form
* of hail does not occur in nature, though snow or hail of a prismatic or
* spicular form is not uncommon in the polar regions."
* There are also remarks on the ice-blink on pp. 299-300; and an
* interesting discussion of sea-ice and icebergs in Chapter IV, where the
* word "effulgence" occurs in connection with seeing icebergs at night.
*
* Available at
* https://archive.org/details/accountofarcticr01scor/page/390/mode/2up
*
* and at the Biodiversity Heritage Library.
*
* On the title page of the original volume, the author's name is
* W. Scoresby Jun. F.R.S.E.
* Cited by Prof. Everett (1874).
* Thanks to Eric Frappa for pointing this out!
* BIOT & ARAGO (details)
* This gives the real story of the expedition: how Delambre and Méchain
* began the project, to determine the length of the meter; how the
* southern part of the arc was lost by Méchain's death; and how the
* completed part was published by Delambre in Base du Système
* métrique . The work reported here was done in 1806-07. The very
* breezy Introduction (it is explained in a somewhat apologetic Note) "est
* tirée d'une notice lue par M. Biot, à la séance publique de
* l'Académie des Sciences, pour l'année 1810." It gives the general
* public the bare outlines of how geodesy is done -- along the way,
* offering one of the earliest comparisons of the smoothness of the Earth
* to the peel of an orange (p. vi) -- and reviews the great
* accomplishments of French geodesists, from Picard (1670) and the
* Cassinis, through "Bouguer, Godin, la Condamine, Clairaut, le Monnier,
* Maupertuis et La Caille, tous nos compatriotes, et membres de
* l'Académie des Sciences".
* "Malgré tant d'efforts, malgré tant d'entreprises, on pouvait
* faire mieux encore; . . . les instrumens d'Astronomie étaient bien
* éloignés alors de la perfection qu'ils ont maintenant acquise,
* perfection telle, qu'on peut régarder comme le dernier terme de la
* précision que l'on atteindre par des évaluations mécaniques, surtout
* depuis qu'un autre français, Borda, aussi membre de l'Académie des
* Sciences, eut trouvé le secret d'atténuer indéfiniment les erreurs
* des observations partielles, en les faisant suivre et succéder les unes
* aux autres sur le limbe circulaire de l'instrument auquel il a donné le
* nom de cercle répétiteur." (p. viii)
* So (p. ix), the Bureau des Longitudes has chosen Arago and Biot to
* finish the job. The big problem (p. xi) is that one of the sides of the
* Yvice triangle must be some 160 km long, "environ quarante et une lieues
* de longueur. [ Assuming, as the footnote says, a league of 2000 toises;
* "je n'ai employé cette dénomination vague que pour rendre sensible à
* l'esprit la grandeur de nos triangles, par des évaluations encore
* habituelles pour beaucoup de personnes, mais que, sans doute, avec le
* temps, on finira par abandonner pour les évaluations métriques qui ont
* sur les autres l'avantage d'avoir toujours, et partout, la même
* signification." -- now, read on: ] A de si grandes distances, des
* signaux de jour auraient été complètement invisibles. On devait y
* suppléer per des lampes à courant d'air, derrière lesquelles on
* plaçait de grands miroirs de métal poli, pour réfléchir la lumière,
* et toutes les observations devaient se faire de nuit."
* Desierto de las Palmas is so called "parce qu'il y croît en
* abondance une petit espèce de palmier à feuilles en éventail, que les
* botanistes nomment le chamærops humilis ." (p. xii)
* Then come all the anecdotes: Biot's ship is driven by a storm to the
* tiny islet of Espalmador, inhabited only by a lighthouse keeper and a
* family of poor fishermen. "Jamais on ne vit de plus profonde misère;
* mais, dans cette misère même, il y avait encore de la vanité: le
* gardien de la tour méprisait beaucoup les pauvres pêcheurs." (p. xiv)
* There are the French consuls who helped the expedition, only to lose
* everything later, having to seek refuge in France. (p. xvi) There is
* the loss of one repeating circle, broken in shipment (p.xvii). He
* describes the wonderful view of the Kingdom of Valencia (p. xviii),
* including the site of Méchain's death and entombment; and "les tours
* de la brillante ville de Valence, heureux séjour du peuple le plus
* insouciant et le plus frivole. Mais ces beautés . . . n'avaient alors
* pour nous aucun attrait. Tout remplis, de la seule idée qui nous
* occupait, nous ne songions, nous ne pouvions songer qu'à nos travaux,
* et aux invincibles obstacles qui . . . ." (Well, you get the idea.)
* Here is the story of the tents blown into the sea by a gust of wind;
* "et nous n'avions pu en préserver notre pauvre cabane qu'en passant
* par-dessus des câbles, et la liant au rocher." (p. xix)
* After 2 months of futile effort, they figured out how to spot the
* signals at Ybice, by pointing the telescope to the summit of Campvey
* just after sunset. "Je ne saurais exprimer l'émotion que nous
* éprouvâmes, lorsqu'après tant de peines et tant de doutes, nous
* eûmes enfin la certitude de réussir." (p.xxi) And then Biot
* dramatically reveals Méchain's letter, to top it off!
* We also have the story of the station in the Favaretta mountains
* where Arago tried to establish a station; "mais nous fûmes obligés d'y
* renoncer, à cause de l'abondance des neiges qui couvraient presque
* tout-à-fait les tentes, et aussi parce que les brigands, maîtres de
* ces montagnes, exigeaient que l'on fît un traité avec eux pour avoir
* le droit d'y séjourner." (p. xxii)
* Then there is the episode where Biot leaves the English safe-conduct
* with Arago and promptly gets himself captured by Ragusan pirates. (p. xxvi)
* The original note of 1810 is now available as a PDF file at
* http://www.academie-sciences.fr/Membres/in_memoriam/Biot/Biot_pdf/Notice_EsFr_1810.pdf
*
* But of course our real interest is in the refraction observations.
* These commence on pp. 84-85: "en observant Iviza un instant auparavant,
* la lumière de cette station nous paraissait partagée en plusieurs
* lumières distinctes et bien séparées . . . ." (25 Dec. 1806) This
* story continues on p. 106: "Tems parfaitement calme depuis plusieurs
* jours. . . . Mais à la quatrième ou à la sixième . . . , l'un de nous
* commenc,a de voir à Campvey deux lumières, exactement dans la même
* verticale et éloignées l'une de l'autre d'une quantité que, sur le
* fil, on estima au moins de trois minutes. La vraie lumière . . . était
* à sa place ordinaire; l'autre . . . était plus élevée dans le ciel
* . . . ; elle était aussi plus grosse, plus dilatée, plus irisée." They
* first took it to be a star. There was a problem caused by the two
* observers requiring different eyepiece settings; but when "l'autre
* observateur dut amèner sa lunette sur ce même point, non-seulement il
* apperçut deux lumières, mais il en vit trois et quatre les unes
* au-dessous des autres. . . . Quelquefois on appercevait plus de quatre
* lumières . . . . Le autres, toujours plus élevées dans le ciel, se
* formaient ensuite successivement . . . ." The regular image brightened as
* the others appeared; sometimes the extra images were still brighter than
* the bottom one. No color reported. Biot's monograph is cited.
* Similar phenomena are reported on pp. 134-135, in observing the signal
* at Desierto from Cullera. Again, the multiplicity of images is
* accompanied by brightening.
* It gets really interesting in the observation from Mongò (p. 144),
* in which DISPERSION is at last reported (though not recognized):
* "Tems parfaitement calme, mais vaporeux; lumière de Cullera bien
* visible; celle du Desierto faible, quelquefois diffuse comme si on la
* voyait à travers une gaze; d'autres fois alongée en un
* parallélogramme vertical; d'autres fois brillante et bien terminée.
* Pendant la 16e observation, on l'a vue double; on l'a vue double aussi
* pendant la 20e. Dans ces deux cas, l'une des deux lumières paraissait
* rouge, l'autre paraissait d'un vert pâle. La première nous a semblé
* à tous deux répondre à la place qu'occupait un instant auparavant la
* lumière véritable; le seconde image, celle qui était verte,
* paraissait, dans le champ de la lunette, au-dessous de la lumière
* rouge, ce qui la mettait au-dessus en réalité, puisque les lunettes de
* nos cercles renversent les objets; en sortant de la cabane, nous
* observâmes qu'il y avait des masses de brouillards moutonnées sur la
* mer, comme lorsque nous observâmes de la station de Desierto plusiers
* lumières à Campvey." (13 Feb. 1807; both B&A again.)
* Another DISPERSION report comes from La Mola de Formentera; "Les
* habitans de cette petite île sont très-peu nombreux, et ceux d'Yviza
* les regardent comme des sauvages, quoiqu'ils ne soient pas eux-mêmes
* très-civilisée." (p. 170) But I digress; the good stuff is on p.
* 175, where we have both Arago and Biot observing again, 27 April 1807.
* The light on Mongò was ordinarily "un petit point rond bien terminé;
* mais quelquefois elle s'alongeait verticalement et occupait plus d'une
* minute décimale. Il nous a semblé remarquer alors que cette image
* n'était point de même couleur dans toute son étendue. le rouge était
* en haut, le verd en bas dans la lunette qui renverse. . . . Tems calme."
* Full title is:
* Recueil d'Observations Géodésiques, Astronomiques et Physiques,
* exécutées par ordre du Bureau des Longitudes de France, en Espagne, en
* France, en Angleterre et en Ecosse, pour déterminer la variation de la
* pesanteur et des degrés terrestres sur le prolongement du Méridien de
* Paris, faisant suite au troisième volume de la Base du Système
* métrique; rédigé par MM. Biot et Arago, Membres de l'Académie des
* Sciences, Astronomes adjoints du Bureau des Longitudes, etc.
* (Umberto Eco mentions this in section 84 of ``Foucault's Pendulum'',
* calling this title ``phantasmagorical''!)
* available at Google Books
* SUPERIOR MIRAGES of SHIPS
* cf. Rees, 1988, and Lehn & Rees (1990) for inversion
* WILLIAM SCORESBY's Journal
* The full title is "Journal of a Voyage to the Northern Whale-Fishery;
* Including Researches and Discoveries on the Eastern Coast of West
* Greenland, Made in the Summer of 1822, in the Ship Baffin of Liverpool"
* The refractions are discussed on pp. 96-97: "Hummocks of ice assumed
* the forms of castles, obelisks, and spires; and the land presented
* extraordinary features. In some places, the distant ice was so
* extremely irregular, and appeared so full of pinnacles, that it
* resembled a forest of naked trees; in others it had the character
* of an extensive city, crowded with churches, castles, and public
* edifices."
* NOTE the footnote on pp. 96-97 (spanning Plate II) warning the reader
* that phenomena that were not contemporaneous are depicted together in
* the Plates!
* Looming of distant land, well over 100 miles away, is described on
* pp. 106-108.
* There is another short account of mirages on pp. 117-119: "The ice
* about the horizon assumed various singular forms: -- hummocks became
* vertical columns, -- floes and fields arose above the horizon, like
* cliffs of prismatic-formed spar, -- and, in many places, the ice was
* reflected in the atmosphere at some minutes elevation above the horizon."
* He then describes mirages of ships. . . . "The most remarkable effect
* produced, was on the most distant objects, the interesting appearances
* of which not being discernable without the use of a telescope, probably
* escaped general observation."
* [Note observation of CONCAVE surface.]
* The main account of mirages is on pp. 163-173; see Plate V, between
* pp. 164 and 165. "Often the hummocky parts of the horizon were reared
* into various architectural figures of extraordinary elevation : and
* occasionally, as observed in a former instance, the whole distant margin
* of ice was deeply serrated, in resemblance of an innumerable collection
* of spires and pinnacles, or in the form of a thick forest of naked trees."
* (p. 164) . . . . ". . . the space in which the ship navigated seemed to
* be one vast circular area, bounded by a mural precipice, of great
* elevation, of basaltic ice. . . . And it should also be observed, that
* these phenomena were principally telescopic, both the ships and images
* being so distant, that, to the naked eye, they only appeared as
* indistinct specks." (p. 165)
* "The general telescopic appearance . . . is frequently that of an
* extensive ancient city, abounding with the ruins of castles, obelisks,
* churches, and monuments, with other large and conspicuous buildings.
* Some of the hills often appear to be surmounted with turrets,
* battlements, spires, and pinnacles; while others, subjected to another
* kind of refraction, exhibit large masses of rock, apparently suspended in
* the air, at a considerable elevation above the actual termination of the
* mountains to which they refer. The whole exhibition is frequently a grand
* and interesting phantasmagoria. Scarcely is the appearance of any object
* fully examined and determined, before it changes into something else.
* It is, perhaps, alternately a castle, a cathedral, or an obelisk: then
* expanding and coalescing with the adjoining mountains, it unites the
* intermediate valleys, though they may be miles in width, by a bridge of
* a single arch of the most magnificent appearance." (pp. 166-167)
* He continues: "The cause of these phenomena, as far as they depend on
* refraction, is, I imagine, the rapid evaporation which takes place in a
* hot sun, from the surface of the sea; and the unequal density occasioned
* by partial condensations, when the moist air becomes chilled, by passing
* over considerable surfaces of ice. The vapour produced by evaporation
* and partial condensation, is sometimes perceptible to the eye, rising
* like transparent steam in all directions, in little curling clouds, and
* passing along with the breeze near the surface of the sea. Its influence
* can sometimes be perceived at the distance of a few fathoms, or, perhaps,
* half a furlong, by the tremulous motion it appears to give to all bodies
* on the water or near it. In this case, it has a tendency to produce a
* serrated or basaltic appearance of the ice on the horizon, similar to
* what occurred on the 10th and 19th of June. But at other times, when
* repeated, well-defined and proportionate images of ships appear in the
* air, the vapour giving rise to the unequal density, obtains more of a
* stratified arrangement. In its distortive effect, it seems to act like
* clear glass, of unequal surface or thickness; consequently it disfigures
* all objects seen through it. In its looming effect, or that property
* of it by which bodies on the horizon, or beyond, appear to be greatly
* elevated, or suspended, as it were, in air, it seems to act by that kind
* of refraction common to other mediums, when the density about the object
* seen is greater than at the eye of the observer. The lesser density of
* the air about the observer, arises from the elevated position he occupies
* when at the mast-head, where the phenomena are always the most striking.
* Hence, while near objects, which are seen through a very rare portion of
* this vapour, are little or nothing elevated: bodies at the distance of the
* horizon, which are seen through a mass of it several miles in thickness,
* are elevated ten, fifteen, twenty, or even thirty minutes of altitude.
* And when ships or ice within a few furlongs distance are disfigured by
* the action of this vapour, so as to present a varying and tremulous
* outline; other similar objects, at the distance of several miles,
* are, perhaps, steadily elevated. In most cases, the refracted portion
* of the distant ice is closely connected with the ice of the horizon,
* from whence it takes its rise; and when it assumes the columnar form,
* it presents the appearance of a vast amphitheatre, which is so disposed,
* that every observer, whatever may be his position, imagines himself to be
* in the centre of it. But in some instances, and these not unfrequent,
* the stratum of refracted ice is completely detached from the horizon,
* and appears to form a white horizontal streak in the lower part of the
* atmosphere. And occasionally, multiplied images of the ice, as well as
* other objects, occur, forming a parallel vertical series." (pp. 167-169)
* [This is followed by a long footnote, referring to Wollaston's paper,
* and Brewster's works, of a similar nature.]
* He then describes the appearance of the highest parts of the land seen
* above the duct, and correctly concludes that "the tops of the mountains
* were above the vapour, . . . so that no influence could be exerted by the
* refractive medium, but on the base of the land, which was concealed by
* the looming of the ice." (pp. 171-172)
* "As the more extraordinary and beautiful effects of unequal
* refraction cannot be fully discovered, without the use of a telescope,
* they escape general observation; and as the looming of the distant ice,
* or distortion of objects, is the most common effect of this state of the
* atmosphere, it becomes a considerable annoyance to persons not interested
* in the phenomena. As in this case, the vapour gives an indefinite and
* tremulous outline to every object beyond a certain distance;— ships, a
* mile or two off, cannot be recognised ;—a wall of ice seems to surround
* the navigator, the openings and leads in which cannot be discerned at
* a distance;—and, of the actions and employment of remote vessels,
* within sight, a knowledge of which is often of great importance to the
* unoccupied fisher, no correct conception can be formed." (pp. 172-173)
* Now comes the incident of seeing his father's ship miraged (July 24):
* "On my return to the ship, about 11 o'clock, the night
* was beautifully fine, and the air quite mild. The atmosphere,
* in consequence of the warmth, being in a highly refractive state, a
* great many curious appearances were presented by the land and icebergs.
* The most extraordinary effect of this state of the atmosphere, however,
* was the distinct inverted image of a ship in the clear sky, over the
* middle of the large bay or inlet before mentioned,---the ship itself
* being entirely beyond the horizon. Appearances of this kind I have
* before noticed, but the peculiarities of this were,--- the perfection
* of the image, and the great distance of the vessel that it represented.
* It was so extremely well defined, that when examined with a telescope by
* Dollond, I could distinguish every sail, the general `rig of the ship,'
* and its particular character; insomuch that I confidently pronounced it to
* be my Father's ship, the Fame, which it afterwards proved to be;---though,
* on comparing notes with my Father, I found that our relative position
* at the time gave our distance from one another very nearly thirty miles,
* being about seventeen miles beyond the horizon, and some leagues beyond
* the limit of direct vision. (Plate V. fig. 2.) I was so struck by the
* peculiarity of the circumstance, that I mentioned it to the officer of
* the watch, stating my full conviction that the Fame was then cruizing
* in the neighbouring inlet. (pp. 189-190; the Plate, between 164/165)
*
* Thanks to Mila Zinkova, for prompting me to include this item!
*
* Available at Google Books:
*
* https://books.google.com/books?id=n-MUAAAAQAAJ&source=gbs_navlinks_s
*
* Info kindly supplied by A.R.Macdonald, librarian at ROE:
* Henry Home Blackadder
* "In adverting to this subject, one can hardly avoid noticing the
* remarkable inattention of not a few to what is passing under their
* immediate view, while they eagerly search after that which is distant,
* and far removed from the sphere of their contemplation. . . . Is nothing
* interesting but what is distant?"
* GIUSEPPE DEL RE's comments on Minasi and the terminology
* (dedicated to the Duke of Calabria)
* The tides and associated flows are discussed on pp. 30-31.
* Then comes the interesting discussion (p. 32):
* "A rare and surprising phenomenon in the Strait of Messina is the
* Iride Mamertina , called the Fata Morgana by the natives." He cites
* Ribaud for information on this as well as the tides.
* "P. Minasi of Silla . . . claims that the beautiful Fata Morgana is
* seen only from Reggio; but it seems undoubted that it is seen also from
* Catona, from Gallico, from Villa s. Giovanni and from Messina, city
* where it has the name of Iride Mamertina ."
* This is the reference mentioned (but not cited) by Bayfield (1835)
* whose quotation is not strict. The original reads:
* "At one moment, the rippled surface of a lake was before my eyes; at
* another time, a thick plantation appeared on either side of me; the
* waving of the branches was to be seen, and this view was only changed
* for that of a distant glimpse of a city; the mosques and minarets were
* distinct, and several times I asked my Bedouins if that were not Suez
* before us; but they laughed and said it was all sand; and what appeared
* to me a city, a forest, or a lake, the nearer I endeavoured to approach
* it the farther it seemed to recede, till at last it vanished altogether,
* `like the baseless fabric of a vision, leaving not a wreck behind.'
* "If I were to speak of the nature of the Mirage from my own
* sensations, I should say, it was more a mental hallucination than a
* deception of the sight; for, although I was aware of the existence of
* the Mirage, I could not prevail on myself to believe that the images
* which were painted on my retina were only reflected, like those in
* a dream, from the imagination, and yet so it was."
* Background on the next two items. Henry Wolsey Bayfield had spent
* several years in mapping the Great Lakes; the Royal Navy was worried
* about naval warfare on the Great Lakes after the War of 1812, and
* needed maps. As the war scare on the border between Canada and the
* United States calmed down, the Navy reduced the mapping effort; but
* Bayfield, who had grown to enjoy his work in Canada, persuaded the
* Admiralty to extend the effort to the largely unmapped St. Lawrence
* estuary. But his exertions under harsh conditions had brought him
* some severe medical problems; so in staffing the new vessel under his
* command, he asked that a medical officer be added to the crew. This
* turned out to be Dr. William Kelly, "an experienced naval surgeon".
* These are volumes 54 and 55 of the Publications of the Champlain
* Society. The index to both volumes is at the end of the second one.
* The first volume contains Bayfield's notes on two mirages later
* published: the first (on pp. 175-176) is the mirage of June 19,
* 1832, published in Bayfield's 1835 note in the Nautical Mag.; the other
* (pp. 380-381) is the mirage of 13 Sept. 1835.
* Dr. William Kelly's first mirage paper
* Here he introduces some half-baked ideas, later retracted. But he has
* already discovered for himself the difference between the inferior and
* superior mirages. In the original text, he cites only Humboldt; in the
* later commentary, he reviews the papers by Latham, Vince, Huddart,
* Wollaston (whom he consistently calls "Woolaston"), Biot, and Parry.
* He says he has seen the mirage in Egypt. Note the FOG in the title;
* also (p.11): "There was generally with the mirage an appearance of a fog
* bank on the horizon . . . . The air within the horizon was at the same time
* perfectly clear."
* Effect of HEIGHT OF EYE mentioned repeatedly: "All these unusual
* appearances were generally lost in ascending the rigging from ten to
* thirty steps, when objects were seen in their natural shapes."
* Effect of DISTANCE noted: "The appearances differ much; owing,
* apparently, to the ships being more or less remote." And, in discussing
* Vince's report on p. 34, he says, "The refracted objects were all without
* the natural line of the horizon; those within it retaining their usual
* appearance." (This point was already made by Vince.)
* HEIGHT and DISTANCE COMBINED: (p. 12): ". . . during the mirage, which
* occurred in a calm with a considerable swell of the sea, the appearances
* presented by two small islands or rocks, at different distances from us,
* was very remarkable; for as the vessel rose on the wave, the more
* distant seemed to sink, and the nearer to be raised up; and again as the
* vessel sank, the first rose, and the near one was lowered. Even the
* different parts of the same island were variously affected, appearing to
* dance as the vessel rose and fell."
* Reflection in an apparently SMOOTH MIRROR (inf. mir.): "The portion of
* reflected sky between the inner islands and the vessel, resembles a
* perfectly smooth lake." (p. 17)
* MIRAGE and DIP: (p.20): he found the large dip of the inferior mirage
* ". . . so remarkable a feature, that I distinguished this in my notes as
* the mirage with shortened or depressed horizon, whilst the other was
* designated the mirage with elevated horizon, on account of the contrast
* between them . . . ", citing Humboldt's earlier work.
* Captain Bayfield's first 3-image report (with Kelly); seen June 19, 1832
* With air 5° F warmer than sea surface, a vessel 7 miles away was seen
* "with her hull occasionally raised, so as to shew it distinctly above
* the horizon, although the height of our eyes was not over eleven feet.
* Her sails appeared elongated laterally, but were perhaps only shortened
* vertically, which made then appear so elongated." (This probably
* explains many other reports of APPARENT HORIZONTAL MAGNIFICATION as well.)
* There was a very light breeze from the west.
*
* This item is followed by two rather ordinary inferior-mirage reports
* from A. Inderwick in Mexico, and R. R. Madden in Egypt, on pp. 93-94, and
* p. 94, respectively. The latter's comment, taken from his "Travels in
* Turkey, Egypt, . . . ", that "I should say it was more a mental hallucination
* than a deception of the sight; for, although I was aware of the existence
* of the mirage, I could not prevail on myself to believe that the images
* which were painted on my retina were only reflected, like those in a
* dream, from the imagination, and yet so it was" -- is apposite.
* (Though to him "the mosques and minarets were distinct," the Bedouins
* "laughed at me, and said it was all sand.")
* FIRST observation of FIVE IMAGES?
* William Kelly, M. D. was an acute observer:
* "When my attention was directed, some years since, to the different
* forms of objects, seen through mirage in the St. Lawrence, one of these,
* which I particularly remarked, was the flower-pot shape assumed by small
* islands, when affected by the mirage, which depends on the contact of warm
* moist air with a surface of water colder than its dew point. Whatever
* the real shape of the island, or rock might be, its top seemed raised and
* flattened; generally extending in a straight horizontal line so far on
* each side, as at least to equal the base in extent; often beyond it;
* whilst, midway between the base and distorted top, the figure was
* contracted, having the appearance of a neck. When two islands lay close
* together, these flattened tops sometimes met, giving the appearance of an
* arch from one to the other. In all cases of mirage, depending on the same
* cause, the tops of objects seemed straight and horizontal in the same way,
* but the sides were like a wall. They frequently presented an appearance
* as if they were horizontally stratified."
* He describes an instance in detail: "A line answering to the horizon,
* was also seen on a level with the upper flat part of the inverted image of
* the island, and extending from it to a sandy point on the main. The true
* horizon was quite distinct, and well marked beneath. The sandy beach
* between us and the point seemed raised like a wall."
* Another case "presented to the naked eye nothing more than the flat top
* and walled sides usually seen in this form of mirage. But on examining it
* carefully with a telescope, in some parts of the flattened top, the
* picture of a beach was seen above the trees; thus shewing that this form
* also depended upon a second inverted image lying above, and confounded
* with, the upright one."
* "All the various forms assumed by objects, under the influence of this
* mirage, seem to be the result of two or more images, alternately erect and
* inverted, either distinct or mingled together in a greater or lesser
* degree."
* In June, 1832, "in passing Point des Monts, where the breadth of the
* river is very considerable, we saw the three images distinctly marked,
* such as they have been described by Vince and Scoresby. . . . We have
* frequently since seen treble images in the estuary and gulf . . . ."
* GOOD ADVICE TO OBSERVERS:
* "A telescope, if at hand, should always be employed in observing mirages
* of any kind, as it enables us to detect particulars, that would escape the
* naked eye. On one occasion, to the naked eye, the hull of a ship seemed
* raised to an enormous height, and the sails very small, the telescope
* shewed three distinct images. . . . By the help of the telescope we were
* afterwards enabled to detect five distinct images, though the whole gave
* to the naked eye the impression of only one almost shapeless mass. . . ."
* Another time, with the air 48° and the water 39°.5, ". . . a vessel
* with all sail set, at one moment looked like an immense black chest, no
* sails or masts being visible. On observing her for a time the black body
* seemed to seperate horizontally into two parts; and two sets of mingled
* sails occupied the intervening spaces, with one set of very small sails
* above. The figures afterwards became more distinct, and three images were
* clearly discerned. Another vessel changed also from the form of a great
* square flat-topped chest, to five distinct images, the upper with sails
* erect, and the two lower double images with their sails rather confusedly
* intermingled. A raised horizon was parrallel to the upper figure of the
* hull. . . . Captain Bayfield and Mr. Bowen observed five distinct images of
* another vessel after I left the deck. When I first noticed extraordinary
* appearances, like those I have endeavored to describe, I was not aware of
* the advantage of employing a telescope for the examination of objects at
* inconsiderable distances." [spelling errors all sic ]
* "It seems probable that the horizontally stratified appearance, which
* the coast often assumes under this species of mirage, may be the effect
* of multiplied images of the horizon, or level sea at its base. The number
* of images may well exceed five, as we find they do three, which I believe
* was the greatest number hitherto noticed by any observer."
* IMPORTANCE OF MIXING in stratified waters:
* "Several rivers empty themselves into the sea at this place [the Mingan
* islands], the waters of which, in calms, float on its surface, which thus
* is sometimes several degrees warmer than the water at a depth of a few
* inches. A moderate current of air, which amongst small islands is often
* partial, sometimes, by agitating the water at one place, renders the
* surface there cold, whilst it continues warm in places sheltered from the
* wind. We have hence occasionally strange combinations of mirage." Thus,
* starting from an ordinary inferior mirage, where "The horizon on this side
* was low and near -- a rock, three miles distant, seemed above it. As the
* breeze sprung up from the S.W. the horizon receded beyond this rock, and
* the islands generally appeared to have flattened tops, shewing the mirage
* of the opposite kind. But the extreme points of the most distant island
* seemed still in the air, notwithstanding, the island generally presented
* the same flat level top as the others -- thus shewing, in its different
* parts, the opposite forms of mirage at the same time."
* ALTERNATION OF ERECT AND INVERTED IMAGES DISCOVERED:
* "Whatever the number of images may be, they appear in every instance to
* be alternately erect, and inverted."
* DISCONTINUOUS HORIZON:
* "But on one occasion near the Labrador coast, the point of junction of
* the two species of mirage was so well marked that it appeared like a step
* in the horizon."
* ASSOCIATION WITH STRAITS:
* "The most remarkable mirages over water have occurred in straits; those
* seen by Mr. Vince at Dover, and the celebrated Fata Morgagna at Measina.
* In the St. Lawrence they are most frequently observed, and present the
* greatest varieties in similar situations: as at Bic, Point des Monts,
* and the strait of Belle-isle." [typos strictly sic .]
* VARIATIONS IN DIP:
* He also cites a case in which the dip, measured with the dip sector,
* increased from 3' 15" to 4' 11" as the water temperature changed from 43.5
* to 46.5 F (both as seen from 12 ft. 6 inches elevation).
* Footer says "ENLARGED SERIES. -- No. 6".
* MICHELE SAFFIOTI's letter
* This is the second edition (1837), placed here to be next to Capozzo's
* disastrous derivative. The author's name is spelled "Saffioti" on the
* title page, and at the end. That spelling (according to Google Books's
* "Ngram viewer") was the more common in written material before 1874.
* Both Boccara (1902) and Costanzo (1903) spell his name "Saffiottï
* (with two t's); since then, the two-t spelling has dominated. The two
* spellings are about equally common on the Web today . . . .
* He hoped to see images vaguely colored with the colors of the rainbow.
* (pp. 9, 10) These colors are mentioned again on pp. 14 and 20 (referring
* to Minasi),
* He quotes Facellus (p. 14), and Angelucci's letter (p. 15).
* Then there are reports of the 26 April 1828 display, beginning with a
* "current of transparent vapor." (p. 17)
* Kircher, Allegranza (!) and Minasi appear on p. 19; he thinks none of
* them were observers, and that only Angelucci saw the Fata Morgana.
* The second part, beginning on p. 21, describes the geography around
* the strait. The tidal currents are treated on pp. 25 - 28. Then comes
* his theory, full of crystals and "vesicular vapors" (!) (p. 33)
* At least he understands that the sea and the air must both be perfectly
* calm to produce the F.M.
* Available on the Web at
* https://archive.org/details/bub_gb_HOxu7xksWzMC
* GUGLIELMO CAPOZZO's review of the Fata Morgana (via Saffiotti)
* The Introduction, and particularly the "Literary Appendix" on pp. 36
* to 38, shows that this is another work devoted to Sicilian patriotism;
* so the uncritical acceptance of Giardina as an authentic F.M. observer
* is hardly surprising.
* Quotes Giardina (1758) and Angelucci/Kircher in extenso on pp. 74-76,
* evidently believing that Giardina actually observed the 1643 display.
* After quoting Angelucci's account in full, the author says:
* "Our Padre Domenico Giardina of the society of Jesus describes more
* fully the same phenomenon seen in Messina on the 14th of August of that
* same year 1643." But, of course, Giardina didn't see that display;
* so the "added" details are all fabricated. (Cf. the growing embroidery
* of the New Haven "ghost ship", or the spurious details added to Minasi's
* account by Nicholson and Brewster.)
* There are many errors. He consistently calls Saffiotti "Salfiotti",
* consistently calls Angelucci "Angellucci", and mentions Allegranza
* (footnote, p. 72). And, as he plainly knows little about physics or
* optics, his attempts to explain the reflections with "vesicular vapors"
* and the like (p. 88) are useless nonsense.
* A final note, at the end (p. 92), says this article is an extract of
* the letter from Saffiotti cited on p. 72, note 1, with some additions.
* Those additions include the notion that Giardina saw the 1643 F.M.
* from Messina!
*
* Unfortunately, this wrong account has been propagated by careless
* readers: Consolo (in his 1993 Italian original, and then again in
* translation in 2006), and the ignorant Marina Warner (also in 2006).
* Then Capozzo's Italian was republished again in 2011 by Séstito.
* This is just as useless as Boccara (1902) says.
* The title page of the volume adds “con aggiunte e note per
* Guglielmo Capozzo” to the title given below; and Capozzo signed the
* dedication, the preface "to the readers", and the Introduction.
* The footers on pp. 17, 33, 49, 65, 82, etc. say "Capozzo Vol. I."
* So he is clearly the editor and effectively the publisher.
* Available at Google Books, and at the HathiTrust site.
* VINCENZO CONSOLO's essay on the Strait of Messina, with Fata Morgana errors
* repeats Capozzo's phony story (hence its placement here).
*
* A beautiful "coffee-table" book (quarto: 9x13 inches = 24x33 cm), with
* 34 color plates and 65 b/w in the text. The body type is large (about
* 12/15); the references and notes are about 11/13; and the photo credits
* on p. 183 are about 8/10.
* The contents exactly fit the title: it's mostly a picture book of
* views of the Strait of Messina, from the Middle Ages to the middle of
* the 19th Century.
* The subtitle "Con un saggio di Gioacchino Barbera" refers to Barbera's
* essay "Per un'iconografia dello Stretto di Messina" on pp. 41-64,
* followed by 3 pages of notes -- considerably longer than Consolo's text
* on pp. 15-37, followed by only 3 column-inches of notes on p. 38.
* The last 5 pages of Consolo's text are enclosed in quotes here, and
* set off by a break, as they are taken from his 1988 publication "Fra
* Contemplazione e Paradiso" with N. Rubino, as indicated by his final
* note on p. 38 here. The transitional paragraph on p. 33 that leads in
* to this story was reduced to a single sentence when this was translated
* by Mark Chu for Bouchard and Lollini's 2006 book.
* Barbera's essay is followed by 6 pages of biographical notes, and
* 18 pages of short notes on some of the works of art that are reproduced,
* prepared by Giovanni Molonia. Five of these are works by Willem Fortuyn,
* including his engraving for Minasi's Fata Morgana review.
* Then comes a 5-page bibliography, which mentions an unpublished letter
* by Gallo on the Fata Morgana of 18 Aug. 1768.
* The emphasis of the book is on art history; but it's garbage history,
* with no regard for factual accuracy in Consolo's text.
*
* Considering Consolo's repetition of Capozzo's false account of the
* 1643 Fata Morgana display, the main value of this for our purposes is
* the re-publication of Minasi's dissertation in full.
* Pages 159-168 contain a verbatim transcript of Minasi's dissertation,
* complete with its notes. Here there are some discrepancies with the
* original, starting with the extract from Pliny's Historia Naturalis:
* the original cites this as book VII, but Consolo's copy says book IV.
* The formal closing of the dedication has also been edited slightly: a
* comma was inserted after "Roma", and the tildes over the m's in the
* signature were omitted.
* Similar edits were made in the Proemio, including the addition of
* typos like "gravissimus" for "gravissimis" and "dibiis" for "dvbiis"
* in the quoted inscription. [As "i" and "u" are adjacent keys on modern
* keyboards, it's obvious how these were produced.] These same copying
* errors appear in the version of Minasi's text reproduced in Séstito's
* book; so that was probably copied from Consolo, rather than from the
* original.
*
* Likewise, there are changes in the reproduction of Minasi's footnotes,
* which have been converted to end-notes here, with re-numbering within
* each Chapter (instead of each page, as in the original.) The change
* in format from Minasi's small single columns to much wider double
* columns with narrow margins has compressed Minasi's 102 pages to just
* 20 pages.
* However, the re-numbering was not extended to the cross-references
* within the Notes. So "Cap. III, § 8, nota 1" that is cited in notes
* 7 and 30 to Cap. V is now note 11; and the "Cap. III, § 8, nota 2"
* cited in note 28 is now note 12. But everything is here, including
* the notes in Cap. IV that discuss the plagiarism of Angelucci's account
* by Giardina.
* Evidently, Consolo was another of those careless writers who cite
* references (and, here, even re-publish them) without reading them.
* VINCENZO CONSOLO (in translation) serving up Capozzo (1840)
* (and so placed here out of chronological order):
* The translator has rendered Angelucci's account in graceful English,
* on pp. 196-197. Then we have:
* "And the Calabrian Jesuit sees that Fata Morgana precisely on
* the feast of the Assumption -- the great feast of the patron saint
* in Messina on the day of 15 August -- creating the suspicion that
* his might be a devout fantasy. This is all the more so for the fact
* [sic!] that another Jesuit, Father Domenico Giardina, has the same,
* identical vision, like the reflection on the second side of a double
* mirror, with only the temporal displacement of barely a day, on 14
* August of that same year of 1643, from the opposite side, from Messina.
* [Here, footnote 21 cites Capozzo as the reference.] The story of the
* Calabrian is identical to that of the Messinese (which we would like to
* reproduce here if we were not afraid of boring the reader); the details
* are identical, except for the number of the pillars: ten thousand for
* Angelucci, one hundred thousand for Giardina."
* "Identical"! So why didn't Consolo suspect that Giardina's account
* was copied from Angelucci's? And why didn't his editors suspect this,
* and investigate? Instead, he wanders off into airy lyricism, and
* reality and truth are abandoned. Shameful.
* The translator of this essay was Mark Chu, another person very
* interested in Sicilian matters; which may have dampened his critical
* sense.
* This essay (pp. 188-) is called "Views of the Strait of Messina".
* On p. 294, we find it comes from "Vedute dello Stretto di Messina"
* in "Di qua del faro" (1999), pp. 67-91; though I also see it listed as
* a separate publication by Sellerio, Palermo, dated 1993.
* The book says copyright 2006; the publisher's website says 2007.
* Sir Charles LYELL's textbook example of LOOMING:
* "June 14, 1842. - From Queenstown we embarked in a fine steamer for
* Toronto, and had scarcely left the mouth of the river, and entered Lake
* Ontario, when we were surprised at seeing Toronto in the horizon, and
* the low wooded plain on which the town is built. By the effect of
* refraction, or `mirage,' so common on this lake, the houses and trees
* were drawn up and lengthened vertically, so that I should have guessed
* them to be from 200 to 400 feet high, while the gently rising ground
* behind the town had the appearance of distant mountains."
* (No photocopy; this is on P-10 microform.)
* THOMAS MILNER's update of Polehampton's 1815 work
* This version went through many editions; the 1855 one is on Google Books.
* It bears the label "A NEW EDITION, CAREFULLY REVISED" on the title page.
* A copy of the 1848 edition from the U.C. libraries is at the HathiTrust
* website. It seems identical to the 1855 one; and the quality is better.
* The 1846 edition is also at the HathiTrust site.
* In all 3 editions, mirages are in Section 5, "Spectral Illusions",
* of Chapter XVI on "Optical Phenomena": pp. 535-540. It then goes on
* to deal with the Brocken spectre and similar images on mists, which are
* attributed to "reflection". The text returns to mirages on p. 542: "In
* northern latitudes the effects of atmospheric reflection and refraction
* are very familiar to the natives. By the term of uphillanger the
* Icelanders denote the elevation of distant objects . . . ." The mirage
* discussion then continues with Scoresby's observations, Wollaston,
* Jurine & Soret, etc. until p. 543. [Cf. Milner's 1850 book.]
* Note: "upphillingar" seems to be the correct spelling.
* Minasi's stuff about the tides is omitted.
* Dr. William Kelly seems to have been as sharp an observer as Willard Fisher
* "On The Dip Of The Horizon, and Mirages of the Gulf and River St.
* Lawrence. By William Kelly, M.D., Surgeon, R.N., attached to the Naval
* Surveying Party on the St, Lawrence.
*
* "Every one conversant with nautical astronomy is aware that some
* uncertainty always attends observations made with the natural horizon,
* from the varying amount of the dip occasioned by terrestrial refraction.
* The cause of these variations is very obscure. The best authorities seem
* to regard differences of temperature in the air and water as the sole
* cause of the irregular density of the lower strata of the atmosphere on
* which the varieties of the dip depend. It is known that, in general, when
* the water is warmer than the air, the dip is greater than that given in
* the tables; and that when the water is colder than the air, the dip is
* less. But cases occur where the deviations from the tables are found to
* bear little relation, at least in amount, to the relative temperatures of
* the air and water. Some other property of the atmosphere must therefore be
* sought after, by the influence of which the effects of temperature are
* modified."
* He recognizes the two main types: "In one (the mirage of Arctic regions)
* the horizon is elevated, the forms of objects distorted, and frequently
* two, three, or even as many as five images of the same object are seen,
* alternately erect and inverted -- the lowest always being erect. This
* kind of mirage is only met when the water is colder than the air. In the
* other kind of mirage, (the mirage of the desert), the horizon is
* depressed, distant points of land seem raised into the air, the form of
* objects is seldom materially changed, there are never more than two images
* of an object, and when a second is seen, the lower is always inverted, the
* upper erect. When this kind of mirage is seen, the water is usually
* warmer than the air."
* "The mirage with depressed horizon was constantly seen if we had an
* opportunity of observing distant points of land when the water was warmer
* than the air."
* Kelly grants that the temperature difference between water and air is
* the main factor, but thinks humidity plays a part as well.
* "The occurrence of either form of mirage, and its intensity, seemed to
* be affected by other circumstances besides the relative temperatures of
* the air and surface water, and the hygrometric states of the air. Thus
* they appeared more frequently, and their phenomena were more intense in
* calms or light winds than in a fresh breeze." -- with a footnote:
* "Still I have seen both forms in fresh breezes, and the mirage with
* depressed horizon during a strong gale."
* He gives a few extreme examples of dip, and notes a DIURNAL VARIATION in
* dip. The variations of dip parallel those of the mirages:
* "The force of the winds had the same effect on the dip as on the
* mirages. Either the elevation or the depression was comparatively greatest
* in a calm, and least in a breeze. This was often very observable when a
* set of observations was commenced in a calm, and a breeze happened to
* spring up before it was finished."
* On the whole, a careful, cautious argument; should be taken seriously.
* NOTE: This and other selections from Nautical Mag. were plagiarized
* in Vol. 2 of The American Merchant (1859) by "Capt. John H. Bell".
* No.8, August, 1846. Title page says "The Nautical Magazine and Naval
* Chronicle". Available at Google Books.
* Commander Bedford thinks it has to do with water vapor, not temperature.
* See detailed discussion below, following the reprint in J. Franklin Inst.
* I have only a very bad copy of this from a scratched microfiche.
* Full title is "The Nautical Magazine and Naval Chronicle".
* Commander Bedford thinks it has to do with water vapor, not temperature.
* But he recognizes that the difference in temperature of sea and air is
* the decisive factor. He has observed carefully:
* "The occurrence of mirage during strong, or even fresh, winds, can be, I
* imagine, but seldom, particularly of that kind with elevated horizon. . . ."
* Despite the title, this is about mirages. This seems to be a verbatim
* reprint of his Nautical Magazine article, in response to Kelly.
* A curious report, including claims of LATERAL MIRAGE
* ". . . the said light became perfectly distinct , and proved to be, (as
* in a former instance communicated to you, Calais Light , and in a
* position 2 3/4 points from its real bearing. . . . right over the middle
* of the North Sand."
* A Classical allusion: "The pilot of Ulysses was deceived, as Ithaca
* melted into mist . . . ."
* Cited by Lt. Raper.
* Capt. Martin is listed as "Harbour-Master, Royal Harbour, Ramsgate."
* Full title is "The Nautical Magazine and Naval Chronicle".
* Sept. issue.
* HEIGHT DEPENDENCE mentioned for BLACK SEA mirages
* In the section headed "Black Sea" (p. 418), Capt. Leighton says:
* ". . . I have found that dark overcast rainy weather occurs frequently,
* . . . and this weather sometimes clears off suddenly to beautiful clear
* weather, but leaves a miraged horizon. This, when it occurs at night is
* very deceptive, as it cannot then be seen, and may mislead you by false
* altitudes of stars. I have seen it several feet high all round the
* horizon during the day, appearing like broken water, or the tops of trees
* upon a low plain just rising above the horizon, that did not disappear
* until the eye was fifty feet above the sea. I have also observed the
* land to be affected by this mirage, particularly near Cape Fontane."
* EARLIEST BLANK STRIP ?? Note references to "DRY FOG" throughout
* Many good descriptions and a DRAWING of black bars across the Sun!
* The "météore" is evidently a DUCT, which he says is known as "qobar"
* in the language of the Ethiopians. "Toutes les langues éthiopiennes
* ont un mot spécial pour le désigner et pour éviter les périphrases."
* (According to the E.B. (9th ed.), d'Abbadie compiled a catalog of
* existing Ethiopian manuscripts; see the article on Ethiopia.)
* "Vu de loin, aux limites de l'horizon, le qobar semble disposé par
* couches, le plus souvent horizontales, à tranches nettes, sans bavures,
* et tellement denses que le soleil s'y éclipse comme derrière l'écran
* le plus opaque. Ainsi, dans Ynarya nous vîmes, le 24 janvier 1844, le
* soleil disparaître complètement derrière un banc de qobar qui devint
* ainsi visible négativement. A mesure qu'il descendait, son disque
* paraissait, au-dessous de la limite inférieure du qobar, aussi net et
* exempt de déchirures que si l'on avait enlevé d'un trait de diamant la
* moitié supérieure d'un disque de verre rouge. Cette couche de vapeurs
* sèches avait une légère réfraction de lumière rouge sur sa surface
* supérieure pendent que l'astre était caché derrière, et nous pûmes
* voir ainsi que cette surface était tant soit peu plus déchiquetée que
* la surface inférieure."
* "Le caractère le plus frappant de notre météore, outre l'énorme
* sécheresse qui l'accompagne toujours, c'est sa faculté d'éteindre
* la lumière." N.B.: Drawing shows a VERTICAL COLUMN -- cf. Livesey, 1985.
* ". . . et toutes ces couches interceptaient totalement et sans
* déchiqueture la lumière du soleil."
* Many nice accounts of phenomena over a small lake (Tana).
* The comments following on pp.303-304 by the Commission of referees say
* that d'Abbadie was from a family of the Midi, and educated in Toulouse;
* he apparently inherited wealth, which he used to support scientific
* expeditions. This connection explains his presenting the paper here, and
* his final paragraph thanking the city fathers for their support of the
* Toulouse Observatory.
* THOMAS MILNER's "Atlas" -- mostly taken from his "Gallery of Nature"
* The "Icelanders" part has changed to: "The most usual effect is an
* increase in the vertical dimensions of the objects affected, so that
* low coasts appear elevated, what seamen call looming , and sites below
* the horizon are brought into view. The Icelanders, who are familiar
* with this effect of atmospherical refraction, call it upphillingar . . . .
* "It is an old tradition, that Hvidsærk, a mountain in Greenland,
* and Sneefields, in Iceland, have both been visible at the same time
* from the middle of the intervening strait, which at the nearest point
* is about 300 miles wide. Though treated as a fable, it may be strictly
* true, owing to the effects of refraction. The last named mountain,
* Sneefields, though it is not seen under ordinary circumstances for
* more than 80 miles, has yet been often visible from the sea beyond
* the Westmanna Isles, a distance of more than 140 miles; and Scoresby
* relates having seen a part of the Greenland coast of inferior height,
* Home's Foreland 3500 feet high, when 160 miles distant." (p. 95).
* Note: "upphillingar" seems to be the correct spelling.
* A very SUCCINCT SUMMARY of all of atmospheric optics
* J. Bradford Cherriman's review article deserves to be better known!
* He covers everything: refraction, mirages, scattering, absorption,
* rainbows halos, glories and coronae. He explains superior and inferior
* mirages, and says: "To this class of phenomena belong the well-known
* Fata Morgana , the appearances seen on the sandy plains of Egypt, and
* called by the French Mirage , and the Looming occasionally seen in
* parts of Great Britain."
* N.B.: The Roy. Soc. Cat. has this under "Bradford".
* See Cherriman's entry in the Dictionary of Canadian Biography at
*
* http://www.biographi.ca/en/bio/cherriman_john_bradford_13E.html
*
* IRISH Fata Morganas, some with COLOR
* The first sentence is: "These singular illusions are termed in the
* Irish language Duna Feadhreagh , or Fairy Castles."
* After citing several rather fantastic reports, the author describes
* his own observation: ". . . in June, 1833, he himself and a party of
* friends, when standing on a rock at Portbalintrea, perceived a small
* roundish island as if in the act of emerging from the deep, at a distance
* of a mile from the shore; at first it appeared but as a green field,
* afterward it became fringed with red, yellow and blue; whilst the forms
* of trees, men and cattle rose from it slowly and successively; and these
* continued for about a quarter of an hour, distinct in their outlines,
* shape and colour; the figures, too, seemed to walk across it, or wandered
* among the trees, the ocean bathed it around, the sun shone upon it from
* above; and all was fresh, fair, and beautiful, till the sward assumed a
* shadowy form, and its various objects, mingling into one confused whole,
* passed away as strangely as they came."
* Further instances are mentioned, but do not seem to be first-person
* accounts. A few references are offered for these later examples.
* There seems to be no standard abbreviation for these Reports; see
*
* http://www.scholarly-societies.org/history/1831baas.html
*
* The full title of the volume is: Report of the twenty-second meeting of
* the British Association for the Advancement of Science; held at Belfast
* in September 1852.
* Note: these "Transactions of the Sections" are paginated separately
* from the rest of the Reports, though both are bound together. They
* are headed "Notices and Abstracts of Miscellaneous Communications to
* the Sections", and follow the first 355 pages of the volume. According
* to the Indexes that appear at the end of this section, the first part
* of the volume is "Reports on the State of Science", while the second
* is "Miscellaneous Communications to the Sections."
* Following p. 144 of this section comes yet a third, separately
* paginated, section of the volume (again starting on p.1) that lists
* "those Members of the British Association . . . to whom Copies of this
* Volume [for 1852] are supplied gratuitously . . . ." -- with separate
* lists of "Honorary Members", "Life Members", and "Annual Subscribers".
* This is followed by several un-numbered pages listing the past volumes.
* Note that the M of M`Farland is followed by a left single quote mark.
* He does not appear in any of the lists of members.
* Adolphe Ganot's famous textbook
* This went through 18 editions under Ganot himself; Hachette continued to
* produce revised editions until 1931. It was distinguished by the
* introduction of numerous woodcuts, from the 2nd (1853) edition on.
* The PALM-TREE diagram appears on p. 366: "Le mirage est une illusion
* d'optique. . . .
* "Ce phénomène a été observé dès la plus haute antiquité; mais c'est
* Monge, le premier, qui en a donné l'explication, lorsqu'il faisait
* partie de l'expédition d’Ègypte."
* The 17th ed. is at Gallica; the figure is slightly more elaborate, and
* appears on p. 473 there.
* BRAVAIS reviews mirages
* (This 53-page article is filed separately.)
*
* EARLY USE of "INFERIOR" and "SUPERIOR" mirage terminology:
* "Description du mirage ordinaire ou mirage inférieur" (p. 234)
* "Mirage inverse ou mirage supérieur" (p. 264)
*
* This is an outstanding review of the early literature, containing many
* results not re-discovered until much later. EXCELLENT INSIGHT into
* the problem, despite being confined to simple analytical cases.
* Very complete REFERENCES to the earlier literature, even mentioning
* Quintus Curtius (p.227). But he relies on secondary sources (like
* Gilbert), consistently calls Minasi "Minazi", and confuses Biot's
* publication date (1809) with the year of his observations at Dunkirk.
*
* He is very impressed with Wollaston's 1800 paper. (pp.231-232)
*
* Much discussion of the fact that the inferior mirage is usually smaller
* than the direct image (pp. 233, 241, etc.), and tentatively attributes
* it to the CURVE of the Earth: "J'ai remarqué que, lorsque l'oeil est
* près de la surface des eaux, à 1 mètre ou 2 mètres au plus de
* hauteur, les objets étant rapprochés, les deux images ne diffèrent
* pas beaucoup de l'égalité; mais que, si l'oeil est beaucoup plus
* élevé, par exemple à 10 ou 12 mètres d'elévation au-dessus du
* niveau de la couche liquide, le rétrécissement de l'image inférieure
* devient extrêmement sensible: d'après cela, il me paraît probable
* que la courbure de la terre joue un rôle assez actif dans ce
* phénomène." (p.241) [cf. Riccò et al., 1888.]
* This idea was proposed earlier by Woltman (1800).
*
* CARE in observing: "Pour bien discerner le mirage, il faut
* non-seulement une vue longue et étendue, mais savoir observer des
* détails, et avoir l'habitude de l'horizon. Aux voyageurs, aux marins,
* aux météorologistes, cet exercice est devenu familier; le reste des
* hommes s'en doute à peine; vous leur montrerez le mirage et ils ne le
* verront pas, ou ils ne verront qu'un peu de brouillard et de fumée
* à l'extrême horizon." (p.235)
*
* EFFECT of INFERIOR MIRAGE on HORIZON (WAVES):
* "L'horizon sensible de l'eau paraîtra presque toujours offrir un
* léger tremblotemont: si le mirage est fort, il sera bordé par une
* crête dentelée dont les sinuosités paraîtront sans cesse monter et
* descendre, s'effacer et reparaître." (p.235)
* How to tell REFLECTION on water from inferior mirage, p.237.
* "En général, dans le cas du mirage, le raccordement d'une ligne
* oblique avec sa symétrique située au-dessous se fait, non par un angle
* à sommet net, mais par un arc de courbe ayant son principal élément
* vertical." (p.238) [cf. Wollaston, 1803; & Gilbert's 1806 transl., Fig.6 !]
*
* OPTIMAL HEIGHT of EYE: "Il est très-probable qu'il existe une certaine
* hauteur de l'oeil pour laquelle l'angle entre l'horizon apparent et la
* ligne de partage des objets situés à une distance donnée est un
* maximum. Ce maximum, dont la hauteur doit varier avec les circonstances
* météorologiques du mirage, paraît avoir lieu pour une élévation
* de l'oeil de 1m.5 à 2m . . . ." (p. 242)
*
* He seems to be the first to see that the whole TEMPERATURE PROFILE must
* be measured, and that the thermometer must be ventilated. (pp. 242-243)
*
* Effect of UNEVEN GROUND: ". . . le mirage des plaines ne pourra jamais
* offrir une régularité aussi parfaite que le mirage des mers ou des
* lacs." (p. 244)
*
* Notices "que le niveau de la caustique ne peut jamais s'élever . . .
* au-dessus de l'horizon apparent." (p. 250) -- a hint of The Theorem.
*
* LOOMING is explained on p. 256: the ray curvature can exceed the Earth's.
* He also finds hints of the CONCAVE SURFACE and the appearance of
* "high cliffs" in Woltmann and Biot (p.257) -- i.e., the Fata Morgana.
*
* An early EXPLANATION of NEGATIVE DIP (cf. Kimmfläche, and Biot):
* the space below the level where ray has constant height "est pour
* l'observateur comme s'il n'existait pas, c'est-à-dire comme si le sol
* ou la mer s'élevaient . . . ." (p. 262)
*
* He notes de Tessan's observations of "terres qui paraissaient bordées
* d'immenses falaises" (p. 263) in the estuary at Rio de Janeiro. And
* in discussing Woltmann's observations, he says: "souvent une strie
* d'air séparait l'image renversée des objets placés au-dessous; mais le
* plus souvent, l'image et l'objet se rencontraient et se pénétraient de
* telle sorte qu'il en résultait l'apparence d'une haute falaise avec des
* stries verticales." (p. 268) [translated from p. 430 of W., (1800).]
*
* His numerical difficulties (bottom of p. 272): ". . . j'ai été arrêté
* par la difficulté de cette analyse, et surtout par la complication
* des calculs numériques."
*
* He also emphasizes the parallels between inferior and superior mirages,
* and deals with the paradox of the missing 3rd image in inferior mirages:
* "le sol interceptera les trajectoires qui la forment et fera disparaître
* l'image directe secondaire qui devrait cette fois se montrer en dessous
* de l'image renversée." (p. 274)
* "Cette non-observation de la troisième image, dans le cas du mirage
* ordinaire, ne forme donc point une objection sérieuse contre la
* théorie que nous venons d'exposer." (p. 275) Yet Wollaston has seen
* it in the lab (p. 276).
*
* ADVICE to observers: ". . . il est très-utile d'être muni d'une longue
* vue, ou à son défaut, d'une lorgnette de spectacle groissant au moins
* deux à trois fois, et que certains détails échapperaient à l'oeil
* nu qui pourront être facilement saisis par une lunette . . . ." (p. 280)
*
* The first 3 volumes of this Annuaire were bound together, with a common
* table of contents. This 4th volume is separate, with its own Introduction
* that mentions Bravais's "Note" on p. VIII. The formation of the new
* Société Météorologique is reported on p. XIII. Bravais is one of the 5
* signers of the Letter announcing this event.
*
* As usual, the Google Books scan is half useless because the plates are
* only shown folded up, and so mostly invisible.
* Gallica tries to show the plates; but the lines are too fine for the
* scanner they used, and so again are nearly useless.
* Note the Erratum on the last page, correcting the error on p. 256.
* No date is assigned to the manuscript; but as it comes toward the end of
* the collections of papers in this volume, I assume it was submitted
* late in 1852.
* Bravais's follow-up comments on his "Notice" (above)
* He begins by explaining his strategy in dealing with the mirage problem.
* Notice that he seems to prefer his "direct/inverse" terminology to the
* "inferior/superior" alternative that won out.
* After briefly summarizing his first mirage "Note", he gets into the
* horizontal-ray problem on p.56:
* "Jusqu‘ici on a fait jouer au phénomène de la réflexion
* totale des objets un grand rôle dans la théorie du mirage. Le
* redressement des trajectoires lumineuses qui, après avoir été
* plongeantes vers le sol, deviennent horizontales pendant une courte
* portion de leur trajet, et vont ensuite en s‘éloignant du sol,
* paraissait à plusieurs physiciens ne pouvoir s’expliquer que par
* un phénomène de réflexion totale. Je montrerai que les conditions
* nécessaires pour produire cette réflexion ne peuvent exister, et que
* le mirage est un simple phénomène de réfraction. M. Biot a fait
* voir que le fait du redressement s‘expliquait très—bien, dans le
* système de l‘émission. On verra qu‘on l‘explique avec la même
* facilité dans le système des ondes lumineuses, en adoptant les idées
* de Fresnel sur la vitesse de la lumière dans les différents milieux.
* 0n arrive alors à cette conséquence remarquable. que lorsqu‘un rayon
* de lumière traverse un système de couches planes et parallèles, et,
* par exemple, horizontales, dont la densité varie suivant la normale
* commune aux couches, la courbure de la trajectoire est partout égale au
* quotient de la variation du logarithme de l‘indice de réfraction, par
* la variation correspondante dans la hauteur de la couche considérée. De
* là se déduisent facilement les équations qui peuvent ensuite servir
* à expliquer les circonstances du problème."
*
* This is in the section called "Bulletin des Séances" -- the
* reports of the meetings. The date is 8 Mars 1853; Bravais presided.
* The report of this meeting begins on p. 34 and ends on p. 64.
* The volume is in two sections, separately paginated. The part with
* the meeting reports ends on p. 241; the Table of Contents is pp.239-241.
* Mostly superior mirages, with DRAWINGS; Fata Morgana mentioned
* "Few have traversed the plains of central India without being struck
* by the appearance of distant cliffs --- sometimes also of towns and
* forests, seen shortly after the rising of the sun, but which they have
* vainly looked for later in the day. I first observed this phenomenon in
* October 1829, when marching with my company from Kurnaul to Mhow in Malwa.
* Several times on reaching camp, I found it pitched in a plain, walled
* apparently to westward by lofty (See Pl. VI.) cliffs which had an inviting
* aspect. Several times I promised myself that in the afternoon I would
* pay those cliffs a visit. But, whenever I would accomplish this design,
* I found that the cliffs had entirely disappeared, and I questioned whether
* I had not been suffering some illusion of the eye or mind: for I was not
* then aware that Mirage is known in India. A residence in Malwa, where
* it is common, made me familiar with some of its phases. . . ." (pp.163-4)
* Major Abbott understands the appearances well, but not the physics
* behind them. He continues:
* "The Mirage most commonly observed in India is the effect produced upon
* distant objects, by means of a mirror, suspended with its surface
* downwards at the distance of from 60 to 230 feet from the earth. . . .
* This mirror is a stratum of dense but transparent and scarcely visible
* vapor, evolved from the dewey earth by the action of the sun's rays,
* generally about an hour or two hours after sunrise. The refractive power
* of this vapor being greater than that of the atmosphere, acts precisely
* as would a mirror of glass . . . ."
* So his "cliffs" are the striated zone of the Fata Morgana; and his
* timing is that of Angelucci's observation from Reggio. He fails to
* understand the atmospheric physics, either optically or dynamically.
* "This reflecting canopy exhibits the images of distant objects alone,
* because its substance is not sufficiently dense to repel those rays
* of light which fall upon it at any sensible angle of incidence. It is
* only when the angle of incidence is extremely small, that the ray will
* rebound from the surface of the vapor. It follows that supposing the
* strength of the illumination sufficient, the image will be distinct in
* proportion to the distance of the object." (So, unlike Monge, he does not
* think this is total reflection.)
* He does give us some further information: "The ordinary Mirage of India
* occurs at distances of from three to eight miles. But . . . the effect may
* be produced at distances so remote, as that the substance is completely
* hidden in the convexity of the earth, and only the reflected image is
* seen suspended in the air. Of such an effect the Fata Morgana are an
* instance. And the pictures of coming vessels, as seen from the Isle of
* France, are another."
* "In India, the most general appearance is that of a long range of
* cliffs standing to westward of the spectator. . . . Trees are the objects
* most commonly pictured by the Mirage. . . . But sometimes the monotonous
* aspect of the cliff is diversified and enlivened by the presence of a
* white town or of moving objects. Every stump of a tree becomes a palm or
* a column. Every little bush becomes a tall mass of foliage." (p. 165)
* "With respect to the Isle of France, the vapor hanging over the sea is
* probably more transparent and of higher elevation than that which
* overhangs the land. . . . the sails of a vessel brightly illuminated by the
* sun, might be seen at the distance of a hundred or more miles. . . . the
* reflecting canopy is not a perfect plane, but is a mirror slightly
* concave answering to the convexity of the earth. The image therefore
* would probably be magnified in the concave mirror . . . ." (p. 166)
* "The effect of mirage is greatly enhanced by the use of a telescope
* which . . . greatly increases the beauty of the exhibition." (p. 167)
* He then briefly describes seeing "another variety" of mirage, "in which
* the reflecting surface lies below the object and the spectator's eye.
* . . . The effect was precisely that produced by water upon objects standing
* beyond it, excepting that the strong undules of the vapour [sic] did not
* much disturb the accuracy of the reflection." (p. 167; cf. Büsch, 1800)
* [So he saw inferior mirages more rarely than superior mirages! And on
* the next page, he says he had not been able to study the mirage of the
* desert, which "is commonest at night in India."]
* "I have also observed upon the Nurbudda and other large rivers that,
* whereas the nearer current is too rapid and turbid to reflect the rocks
* upon its banks, the more distant current, equally rapid and equally
* turbid, presents a perfect reflection of the banks without any waving of
* outline. This may be attributable to the transparent vapour, ever hanging
* over streams, acting as a mirror to reflect surrounding objects." (But
* then he allows that it might be due to the combined reflections from wave
* crests -- cf. Budde (1885) and Venturi (1889).)
* EARLIEST WAVE-CREST THEORY?
* On p. 169, he says he has "referred to Brewster's treatise on mirage,"
* and thinks that Brewster's attribution of superior mirages to "a denser
* stratum of atmosphere" is "a mistake." "It is undoubtedly a stratum
* of vapour which forms the mirror". So he thinks his own crank theory
* explains why "the phenomenon is only or chiefly visible from the 1st to
* the 2nd or 3rd hour after sunrise and when the nights are rather chilly
* and the skies clear."
* So his observations are accurate and useful, but his theory is nonsense.
* Major James Abbott
* Long verbal descriptions of inferior mirages; no drawings
* Remarks on effects of height of eye, etc.
* From 37 m height, "l'image inférieure était moindre de moitié."
* Possible FATA MORGANA with SUPERIOR MIRAGES with a fine fold-out plate.
* A very detailed account of observations from 37 m with 40x telescope.
* DIP VARIATIONS of 4' reported.
* "Abnormal" refraction is in fact normal:
* "Ces divers effets, je les ai observés si fréquemment, qu'on pourrait
* dire que c'est l'état normal de la contrée."
* A reasonable interpretation of "FOG":
* "Ce nuage est venu du côté de la haute mer. Sa largeur est faible, sa
* teinte et sa consistance sont celles d'un nimbus. It est probablement
* l'image du sol vu de profil." (p.248)
* "Il s'annonce par une vapeur générale qui couvre le ciel à l'horizon,
* sur une hauteur d'environ 3'." (p.251)
* A "BREATHING" MIRAGE:
* ". . . montant . . . et . . . redescendant renversées : one dirait qu'il les
* aspire à son passage."
* ". . . it n'eût ondulé, au point qu'il semblait danser , selon
* l'heureuse expression de M. Humboldt."
* At one point the inverted image disappeared, leaving 2 erect ones.
* (cited by Mascart)
* EARLY MURAL MIRAGE
* "Le soubassement sud-ouest de la Bourse de Paris, que pour abréger
* j'appellerai le mur méridional, est formé d’un mur vertical en pierre
* de taille, parfaitement construit, et sans aucune partie saillante dans
* une étendue d’environ 78 mètres. Lorsque, entre midi et 3 ou 4 heures,
* ce mur est frappé parles rayons solaires, il présente le phénomène
* du mirage avec une assez grande intensité. . . .
* "Le mirage se manifeste aussi très-bien sur les murs des
* fortifications de Paris, surtout du côté du sud. . . . si l’on observe
* les images réfléchies avec une lunette, on peut voir jusqu'à des arbres
* entiers avec leurs branches et leurs feuilles. Si le prolongement de
* la muraille rencontre une route fréquentée, on distingue très-bien
* à la lunette les images réfléchies des passants, des chevaux et
* des voitures, lorsqu'ils se présentent près du prolongement du mur.
* A un degré plus ou moins intense, ces phénomènes ont lieu tous les
* jours, ou du moins toutes les fois que le soleil éclaire les murs des
* fortifications, depuis deux ou trois heures.
* "Au reste, comme il résulte des faits consignés dans ce Mémoire,
* le mirage se manifeste à Paris, dans beaucoup d’endroits, d’une
* manière permanente, l’hiver et l'été, la nuit et le jour. Lorsque le
* soleil brille avec un certain éclat, on peut l'observer très-facilement
* sur toutes les surfaces planes d’une certaine étendue exposées au
* soleil, sur les parapets des quais, sur les trottoirs, sur les marches
* des églises, etc.; mais c'est à la Bourse, je le répète, que le
* mirage se développe plus énergiquement et plus régulièrement que
* partout ailleurs."
* This is NOT the well-known astronomer with the same last name.
* The initial "E" is listed in the volume's author index.
* SUNSET MIRAGE
* "Auf einmal bemerkten wir, dass unsere Schatten, die wir vor uns liegen
* hatten, da wir ostwärts gingen, doppelt waren und zwar in der Weise,
* dass über unseren Köpfen im Schatten noch ein zweiter Kopf deutlich
* und scharf hervortrat. Ich sah mich um nach der Sonne, und
* es zeigten sich im Westen . . . zwei klare Sonnen vertikal
* übereinander. Der vertikale Abstand beider Sonnen von einander betrug
* etwas über einen Sonnendurchmesser."
* A good account of mirages seen on the Bodensee ( = Lake Constance)
* with many DRAWINGS and a good description of the DISTANCE EFFECT:
* "Ein in der Richtung nach Constanz fahrender Dampfer bot die bequemste
* Gelegenheit dar, die Erscheinung nach allen Modifikationen, welche die
* zunehmende Entfernung mit sich brachte, zu verfolgen."
* (The description is a whole page long -- too long to quote here.)
* He also notices the slight vertical compression of the inferior image,
* and mentions (but does not cite) a mural mirage "nach den Comptes rendus
* der Pariser Akademie . . . neuerdings an der südlichen sonnenerwärmten
* Aussenwand des Börsengebäudes in Paris . . . ."
* [This seems to refer to Bigourdan's report of 1855.]
*
* There is a good concluding EXPLANATION of the FANTASTIC SCENES often
* reported: "Wie ist es aber möglich, dass die Luftspiegelung Gegenstände
* darbietet, welche in der Wirklichkeit gar nicht vorhanden sind, Gebäude
* mit Kuppeln, Balkonen, Säulen, Palmenhaine, wo der enttäuschte Reisende
* nichts findet als Felsblöcke, Sandhügel und Gestrüpp? Bringen wir in
* Abzug, was auf Rechnung der Phantasie und der Vergrösserung durch die
* Fama beim Übergang der Beschreibung von Mund zu Mund, von Buch zu Buch
* kommen mag, so bleibt vielleicht folgende natürliche Auflösung des
* Zaubers. Ich sah hie und da eine rundliche Masse wie einen Baum,
* Steinhaufen oder dgl. mit ihren verkehrten Spiegelbild zu einem
* Doppelgebild zusammenfliessen, das an beiden Seiten den Anschein von
* senkrechten Wänden darbot. Hie und da zeigte sich am Seenufer ein
* steiler, senkrecht wie von Erdrissen durchstreifter Absturz, wo ich keinen
* solchen vermuthen konnte, und auch bei der nachfolgenden Betrachtung
* Nachmittags oder von einem höheren Standpunkte aus nur den schmalen Saum
* einer Kiesbank oder eines sonstigen unbewachsenen Bodens vorfand. Wie aus
* einem Felsblock dieser Art ein Gebäude, aus einem kurzen senkrechten
* Fleck eine Säule, aus Gestrüpp ein Wald werden kann, wenn der Wunsch und
* die Phantasie das ihrige dazuthun, mag einleuchten." (cf. Beauford, 1802)
* This paper makes no sense until you know that the German "geogr. Meile"
* was 1/15 of a degree, or 4 nautical miles.
* This is the only place outside of America where I have seen ' used for
* feet and " used for inches!
* A more direct account of the inferior and superior mirages than the
* following one. Good descriptions of FOG ("nuage").
* A rather tedious account of inferior mirages seen at Montpellier
* FOG : "La mer la première se couvrait de la vapeur du mirage, vapeur
* blanchâtre qui le signalait toujours."
* TURBULENCE: ". . . un fort miroitement se prononçait dans le région du
* mirage, malgré le calme qui régnait dans toute la contrée; les images
* y flottaient, comme agitées par un vent violent . . . ."
* DEMAGNIFICATION: "Cette précision des images rendait encore un autre
* service: elle permettait de voir que l'image réfléchie était d'un tiers
* au moins plus petit que l'objet." (seen from 37 m height)
* (cited by Mascart)
* Pierre-Adolphe Daguin's textbook
* A pretty thorough treatment, containing an early version of the
* "PALM-TREE" diagram -- complete with an 18th-Century French soldier
* as the observer (p. 372). [Cf. A. Ganot (1853).]
* This is the section on atmos. refr.
* The first volume appeared in 1855. A second edition came out in 1861;
* the third, in 1867; and the 4th, in 1878.
* Title page also lists Dezobry & E. Magdeleine, Paris, as publishers.
* KUMMER's paper on super-critical refraction in dense atmospheres:
* Multiple complete images of the whole sky and the whole surface of the
* planet, even for an outside observer.
* Novel treatment of the problem from a mathematical point of view;
* Kummer has fun with PDE's. Note that he correctly describes the
* multiple horizons and the apparent horizon at the top of the duct,
* when the observer is inside the duct-producing inversion, as well as
* the distorted images:
* ". . . das erste Bild [der Sonne] welches . . . zu einer sehr schmalen
* Ellipse abgeplattet erscheinen müßte . . . ."
* Available at last at
* http://bibliothek.bbaw.de/bibliothek-digital/digitalequellen/schriften#A9
* The volume for 1860 was published in 1861. Meeting date: 12. Juli
* [cf. Bouguer (1749), T. Young (1807) and J.de Graaff-Hunter (1913)]
* See also the 1863 reprint and its English translation (below).
* VERDET translates (?) Kummer's paper
* The section is headed "Mémoires sur la physique publiés a l'étranger.
* Extraits par M. Verdet." Verdet's presentation is somewhat more compact
* than Kummer's; it is not just a straight translation. In particular,
* note that Verdet defines the angle i as the local zenith distance of
* the ray, whereas Kummer uses the same symbol for its altitude (see the
* bottom of p. 498). Consequently, Verdet has sin i where Kummer has
* cos i . Similarly, Verdet's "I" is the complement of Kummer's.
* There is a typo on p. 500, where Verdet says "I" when he means Kummer's
* small quantity ε. (He was thinking of the special value of i at the
* top of the duct, which he denotes by I a page or so later on.)
* (available from Gallica)
* An exact reprint of Kummer's original paper:
* (this is the version reprinted in Kummer's collected papers, edited by
* André Weil (Springer-Verlag, Berlin, 1975) pp.337ff.)
* Mila Zinkova has discovered an English translation at
* http://www.neo-classical-physics.info/uploads/3/4/3/6/34363841/kummer_-_on_atmospheric_ray_refraction.pdf
* However, this translation is rather awkward, as the translator is not a
* physicist, and adopted peculiar terms instead of conventional terminology:
* thus we see "refraction exponent" instead of "refractive index"; "Kugel"
* is translated as "ball" rather than "sphere" or "globe"; "Luftspiegelung"
* is literally rendered as "air reflection" instead of "mirage"; and the
* niceties of German syntax sometimes become sheer nonsense in English.
* Hunt's observation of an OMEGA MOONRISE in Key West
* "When becalmed in a beautiful evening between the Reef and the Key, the
* water being very tranquil, I saw the moon rise over the sea with some
* interesting appearances. The long reflection of the emergent disc on the
* water was well defined, and seemed to be a part of the moon itself. As
* the under semicircle of the disc began to rise above the water, there was
* an appearance of drawing in at the sides of the combined luminous figure.
* As this seeming contraction progressed, the outline showed a curved
* figure, like that made by water in raising a cohering disc from its
* surface. There was no cusp point between the disc and the
* disc-reflection, but a seemingly distinct curve, concave outwards. As
* the disc rose above the water, this curve opened, and a broad connecting
* column seemed to bind the disc and its reflection, just like a coherent
* water column between the lifted disc and the level water surface.
* Instantly this seeming column parted as if broken, when the moon was seen
* to be distinctly above the water by about a fourth of its diameter, as
* nearly as I could estimate. The sudden shock of rupture appeared
* perfectly distinct, and the semblance of a material connection between the
* disc and reflection was perfect, both before and at the instant of visible
* separation. This observation has interest in its relation to the contact
* phenomena of eclipses." So he mis-interpreted what he saw, in spite of
* very accurately recording the details.
* This is a short numbered section at the end of the longer paper called
* "Key West Physical Notes". Am.J.Sci. was also known as "Silliman's
* Journal".
* A paragraph on the mirages in the Rio de la Plata
* This is a derivative work "compiled by Staff Commander James Penn, R.N."
* and "Published by order of the Lords Commissioners of the Admiralty"
* But the Advertisement that follows the title page is signed by "G.H.R,"
* at the Hydrographic Office, Admiralty, London. It says "The Rio de la
* Plata is from the surveys of Admirals FitzRoy and Suliva, Commander
* Sidney, the French charts of 1833, and the Spanish of 1837, with also
* many additions and corrections by M. Mouchez."
* The actual paragraph, headed "Mirage or Refraction", says:
* "In the Rio de la Plata there is a great deal of refraction, and
* more so in the tributary rivers. It often happens that objects above
* the visible horizon disappear; others under the horizon rise and are
* clearly seen at great distances. At Buenos Ayres the cerros de San
* Juan, under the horizon, on the Oriental coast, a distance of 36 miles,
* are sometimes seen. When this is the case the atmosphere is extremely
* clear, and it is a most certain sign of bad weather."
* [Here a footnote adds: "Colonia lighthouse, and vessels at anchor there,
* were plainly seen by the naked eye, at a distance of 30 miles. ---
* R. Cook, master, H.M.S. Stromboli , July 1862."]
* "This extraordinary refraction not only takes place near the horizon
* but also many degrees above it. E. Mouchez, capitaine de frégate,
* gives an instance of a fog rising during the time he was taking
* observations, which hid the sun but slightly, leaving the limbs clearly
* visible. In calculating the hour angles and comparing the different
* series, it was found that the refraction had regularly increased with
* the fog, and that at the last observation, when the altitude was 31°,
* it was higher by 1'25" than that given by the tables."
* Obviously this is an error in the dip, not the refraction.
* Available at Google Books.
* C. T. Ramage's report of FATA MORGANA in Apulia
* "In travelling over the Japygian peninsula, . . . I heard the natives
* speak of what they called “Mutate,” and on questioning them as to
* what they meant, I found that this was only another name for what is
* known as the “Fata Morgana.” At Nardo and Galateo, and more
* particularly at Manduria, they assured me that at dawn, when the
* atmosphere is perfectly calm, or when a “scirocco” is just beginning
* to blow, the appearances at times are very remarkable, exhibiting,
* if we can believe them, beautiful representations of castles, plains
* with cattle and flocks, men on horseback, and, what must be striking,
* the edges of the figures are often fringed with the prismatic colours."
* The mention of DISPERSION in mirages is unusual; cf. Minasi. But
* as the enumeration of details is close to Minasi's, I wonder if this
* may all be taken from his account. Ramage cites Antonio de Ferrariis
* Galatei De Situ Japygiae (1727). He then adds:
* "I have observed in another part of Italy some approach to the
* “mirage” which is here described. At early dawn, on my way through
* the Caudine Forks towards Benevento, thick mists rested on the lower
* valleys; as the sun rose and the mist began to be dissipated, the villages
* seemed to be raised by the refracted light into the heavens." This
* may be an observation of the concave appearance of the surface.
* Cited by Talman (1912).
* John Parnell's MULTIPLE-IMAGE MIRAGES at Folkestone, 13 April (1869)
* FOG: "During the morning, and up to 2 o'clock P.M., a dense fog had hung
* over the sea; but apparently it was not very deep, as the sun's rays
* penetrated it pretty freely. At the hour above mentioned the fog opened
* towards the S.E., disclosing the cliffs on the French coast; and in the
* course of a few minutes the fog had disappeared, leaving the atmosphere in
* a state of unusual transparency. The French cliffs were apparently so
* lofty and with every indentation so clearly visible, that one might easily
* have imagined that they were but ten miles distant."
* CONCAVE SURFACE: "The French coast could be seen from near Calais
* towards the E. to far away and many miles beyond Boulogne towards the
* S.W., the land in the latter direction being ordinarily invisible, as it
* is situated below the horizon. Immediately under the erect image of the
* coast was an inverted one, of about double the height of the former.
* The lighthouse at Cape Gris Nez gave five images in a vertical line: --
* the lowest erect but somewhat magnified; above that and separated from
* it a pair of images of the centre and highest portion of the building
* only, one erect and the other inverted; and over these another pair, the
* inverted image being like the former one, but the erect image showing the
* whole building."
* These are often supposed to be the first observations of more than 3
* images, though Kelly saw 5. However, Parnell reports seeing both 7 and
* 9 : ". . . some fishing-luggers were observed hull down, so that the
* position of the horizon could be ascertained . . . but over these were pairs
* of images of vessels which ordinarily would have been invisible. In some
* instances three and even four pairs could be observed placed in a vertical
* line, the lower image in each pair being inverted. With the exception of
* the uppermost pair, the images seemed to represent the maintopgallant
* sail only, and that considerably elongated; but the highest erect image
* showed the mizzen- and the fore masts and the jib, but in no instance
* could the hulls be seen. In all cases the inverted images were of about
* twice the height of the erect. Soon after 3 o'clock vessels between the
* observer and the horizon began to be affected. The Varne light-ship,
* which is about 8 1/2 miles from the English coast, had her mast-flagstaff
* and stanchions elongated to some three times their proper length: this
* effect lasted for about ten minutes, when they shrank to less than half
* their usual size, and the hull began to rise till it was nearly as high as
* it was long, and formed a most conspicuous object even to the naked eye.
* I then looked towards Dover: the pier seemed completely disorganized;
* it appeared to be divided in half longitudinally, with the sea in the
* midst, and the stone coping moved as if huge waves were agitating it. A
* steam-boat entering Dover harbour was shrunk to less than half her proper
* vertical dimensions, but elongated horizontally. Captain Paull, of the
* S.E.R. steam-boat 'Napoleon III.,' crossed the Channel between the hours
* of 2 and 4; and he told me that he saw Beachy Head during the passage, a
* circumstance which had never previously occurred during the many years
* that he has been on the Folkestone and Boulogne route."
*
* ". . . wind S.W., very light at 2 o'clock and dropping to a calm . . . ."
* "The place of observation was about 30 feet above high-water mark."
* Observations made "through a small telescope with a 25-power".
*
* Cited by Garbasso (1907). Cf. the similar report of Latham (1798).
* Available at Google Books
* JANSSEN's first mirage report, followed by Silbermann's comment
* Janssen calls it "mirage inverse qu'il a eu occasion d'observer sur
* la mer Rouge, au moment du soleil levant. Ce phénomène est dû à
* l'influence des côtes élevées qui bordent la mer. Il résulte de
* cette situation qu'au moment où se produit le phénomène observé, la
* température maximum se trouve à une assez grande hauteur au-dessus des
* eaux ; c'est seulement à partir de ce niveau qu'elle décroît
* lorsqu'on s'élève. Ce mode de distribution des températures de l'air
* est très-différent de celui qui a lieu dans une plaine unie ; il
* explique nettement et dans tous ses détails la production du mirage
* inverse au lieu du mirage direct."
* Evidently, this is a superior mirage; unfortunately, no detail is given.
* (For more of his Red-Sea sunset observations, see his 1874 paper.)
* Août 1870, No. 8
* Silbermann's comment on Janssen's mirage report
* (This is the dog-like-a-fish report.)
* "M. Silbermann . . . signale certains phénomènes curieux que l'on peut
* observer à Paris même, dans tous les points où les couches d'air
* voisines du sol peuvent être échauffées exceptionnellement sur de
* grandes étendues. Ce cas se présente assez souvent en été sur la
* place de la Concorde pour un observateur qui place ses yeux tout près
* du sol."
* Then follows a direct quote from Silbermann:
* «Si un chien passe sur le trottoir à une centaine de mètres, ses
* pattes plongeant au-dessous de la couche d'air qui produit le mirage,
* les parties supérieurs de l'animal sont réfléchies en dessous de
* cette couche. Elles offrent alors l'aspect d'une espèce de poisson
* fantastique qui semble nager à la surface du sol.»
* Août 1870, No. 8
* FLAMMARION quotes DIODORUS SICULUS (but gives no detailed reference)
* "An extraordinary phenomenon occurs in Africa at certain periods,
* especially in calm weather; the air becomes filled with images of all
* sorts of animals, some motionless, others floating in the air; now they
* seem running away, now pursuing; they are all of enormous proportions, and
* this spectacle fills with terror and awe those who are not accustomed to
* it. . . . Strangers not used to this extraordinary phenomenon are seized
* with fear; but the inhabitants, who are in the habit of seeing it, take no
* particular notice of it." (p.149)
* "Certain physical philosophers attempt to explain the true causes of
* this phenomenon, which seems extraordinary and fabulous. They say that
* there is no wind, or scarcely any, in this country. The masses of
* condensed air produce in Libya what the clouds sometimes produce with us
* on rainy days, viz., images of all shapes rising on every side in the
* air."
* On the next page, he drops a tantalizing hint:
* "This same phenomenon (of which Quintus Curtius has also spoken) has
* long been remarked by the Arabs, and it is often discussed in the
* treatises of Oriental writers."
* Flammarion has found Büsch's work, but not Gruber's; so he thinks
* Monge was the first to explain it. [Thus, the source of that error.]
* Joseph David Everett's review article in Nature
* This appears to be an exact reprint of his Belfast lecture in the
* "MIRAGE THEORY" file.
* "Another class of appearances are known (especially among nautical men)
* under the name of looming . Distant objects are said to loom when they
* appear abnormally elevated above their true positions. This abnormal
* elevation not unfrequently brings into view objects which in ordinary
* circumstances are beyond the horizon. It is also frequently accompanied
* by an appearance of abnormal proximity (though this may perhaps be rather
* a subjective inference from the unusual elevation and clear visibility
* of the objects than a separate optical characteristic), and it is further
* accompanied in many, though not in all cases, by a vertical magnification,
* the heights of objects being many times magnified in comparison with
* their horizontal breadths, so as to produce an appearance resembling
* spires, pinnacles, columns, or basaltic cliffs."
* "In rare instances, two or even three of these images are seen one
* above another, vertically over the real object; but these multiple images
* are usually too small to be seen without the aid of a telescope -- the
* objects whose images they are being so distant as to appear mere specks
* to the naked eye." (p. 49)
* He then recommends Scoresby's accounts in his "Greenland" and
* "Arctic Regions"; and quotes from Latham's (1798) account of looming
* seen at Hastings.
* "The circumstance which it is most important to know . . . in order
* to predict the degree of curvature, is the rate at which the temperature
* changes with height." (p. 50)
* "An increase of temperature upwards, at the rate of about
* one-sixteenth of a degree Fahr. per foot, would make the curvature of
* rays equal to that of the earth, so that a ray might encircle the globe.
* . . . The visible effect is precisely the same as if the convexity of the
* surface of the earth were diminished. And not only will objects which
* were previously beyond the horizon be brought into view, but objects
* which were previously visible near the horizon will become plainer,
* inasmuch as the rays by which they are seen will not pass so close to
* the intervening surface as before, but will traverse a higher portion
* of the air, which is less liable to be obscured by impurities." (p. 51)
* He then considers a parabolic temperature profile, so that "A pencil
* of rays diverging . . . from a point . . . will thus converge accurately
* to another point. . . . Such a pair of points may be called principal
* conjugate foci." (p. 51)
* ALTERNATION of erect/inverted images:
* "As every point on the surface of an object will thus have its
* conjugates, we shall have a succession of images of the object. The first
* image will be upside down, the second erect, and so on alternately.
* They will be what are technically called `real' images . . . ." (p. 52)
* He ends this part by pointing out the astigmatism of the images.
* On p. 69, he quotes (in translation) from Monge, and adds:
* "The only objection which I think can be taken to this explanation
* of Monge, is that it seems to imply not a curvature, but an angle,
* in the course of the rays, just as in the case of what is called
* total internal reflection at the bounding surface of a piece of glass
* when the angle of incidence exceeds the critical angle.
* "Now, the formation of an angle (even a very obtuse angle) in a ray
* would require a perfectly sharp transition from one degree of density to
* another, instead of the gradual transitions which are more in accordance
* with our knowledge of the properties of air."
* "As to the propriety of applying the name reflection to an action
* such as that . . . , it is perhaps just as proper as the application of
* the name refraction to the bending of rays which takes place in the
* atmosphere . . . ." (pp. 69-70)
* On p. 71, he repeats Wollaston's experiment; but "a much finer
* effect is obtained in the arrangement . . . in which three liquids are
* employed, the middle one having the highest index of refraction, while
* its specific gravity is intermediate between those of the other two.
* The three liquids are -- (1) A strong solution of alum at the bottom;
* (2) pure water at the top; (3) Scotch whiskey mixed with enough sugar
* to make its specific gravity intermediate between those of the other
* two liquids. It is introduced last by means of a pipette."
* "The arrangement of three liquids just described, which was suggested
* to me by Prof. Clerk-Maxwell, is extremely effective, but requires much
* delicacy in its preparation to ensure success."
* "With the two-liquid arrangement I have obtained three spectra,
* the middle one inverted, by employing as object a horizontal slit in the
* shutter of a dark room; and very brilliant colour effects were obtained
* by bringing the eye to the conjugate focus of the slit."
*
* "a Paper read by Prof. J. D. Everett, M.A., D.C.L., before the
* Belfast Natural History and Philosophical Society"
* In the Nov. 19 and 26 issues.
* Cited by Humphreys (1919, et seq.) and Wood (1899).
* The English version of Janssen's "mirage at sea" note
* As it is very short, I quote it completely here:
* "Many facts relating to the phenomena of mirages at sea are already
* known; but the author has paid great attention to these appearances in
* all his voyages since 1868, and has made some remarkable observations on
* mirage, especially at sunrise and sunset. He has established: -- 1.
* That the mirage is nearly constant at the surface of the sea. 2. That
* the appearances can be explained by assuming the existence of a plane of
* total reflection, situated at a certain height above the sea. 3. That
* the phenomena are due to the thermic and hygrometric action of the sea
* upon the neighbouring atmospheric strata. 4. That there exist at sea
* direct, inverse, lateral, and other mirages. 5. That these phenomena
* have a very general influence upon the apparent height of the
* sea-horizon, which is sometimes lowered, sometimes raised.
* "This variation of the apparent horizon is very important to take
* into account, if we consider the use made of the horizon in nautical
* astronomy."
*
* Note the considerable differences between this and the French version.
* Here we have "a certain height" instead of a variable distance of the
* reflecting layer above the sea; here we have both thermal and
* hygrometric effects, there just thermal; here we have lateral mirage as
* well as direct and inverse. And here, the 1868 trip is made explicit.
*
* As this was given at the Bristol meeting in August, 1875, it seems to
* pre-date the French abstract -- which may explain the disappearance of
* "lateral mirage" in the latter (below).
* [Thanks to Madame Françoise Launay for information about the date.]
* Jules Janssen's French summary of mirages at sea
* "D'après mes observations, qui embrassent plusieurs années déjà,
* le mirage en mer est très-fréquent, même dans les mers
* septentrionales. Dans le golfe de Siam et dans le mer Rouge
* [-- remember he observed the 1868 eclipse in India --], j'ai observé
* des cas très-remarquables de mirage direct et inverse . Les
* apparences observées, soit sur le Soleil levant et couchant [-- so no
* wonder Fisher was interested in this work! --], soit sur les objets
* situés à l'horizon, conduisent à admettre un plan de réflexion
* totale situé à une distance variable de la mer. La cause de ces
* effets de mirage et de réfractions anomales réside dans l'action
* thermique de la mer sur les couches atmosphériques voisines. Une des
* conséquences les plus importantes de ces études, c'est qu'elles
* conduisent à reconnaître que le niveau apparent de l'horizon de la mer
* est affecté d'une manière très-notable par ces effets optiques et
* qu'il y aura en tenir compte quand on prendra (pour des mesures
* soignées) la hauteur d'un astre par le moyen de l'horizon de la mer.
* Je construis un instrument pour donner la correction."
*
* It is almost inconceivable that Janssen had not also seen numerous
* green flashes on these trips, though he says nothing of them here. And
* it is said that Janssen was consulted by Jules Verne for technical
* information while Verne was writing "From the Earth to the Moon." Could
* Janssen be the source from which Verne learned about green flashes?
*
* I have no volume number for this.
* very brief mention of Janssen's mirage-at-sea observations
* "En outre, . . . études sur le mirage en mer, études qui
* conduisent à l'explication des variations apparentes de la hauteur de
* l'horizon marin, et fourniront des bases plus sûres à l'Astronomie
* nautique." (p. 584)
* [followed by a detailed description of the Revolver photographique ,
* with detailed plates.]
*
* The Annuaire turns out to be a sort of French World Almanac ,
* rather than another Connaissance des Temps . There are tables
* of foreign exchange rates, conversions between decimeters and
* feet/inches/lines, densities and refractive indices of various
* materials, a list of the principal cities of the world, the areas
* and populations of the Arrondissements of France, etc., etc.
*
* Reprinted in Janssen's collected works, Tome I, pp.329-332; see p.332.
* Prof. PRESTEL's mirage review, with many ILLUSTRATIONS
* It includes his own observation of a superior mirage at Borkum.
* Fig. 9 shows superior mirages, and is captioned "Das Seegesicht".
* This is almost surely Michael August Friedrich Prestel (1809-1880),
* who was Prof. of Mathematics and Natural Science at the Gymnasium at
* Emden, and part-time instructor at the Trade- and Navigation School.
* He wrote numerous papers, primarily on meteorology and related
* matters, and many popular articles, according to Pogg.
* A note on the first page indicates that earlier installments were
* in Nr. 1760 and 1761, March, 1877.
* abstract of the later Phil. Trans. paper, with comments by Everett
* O'C #136a
* vicious, nit-picking attack on Vince
* USEFUL REVIEW of HISTORY, including BIOT's book, and WOLLASTON.
* TAIT explains that VINCE's drawings were only schematic;
* "Scoresby . . . has given numerous careful drawings of these most singular
* appearances. The explanatory text is also peculiarly full and clear,
* giving all that a careful observer could have been expected to record. It
* is otherwise with the descriptions and illustrations in Vince's paper . . . .
* In fact the latter are obviously not meant as drawings of what was seen;
* but as diagrams which exhibit merely the general features, . . . -- the
* details being filled in at the option of the engraver. That such was the
* view taken by Brewster, is obvious from the illustrations in his Optics
* . . . ."
* clearer account of his mirage theory than in the Trans.Roy.Soc.Edinburgh
* O'C #137
* TAIT's full paper at last
* ". . . I do not think that Wollaston's square bottle with two
* inter-diffusing liquids presents a fair analogy." [p. 552]
* An implied DEFINITION: ". . . only one image: -- not, of course, in the
* true direction of the object: -- but erect, and therefore not properly
* coming under the designation of `mirage.'" [p. 559]
* He also notes that "although aqueous vapour diminishes the refractive
* index of air, the practical effect is so minute at its utmost that we
* neglect it." [p. 564]
* He observes directly a phenomenon closely related to GREEN FLASHes, but
* fails to make the connection: "The middle image . . . coincides with the
* upper image when the eye, gradually moved downwards, reaches the line DB.
* When they meet, both become blue and then disappear by moving the eye
* farther down." [p. 571]
* "It is much to be regretted that Vince's description, like his drawings,
* is of the very roughest character." [p. 576]
* Tait foresees the multiply-LAYERED STRUCTURE that is so common with
* inversions: ". . . when a trough, in which brine has been diffusing for
* some time into water, is suddenly and roughly stirred for a short period,
* it settles in a few minutes into a large number of strata of different
* densities. Something similar must hold in the case of air irregularly
* heated . . . . In the absence of wind such strata, once formed, would last
* for a long time, in consequence of the very small thermal conductivity of
* air." Then he cites Tissandier's observation of a mirage from a balloon,
* mentioned in Glaisher's Travels in the Air , p.297. "This, of course,
* proves the existence, at a great elevation, of a stratum in which there
* was a comparatively rapid diminution of refractive index with increasing
* height." [pp. 576-577] Cf. Gossard et al. (1985).
* Finally, he points out an essential difference between inferior and
* superior mirages [which an astronomer would call SEEING]. After quoting
* Scoresby's observation of his father's ship beyond the horizon, where the
* miraged image "was so extremely well defined, that when examined with a
* telescope by Dollond, I could distinguish every sail . . . ", Tait adds,
* "It seems hard to reconcile the clearness of definition in this case with
* any other than a stable state of equilibrium of a transition stratum. The
* mirage of the desert, where the equilibrium is essentially unstable, is
* always exceedingly unsteady."
* At the very end, he admits that most of his results were already found
* by Biot, in his mirage monograph.
* O'Connell #136b
* Jules JANSSEN claims to photograph mirages in Algeria
* Possibly EARLIEST PHOTOGRAPH of mirages? (But not published.)
* Mostly about the transit of Venus; but in the last paragraph:
* "Enfin j'ai pu faire quelques études sur le mirage, dont les
* manifestations sont presque permanentes en ces régions. J'ai pu même
* faire photographier plusieurs de ces manifestations, et constater que
* les causes de ces phénomènes, dans les cas les plus nombreux, sont
* tout autres que celles admises généralement."
* EARLIEST demonstration of "Fraser's THEOREM" by Edward Sang; he thought
* Vince had seen "a sloop floating on a calm sea with its shadow in the
* water" and imagined the rest.
* FLAT EARTH:
* FIRST derivation of flat-Earth model: "No sun, moon, or star could have
* been seen at a lower altitude than 1° 22'. All light reaching the
* eye from a lower elevation must have come from some terrestrial
* object. . . ." [But see Biot's 1809 monograph for the magic angle!]
* "Inverted images, then, can only be seen when the air is in an unusual
* condition; there must be unusually light air above. Now, in these, as in
* all investigations on the subject, the air is assumed to be disposed in
* horizontal layers, each of uniform density. . . . The absolute need for
* smoothness of arrangement may easily be illustrated: -- the sun's light is
* certainly reflected from the surface of the sea; yet we do not see an
* image of the sun in the water; we see only a confused brightness."
* Earliest crude OMEGA drawing after Joule's? (cf. Fig. 7)
* An unclassifiable paper, but put here because it deals with the inferior
* mirage at sea. Like Maltézos, Budde discovers the mirage on his own;
* but, unaccountably, he discounts it as mirage because ``wenn über dem
* Meer eine spiegelnde Luftschicht vorhanden wäre, die bis a b Fig. 2
* reichte, so würde der Beobachter unter 5m Höhe unter ihr stehen, könnte
* also, wie leicht zu sehen, nicht das Bild Fig. 2 etc. erhalten." (p.358)
* (I.e., he assumes here that the angular difference between the apparent
* horizon and the vanishing line corresponds to the linear height of the
* mirage reflection above the sea surface.) Nevertheless, he recognizes
* that the inverted image is a "reflection", so he attributes it to the
* sea surface -- much like Venturi's 1889 wave-crest model. This leads
* him to the (correct) conclusion that the apparent horizon is depressed
* and nearer than the geometric one; but he then fails to see that this
* invalidates his reason for rejecting the mirage as the cause.
* I could as well have filed it in the Colton or Ricco files, or under Dip,
* or even with the Floor papers . . . .
* (reprinted in Naturwiss. Rundschau 1, 13 (1886).)
* An implausible "distant city" mirage
* ". . . un curieux mirage qui . . . a rendu visible toute la ville de
* Saint-Pétersbourg, qui est située à 180 kilometres de Merexull."
* Possible Biblical mirages: "AEROMANCIE" and aerial INFANTRY
* In the Hungarian plains, a mirage in which
* ". . . on voyait distinctement de nombreuses divisions d'infanterie . . . ."
* "La tradition nous offre des exemples nombreux de ces visions que les
* anciens appelaient l'aéromancie; le spectacle en devient général
* quand le système nerveux des populations se trouve modifié à la suite
* d'événements de la nature de ceux qui y avaient préparé les Hongrois."
* "On trouve au Livre VII, Chapitre XII, de la Guerre des juifs , par
* Josephe:
* « Pendant tout le cours de cette guerre, des armées qui manoeuvraient
* et formaient des sièges apparurent dans l'air. »
* "Au Livre II des Macchabées , Chapitre VII:
* « Avant que Jérusalem fût pillée une seconde fois par Antiochus,
* tous les habitants de cette ville purent voir dans l'air, pendant
* quarante jours, des chevaliers richement vêtus et des cohortes armées
* de piques; on voyait leurs mouvements, celui de leurs boucliers et une
* grêle de traits lancés de part et d'autre. »"
* [These citations are nonsense. The first may be Book VI, Ch. V, sect. 3;
* there is no Ch. XII in Book VII. See Whiston's translation of
* Flavius Josephus. The second is certainly Ch. V, not Ch. VII. ]
* After citing some more recent examples of aerial infantry seen during
* or just before wars, he says:
* "L'énumération de faits similaires pourrait fournir la matière de
* plusiers volumes. . . .
* "Ajoutons qu'il y faut faire beaucoup la part de l'imagination. Mais
* peut-être, à notre époque surtout, l'imagination n'est-elle pas seule
* en jeu. Le mirage (?) observé cet été in Hongrie est bien bizarre."
* Cf. the final remarks of William Beauford (1802).
* [ Presumably, this is Flammarion. ]
* DARK BANDING, or SKY? DOUBLE SUPERIOR MIRAGE
* "The land seen just above the lines (α) and (β) was paler than
* that seen just below these lines."
* Fringes shown experimentally in mirages -- cf. Raman's papers
* The Eiffel tower reflection (cf. Tissandier's 1890 review)
* Letter from Charles-Henri Martin to Flammarion, referring to his book
* "l'Atmosphere". The engraving is evidently from the description, not
* from observation. Probably not a mirage. In the Feb.,1890, issue.
* Janssen's mirage photography in Algeria (continued); cf. his 1883 note
* "Un autre objet intéressant a été l'obtention, par la Photographie,
* des images des phénomènes si varie's et si curieux du mirage dans les
* régions des grands chotts qui se trouvent entre le Souf et Biskra, le
* chott Melrir, Merouan, etc. La Photographie permettra de discuter, sur
* documents certains et mesurables, les conditions qui président à la
* production de ces singuliers phénomènes dont les apparences et les
* causes sont beaucoup plus multiples qu'on ne le croit."
* (Cf. his 1892 paper for more details.)
* This is reprinted in Janssen's collected works, Tome II, pp.187-188;
* but the initial page is given incorrectly there as 1067.
* It is the same expedition on which the "Janssen bands" were
* investigated.
* Unfortunately, the photographs appear to have been lost; neither
* the Academy of Sciences nor the Institute has them today.
* "The mirage of the reflection of the sun in the sea was, when seen
* through a glass, especially beautiful. It resembled a glorious cataract
* of golden water." (cf. Pekka's photo!)
* W. M. Davis's Harvard mural mirage
* On a NNW-SSE brick wall about 3 pm, Feb.10
* [This is evidently the same William Morris Davis whose paper on
* rainfall appears in the proceedings of the New England Meteorological
* Society on p. 493. He is given as "Prof. W. M. Davis" on p. 481.]
* ". . . the sunshine was strong enough by noon to melt the snow and ice on
* the streets."
* "On looking closely, I found that when my eye approached within about
* an inch of the plane of the wall, the further extension of the wall
* disappeared, and was replaced by a reflection of distant objects a little
* to the west of its line. . . . The reflection repeated all the familiar
* forms seen over the surface of the sea, when cold winds blow from the
* land over its warmer waters. . . . Effects of this kind must be common,
* for on the day in question, all the conditions were such as might easily
* occur again."
* Available at Google Books.
* The volume spans 1891-1892. This is No. 11, dated March, 1892.
* The journal was published in Ann Arbor, Mich.
* Janssen's mirages in some detail! A good OMEGA described
* The first (p. D.9) is a good description of a sunrise of Fisher's type A
* seen in the Gulf of Siam in 1874, en route to Japan for the Venus
* transit. There is no mention of a green flash: "Le lever a débuté par
* un point brillant, lequel, circonstance remarquable, se montrait non pas
* sur la ligne d'horizon de la mer, mais à quelques minutes d'arc
* au-dessus." Then comes the Omega stage: "Puis l'image solaire
* présente, à la hauteur où tout à l'heure le Soleil commençait à
* poindre, un étranglement qui va en ce rétrécissant de plus en plus,
* et l'image ronde ordinaire se dégage enfin.
* "Mais cette image est toujours accompagnée au-dessous d'elle d'une
* portion de disque qui s'en sépare et s'enfonce de plus en plus dans la
* mer pour disparaître enfin, laissant le disque supérieur dans les
* conditions ordinaires." (But he thinks it is due more to water vapor
* than to temperature.)
* This is evidently the observation Fisher (1921) tried to find, but
* without success.
* The mirage photographed in Algeria is also described (p. D.10):
* "En regardant cette photographie, on dirait qu'on a sous les yeux la
* vue d'une plage de la Manche avec ses dunes, ses eaux basses et son
* horizon de mer. Quand j'étais en face du chott, l'illusion était si
* complète que, malgré ma connaissance de la véritable nature du
* phénomène, des doutes traversaient encore mon esprit. Il était alors
* 5h du soir, le Soleil allait se coucher; toute cette plage avait une
* belle couleur bleue et un petit tremblement, qui faisait comme
* frissonner ces eaux, ajoutait encore à l'illusion.
* "Tout à coup, quand le Soleil eut disparu derrière l'horizon, la
* scène changea brusquement, et, à cette scène d'une belle plage
* maritime succéda celle d'une solitude glacée. Le tableau riant d'une
* rive méditerranéenne avait été subitement remplacé par celui d'un
* paysage d'hiver en Sibérie.
* "J'ai analysé les causes de ce curieux phénomène, mais cette
* discussion serait déplacée ici . . . ."
* His contribution is Appendix D of this volume, which also contains a
* report by rear-admiral Mouchez on the progress of the Carte du Ciel.
*
* The passage of interest here appears on pp. 265-266 of Tome II of
* Janssen's collected works. It says there that parts of the paper were
* also reprinted in pp. 92-111 of Janssen's Lectures Académiques (1903)
* but this seems not to include the interesting mirage observations.
* Applications of mirage theory to study interdiffusion of liquids,
* and corresponding laboratory simulations of mirages
* COLTON's street mirage in D.C.
* "On June 25, at about 4 P.M. . . . "
* "I infer that the mirage may not infrequently be seen over pavements
* or other surfaces of sufficient heat-absorbing capacity."
* Useless; but noted because of Colton's 1895 sunset observations.
* Available at Google Books.
* No.5, Sept. 1892; now published in Boston, Mass. -- see Editorial, p. 98
* DELEBECQUE's first Fata Morgana note
* Cited and partly quoted by Forel (1895), p. 557
* The BNF says the date is 15 Mars 1892; I have not seen it yet.
* According to Rev. Sci., this was reprinted by Ciel et Terre in 16 Sept. 1892.
* Their copy, titled "La « fata morgana », is on p. 478 of the 1892 volume.
* GOOD REVIEW of earlier mirage simulations and theory [FILED SEPARATELY]
* "Die Darstellung dieser Sachlage ist in keiner Weise neu,
* doch wohl wenig bekannt."
* Comments on Biot's theory
* EARLY mention of modeling the SETTING SUN
* Metrologist Charles-Edouard Guillaume was the inventor of Invar, and
* received the Nobel Prize in physics in 1920 for his work.
* He says Kummer first predicted a ray encircling a planet.
* [No mention of Bouguer, though.]
* "L'étude de la marche curviligne des rayons, fort intéressant en
* elle-même, devient très importante lorsqu'on l'applique aux phénomènes
* naturels. La reproduction des formes du soleil couchant offre un exemple
* d'une imitation de cette sorte. Nous pouvons, à volonté, imiter le
* phénomène normal que l'on observe chaque soir en plaine ou au bord de la
* mer, ou bien ces apparences exagérées, qui témoignent d'un équilibre
* particulier des couches d'air, ou même produire des déformations plus
* grandes que celles observées."
* This is the last volume of the old BSAF before it merged with
* l'Astronomie.
* A general introductory discussion of atmospheric optics, including
* rainbows, halos, scintillation, blue sky, refraction, (including mirages).
* The figure from Müller's "Kosmische Physik" was recently reproduced in
* *color* by Vollmer & Tammer (Appl.Opt.37,1557 (1998)).
* Note that volumes and years of H&E don't match up.
* Warren Upham's mirages on the Minnesota/North Dakota border
* "In crossing the vast plain of the Red River Valley on clear days the
* higher land at its sides and the groves along its rivers are first seen
* in the distance as if their upper edges were raised a little above the
* horizon, with a very narrow strip of sky below. The first appearance
* of the tree tops thus somewhat resembles that of dense flocks of birds
* flying very low several miles away. By rising a few feet, as from the
* ground to a wagon, or by nearer approach, the outlines become clearly
* defined as a grove, with a mere line of sky beneath it. This mirage is
* more or less observable on the valley plain nearly every sunshiny day of
* the spring, summer, and autumn months, especially during the forenoon,
* when the lowest stratum of the air, touching the surface of the ground,
* becomes heated sooner than the strata above it.
* "A more complex and astonishing effect of mirage is often seen
* from the somewhat higher land that forms the slopes on either side of
* the plain. There, in looking across the flat valley a half hour to two
* hours after sunrise of a hot day following a cool night, the groves and
* houses, villages and grain elevators, loom up to twice or thrice their
* true height, and places ordinarily hidden from sight by the earth's
* curvature are brought into view. Occasionally, too, these objects,
* as trees and houses, are seen double, being repeated in an inverted
* position close above their real places, from which they are separated
* by a very narrow, fog-like belt. In its most perfect development the
* mirage shows the true upper and topsy-turvy portion of the view quite
* as distinctly as the lower and true portion; and the two are separated,
* when seen from land about a hundred feet above the plain, by an apparent
* vertical distance of 75 or 100 feet for objects at a distance of 6
* or 8 miles, and 300 to 500 feet if the view is 15 to 20 miles away.
* Immediately above the inverted images there runs a level false horizon,
* which rises slightly as the view grows less distinct, until, as it fades
* and vanishes, the inverted groves, lone trees, church spires, elevators,
* and houses at last resemble rags and tatters hung along a taut line."
* So, here we have first a nice account of the HEIGHT and DISTANCE
* dependences of the inferior mirage; then a FOG report connected with
* the superior mirage.
* Quoted (but not cited) in Frazer (1929).
* More FATA MORGANA studies, following FOREL
* His telescopic observations indicate that the F.M. is not a simple
* vertical elongation, but a stack of direct and reversed images: "J'en ai
* compté jusqu'à cinq. Comme ces images sont, en général, très
* rapprochées; que parfois même elles empiètent l'une sur l'autre, il est
* très difficile de les séparer à l'œil nu, et elles donnent l'illusion
* d'un objet agrandi." However, there is useful seasonal information:
* "Je ne les ai observées sur le Léman que par des temps calmes, et
* lorsque la température de l'air est notablement plus chaude que celle
* du lac; mars, avril et mai sont les mois où elles sont les plus belles."
* Reprinted, with a faked "mirage photograph," in "La Nature" 25:1 (1897).
* Cited by C.Abbe in the next item.
* Good review article with some references
* Leans heavily on the papers of Charles Dufour and F.-A.Forel;
* follows the latter's classification, and discusses the Fata Morgana.
* He thinks everything is explained in Mascart's Traité d'Optique .
* [Cleveland Abbe edited MWR from 1872 to 1909; later his son, C.A.Jr.
* took over.]
* A novice discovers mirages
* This seems to be the first of Constantin Maltézos's "tunnels" papers
* A disappearing city; Lord Rayleigh invoked in favor of "total reflection"
* quoted from the "Echo" on 9 Sept.
* "I believe that Lord Rayleigh some time since suggested total reflection
* as affording at least a partial solution of some of these phenomena, in
* preference, or, in addition, to the refraction and simple reflection of
* the older theory."
* No. 1747, Sept.16,1898
* ROBERT W. WOOD's excellent EARLY MIRAGE PHOTOGRAPH in San Francisco
* This seems to be the FIRST PUBLISHED MIRAGE PHOTOGRAPH, preceding Alfred
* Wegener's 1907 photograph, published in 1911, by about a decade.
* "The refracting layer is probably only a thin skin of warm air, which
* adheres as it were to the surface of the flagstones, for the mirage is
* unaffected by the strong winds which frequently sweep the top of the
* hill." [cf. McNair, 1920.]
* Oct.20, 1898 issue
* E.M. 68 series started by Query 94348
* No. 1752, Oct.21, 1898
* Reply to Query 94348 -- EARLIEST MIRAGE PHOTOGRAPH CLAIMED
* ". . . I possess a photograph of a church spire in Tenby, halfway up which
* appears an inverted image of what was afterwards identified as the gunboat
* Gadfly , then being launched at Pembroke Dock, 12 miles distant. Though
* it was taken so long ago as May 5, 1879, it is possible that copies can
* still be procured if the photographer, Robert Symons, St. Julian-street,
* Tenby -- is still in business. The editor of the Photographic News , and
* chief of the photographic department at Woolwich, said: -- `Mr. Symons
* must be congratulated: he is the first to photograph that most romantic
* phenomenon, the mirage.'"
* According to Eric Hutton, "Glatton" was the pen-name of Mr. Clement
* Stretton [ref. No. 3105 p327]
* No. 1758, Dec. 2, 1898
* RESTRICTED HEIGHT of visibility; nice BEACH MIRAGE
* (Report of a talk by Major MacMahon to the Camera Club)
* "One very curious thing about mirage is that it depends very much upon
* the position of the eye: a few inches in the height of the eye may make
* all the difference. On one occasion on the plains of India he observed a
* mirage which was only evident when he was at a particular height; there
* was only a vertical space of two or three inches in which the effect could
* be seen, so that these phenomena may easily escape notice. A singular
* effect may sometimes be observed at a particular spot on the south coast,
* and very likely at other places, when the waves come in on to a very hot
* beach; if you place the eye about a foot from the ground and look parallel
* to the wave fronts you can see an image of the wave two or three feet
* above the real wave."
* No. 1767, Feb. 3, 1899
* STREET and LATERAL (MURAL) MIRAGES
* Report of R. W. Wood's mirage photography on San Francisco streets
* (not cited, but obviously refers to the 1898 paper in Nature).
* Also, a reference to mural mirages with both direct and reversed images,
* which certainly predates Hillers's report!
* Nr. 495, 5.April
* R.W.WOOD's mirage demo essentially repeats Gruber's experiment
* Note that he admits Wiener's writeup (1893) is better
* Cites Everett's 1874 paper.
* [I forgot to copy Plate III but it is only moderately interesting.]
* DARK STREAK
* Eastern shore seen from Chicago, Dec. 20, 1900: "The view was elevated
* above the horizon and was enveloped in a pale blue light. It formed
* the lower lining of a maze of darkness that hung over the lake shortly
* after noon and was visible for more than an hour.
* "There was a dark streak between it and the horizon."
* BORCHGREVINK's Antarctic mirages and Novaya Zemlya observation
* "On May 15th we had the last greeting from the departing sun.
* The refraction of it appeared as a large red elliptical glowing
* body to the north-west, changing gradually into a cornered square. . . .
* The promising effect of that evening . . . lasted until the returning sun
* again made the peaks and crevasses shine on the 27th July.
* "Both during the time the sun was low in its descent and when
* it rose again, a strong mirage effect was observed towards the west,
* showing images of icebergs far below our horizon, and Antarctic scenery
* only visible to us through this phenomenon. This strong mirage remained
* after the sun's return late in the summer, and the opening of the ice was
* prophesied to us in the mirage long before the ice-fields near Victoria
* Land broke.
* "It was very interesting to see the picture of far-away broken
* ice-fields, with their dark channels and towering icebergs, in the
* north-western sky; and on several occasions towards the time when the
* vessel was expected back, members of my staff returned to the camp in
* enthusiasm, thinking to have discovered the masts of the Southern Cross
* in the mirage, so strongly did their hopes confirm the impression made
* by the wonderful creations in the air."
* (Nice to see the WISHFUL THINKING factor made explicit.)
* Mentioned but not cited by Frazer (1929).
* This is the reprint edition; the original was published by George
* Newnes, Ltd., London, 1901.
* SUSPENSION of islands; "TUNNELS"
* "FOG": "Parfois, l'île paraît suspendue tout entière, une bande
* laiteuse, brillant, s'interposant entre elle et la surface de l'eau."
* The "tunnels" are the reflected images of dips in the miraged terrain.
* Some data are given on the HEIGHT effect (changes in 40 cm, 2 m).
* He seems a novice at the mirage game, but the observations are good
* and the SKETCHES are accurate.
* Here he quotes Aristotle and Theophrastus.
* cited in Maltézos's 1912 paper
* A useful review of the FATA MORGANA in the Strait of Messina!
* Boccara claims to have read everything published on the subject!
* There is a half-page footnote quoting Minasi's etymology of the term
* "Fata Morgana"; it seems far-fetched.
* Unfortunately, so does his explanation of the phenomenon; the paper is
* most valuable for his own observations, and the references.
* He confines his attention to the Strait of Messina (whose local
* geography, he thinks, is responsible); so Forel, etc. are ignored.
* He dismisses Kircher's explanation, saying: "And with him are put
* together Giardina, [and a host of others], all of whom, not having seen
* the phenomenon, as they say explicitly or make clear by their arguments,
* can only be repetitive, both in the invented descriptions and in the
* puerile explanations." (p. 201)
* But there are some serious errors: he believes the F.M. is not a
* mirage, because "the images are erect". He accepts the idea of multiple
* images displaced sideways (i.e., "lateral mirages").
* A copy of Willem Fortuyn's engraving for Minasi is Fig. 1 (p. 203)
* There is an extensive annotated bibliography at the end.
* For a summary in English, see Nature 67, 393-394 (Feb.26, 1903).
*
* Available from Google Books (with OCR text, but a badly aliased version
* of Fortuyn's engraving), and from ADS (no text, but much better figure):
* http://adsabs.harvard.edu/abs/1902MmSSI..31..199B
* See Talman (1912) for a good summary in English.
* QUANTITATIVE MEASUREMENTS of inferior mirages, showing vertical stretching
* N.B.: Pernter was the publisher of Met.Z.!
* J Fenyi, S.J. (note accent over e: "Fényi")
* Despite the title, this is not an optical illusion, but a fine
* LATERAL MIRAGE at the surface of a hot smokestack.
* The author's attempt to explain differences between naked-eye and
* telescopic views led to his optical-illusion notion.
* [Cf. Nölke (1917) for the image-location problem.]
* A Fata Morgana review in Nature, prompted by Boccara's 1902 paper
* in Mem. Soc. Spett. 31, 10. Reproduces Boccara's drawings (see P&E).
* Is "G.H.B." the "G.H.Baines" who wrote a GF note in 1910?
* Probably not. A more likely choice is George Hartley Bryan, FRS,
* who wrote many items for Nature around this time. Whoever he was,
* "G.H.B." reviewed some more Italian works on mirages in 1908.
* Number 1739
* Early modern observation of road mirage
* FINE REVIEW article on FATA MORGANA in Strait of Messina
* This is a French translation of Boccara's original in Mem.Soc.Spett.
* There is a half-page footnote quoting Minasi's etymology of the term
* "Fata Morgana"; it seems far-fetched.
* Boccara claims to have read everything published on the subject!
* Plate VI, mentioned in the second part, appears in the first one.
* However, some errors have crept into the translation, such as the
* statement in §7 that Capozzo made no additions to Saffiotti's letter.
* Both parts are available at ADS.
* Another great REVIEW ARTICLE on Fata Morganas: GIOVANNI COSTANZO
* Cites everybody (Agrippa, Facellus, Carnevale, Politi, Reina, Kircher,
* Gaspari Schott, Minasi, Pindemonte, Houel, Ribaud, Saffiotti, Boccara).
* He skipped Giovene, and has de Ferrariis only in an addendum. There
* are extensive quotations from unpublished letters, and from newspapers.
* Costanzo cites the Amsterdam reprint of Kircher's Ars Magna , quoting
* Angelucci's letter -- but with the "Salome" typo corrected -- and
* mentions the Roman editions of 1645 and 1647.
* A table (p. 123) compares the various observations.
* The dateline at the end says "Napoli, marzo, 1903".
* Costanzo's revised version
* Here a few more observations are added to both the text and the table.
* The addendum "SULLE MUTATE DI TERRA D'OTRANTO" has been removed.
* The dateline at the end says "Napoli, Maggio, 1903".
* Maltézos discovers the oil slick???
* This starts out with a mirage report, and then refutes Lazzaro's
* criticisms that the mirages reported earlier were only optical illusions.
* Then he goes off on a tangent:
* "Tandis que la surface de la mer présentait une agitation due à une
* multitude d'ondulations différents, coexistant, la surface des plaques ne
* présentait qu'une seule espèce d'ondulations, de plus grande longeur
* d'onde."
* ". . . le phénomène est dû, pour les uns à des souillures de l'eau par
* diverses matières étrangères . . . ."
* "BLACK LINE" (der schwarze Strich) discussed (cf. his distorted-sunrise
* paper in Met.Z. earlier in 1904; this issue is No.10, but dated Feb.15)
* Wilhelm Krebs argues that the horizontal black line seen in the mountain
* sky is due to reflections at an inversion layer, not an aerosol
* boundary. (cf. his distorted-sunrise paper in Met.Z. earlier in 1904;
* this issue is No.10, but dated Feb.15)
* He also argues that multiple features in the rising Sun could be due to
* WAVES on an inversion, thus prefiguring Fraser's 1975 suggestion;
* (cf. Garnier, 1899, for a less definite, but similar, suggestion).
* Citing von Wrangell's observation: "Bei Beginn der Morgendämmerung sah
* er am östlichen Horizont den schwarzen Strich in der scheinbaren Form
* einer grauen Wolkenbank von etwa 1° Höhe." (cf. FOG file)
* Detailed study of mirages and refraction in tunnel
* The importance of FIELD-GLASSES in a first-hand report
* In response to a boy's letter reporting "a ship upside down in the sky",
* the writer (editor?) says:
* "Not long after I received this letter I was riding in a fast
* express-train across the sandy plains of New Mexico, where the only
* vegetation was a few low scattered shrubs and some tufts of coarse
* grass. On the nearer parts of the lake there were beautiful islands
* with trees and shrubs . . . and I remarked to a fellow-passenger: `. . .
* Perhaps there may be interesting water-birds that have nests among those
* tall grasses and shrubs. It seems to be a better home for the pelicans
* than on those muddy banks by that small river a few miles back.'
* "He smiled. He had been over the road half a dozen times, he told
* me, while this was my first trip.
* "`Try your field-glass,' he merely remarked.
* "I did; and, like a beautiful dream that is lost on waking, the lake
* disappeared when viewed only through the glass. Later, as the train
* came nearer, I saw that it was only sand and scattered shrubs and
* grass."
* Edward F. Bigelow's "Nature and Science for Young Folks" column runs
* from p. 1032 to 1039; only the "mirage" section is cited here.
* Two separate reports from different ships
* The first reports "SURF" all around the horizon, after a
* water-temperature drop of 3 C with constant air temp., near 41 N, 54 W.
* The captain changed course from WNW to SW.
* "Ich glaube, daß dieses Phänomen eine Fata Morgana
* (Seeluftspiegelung) gewesen ist. Wahrscheinlich haben wir die Küste
* von Neufundland etwas nördlich von Kap Race gesehen."
* The second reports "land" ahead and on both sides: "Deutlich vermochte
* man Höhenzüge, sogar einzelne Bäume zu unterscheiden, und so
* überzeugend was die Erscheinung, daß Kapitän Bodmann das Schiff über
* den anderen Bug auf östlichen Kurs legte, um vorläufig, der Sicherheit
* halber, von diesem verwirrenden Phänomen wegzuliegen. Da nun aber nach
* der ziemlich gut festgestellten Position des Schiffes wirkliches Land gar
* nicht in Sicht kommen konnte und die Erscheinung nach und nach auch am
* östlichen Horizont auftrat, überzeugte sich der Kapitän von der Bramrah
* aus, daß es sich nur um eine Luftspiegelung handelte. Daraufhin wurde
* der westliche Kurs wieder aufgenommen." (near 56 S, 66 W)
* "v.S." is probably von Schrötter. (Feb. issue)
* "G.H.B." on Italian mirages again
* This time he reviews Garbasso's papers, and Rolla's lab simulation
* of Parnell's observations.
* Number 1998
* Claimed mirage of a rainbow, but impossible at 45° altitude
* (Some halo arc is a more likely explanation.)
* C. Fitzhugh Talman's Fata Morgana article, summarizing Boccara and
* Costanzo, and citing Forel and Ramage as well. A good summary of the
* observations, with a decent copy of Fortuyn's engraving for Minasi.
* (Thanks to Eric Frappa for a good PDF copy!)
* Typical mirages on St. Lawrence River, seen from Alexandria Bay, N.Y.
* ". . . seen during the spring and autumn months . . . when cloudy skies
* prevail, and soon after northerly winds have set in and the weather
* is growing colder . . . several small islands, about 2 miles away, . . .
* appear as though they were situated on a snow-covered ice field with the
* trees standing out in strong relief, giving the appearance of a dead
* calm . . . . in reality the wind is strong and the water quite rough,
* for north winds blow against the river current.
* "The most interesting feature is that if one ascends a nearby bluff
* about 25 feet high, the illusion disappears entirely, and the islands,
* surrounded by the rough, blue waters, and the trees take on their
* natural look."
* (Cf. Büsch, 1800; Abbot, 1854; and Forel, 1895.)
* Nov. issue
* Maltézos summarizes his mirage studies, and quotes Aristotle again
* The quotations from Aristotle turn out to be:
* "Problems" XXVI. 53: "Why, when the east wind blows, do all the things
* seem larger?" and
* "Meteorologica" III. IV (p.253 of the Loeb Library edition):
* "Distant and dense air does of course normally act as a mirror . . . ,
* which is why when there is an east wind promontories on the sea appear to
* be elevated above it and everything appears abnormally large;. . . "
* and unfortunately Aristotle then drags in the Moon illusion.
* VILHJÁLMUR STEFÁNSSON's astute remarks on "suggestion" in the Arctic
* After a brief description of the deceptive-appearing mirages, he says:
* "I think it is David Hanbury who tells of mistaking a lemming for a
* musk-ox, and Lieutenant Gotfred Hansen speaks of being astounded by
* the courage with which his dogs attacked a polar bear, and of being
* dumbfounded not only at seeing them killing the bear but more especially
* at one of the dogs bringing the bear back in his mouth. It turned out,
* of course, that the polar bear had been an Arctic fox. In things of
* this sort there is always a certain amount of suggestion; Hanbury had his
* mind centered on musk-oxen, and Hansen was expecting to see a polar bear."
* He then tells of seeing a grizzly bear that turned out to be a marmot.
* "The main reason for such cases of self-deception is that one sees
* things under circumstances that give one no idea of the distance, and
* consequently one has no scale for comparison. The marmot at twenty
* yards occupies as large a visual angle as a grizzly bear at several
* hundred, and if you suppose the marmot to be several hundred yards away
* you naturally take him for a bear. There is, under certain conditions
* of hazy Arctic light, nothing to give you a measure of the distance,
* nothing to furnish a scale to determine size by comparison."
* (available on Google Books)
* WILHELM HILLERS -- MURAL MIRAGE PHOTOGRAPHED
* Eilhard Wiedemann's additional Arab mirage refs. to supplement Erdmann
* Unfortunately, he uses "Fata Morgana" for inferior mirages here.
* Eilhard was a son of Gustav Heinrich Wiedemann, who assumed the
* editorship of Ann. Phys. after Poggendorff's death.
* Hillers applies his model to Vince's observations
* He shows that an inflection point in the temperature profile is required
* Hillers generalizes his model, removing a restriction to small T changes
* Note that he comes up with the "magic number" of 1° 20'
* Hillers compares theory with observation in nature as well as in his
* laboratory simulation.
* He discovers the interference fringes later seen by Raman (1959).
* [see also J.Macé de Lépinay and A.Perot (1889).]
* This is a fine piece of work!
* This is Hillers's complete, detailed work
* "Wie es scheint, liegt aber noch nirgends ein Vergleich der Theorie
* mit der Erfahrung vor; noch niemals ist es bisher geglückt, die zur
* dreifachen Bildentwickelung notwendige anormale Dichteänderung der
* Atmosphäre gleichzeitig mit der Beobachtung der Luftspiegelung
* durchzumessen." (p. 3)
* "Ferner muß nach theoretischen Erwägungen die Winkelgröße des
* Gesamtbildes stets recht klein bleiben, es wird bei normaler Entwicklung
* niemals über 20 Bogenminuten hinausgehen können. Eine gewöhnliche
* photographische Aufnahme wird deshalb von dem Schauspiel auch kaum
* etwas zeigen. Handzeichnungen, denen man öfter begegnet, sind stets
* nach Fernrohrbeobachtungen ausgeführt und lassen leicht die Größe
* und die »Bildmäßigkeit« überschätzen." (pp. 3 - 4)
* On carrying out the desired comparison, he finds that "der ganze
* Vorgang der Abbildung sich in überraschend dünnen Schichten abspielt."
* He discusses the ASTIGMATISM of the image, pp. 42-44.
* THREE SUNS, one above the other, about 2 degrees apart (cf. Hevelius!)
* This short paragraph precedes his GF report.
* O'C #223
* Pedagogical treatment of street mirage
* Mirages appear DARK:
* ". . . dann findet man bald eine Stelle, die ganz dunkel erscheint."
* ". . . erscheint es einem ganz sonderbar, daß man diese Strasse
* jahrelang zu jeder Tageszeit begangen hat, ohne diese Luftspiegelung zu
* bemerken."
* Hubbard was a participant in the Mesopotamian campaign
* There are two parts here: the eyewitness account on p. 60:
* "Our caravan . . . straggled over two or three miles of country,
* and to anyone riding somewhere near the middle the head and tail of
* the procession seemed always to be marching through a smooth, shallow
* lake; occasionally, for some unfathomable cause, the mules and men would
* execute a bewildering feat of `levitation' and continue their progress
* in the sky. Often we saw a lake spread out on the horizon, stretching
* a long arm towards us to within a few hundred yards; at other times
* a clump of palms or a group of mounted men appeared in the distance,
* only to resolve themselves, as we approached nearer, into bushes of low
* desert scrub or a grazing flock of goats."
* Here there is a footnote on the "curious incident . . . reported to have
* happened . . . at the beginning of the Mesopotamian campaign:
* "Our men, after a particularly courageous attack across the open
* desert (which at the time was such a sea of mud that they had to advance
* at the walk), reached the Turkish trenches and put the Turks to flight.
* The enemy were now in the same predicament as the British had been in
* just before, and provided a splendid target for our artillery as they
* floundered through the mire. A gunboat was lying in the river, and the
* men in the tops were watching the proceedings when they were surprised to
* see our guns suddenly stop firing, although the Turks were still easily
* within range. It transpired later that, to the eyes of the gunners on
* the desert level, the target had disappeared into the mirage ."
* Quoted by Hurd (in the 1937 Pilot Chart article)
* "houses and trees with writing underneath" at sunset
* "People living in the Karroo are accustomed to see mirages in the veldt,
* but not at sunset nor during wet weather, as far as my own experience
* goes."
* might be a cloud miraged?
* This seems to be the original account of the battle stopped by mirage
* "Fighting had temporarily to be suspended owing to the mirage, but
* upon this lifting our offensive continued." [on April 11, 1917.]
* Presumably this is the dispatch from Lt.-Gen. Sir Stanley Maude.
* quotes but does not cite the previous item, mis-dating it the 10th
* (April issue; See p. 294 for the quote.)
* Story of Turkish retreat caused by mirage "in the early days of the
* Mesopotamian campaign."
* Seems to be taken from Mrs. Eleanor Franklin Egan's stories in the
* Saturday Evening Post .
* (Oct. issue; see pp. 295-296.)
* ROAD MIRAGE between Canton and Alliance, Ohio: SMOOTH SURFACE required
* Two letters from a resident of New Castle, Pa., with the Editor's
* explanation between them. The first reports: "On July 24th, while
* traveling in an easterly direction between Canton and Alliance, Ohio, I
* noticed a car about half a mile ahead apparently perfectly reflected in
* the roadbed, as if the latter was flooded with water. . . . the road in
* front was straight almost to the horizon and an exceptionally fine
* cemented brick surface. When I came up to the `given point' I found the
* road perfectly dry and the car ahead again showing a reflection in a
* perfectly mirror-like surface about the level of the bottom of the spare
* tire. I called the attention of the rest of the party to the
* reflection, they seeing it very plainly, then and several times later
* when similar stretches of roadway offered, but each time only above the
* heated brick surface.
* "I have traveled the roads in this section since the high wheel days
* of 1885 but have never been favored with any such phenomena."
* The second letter says, "Since receiving your reply . . . , I have been
* out mirage hunting with some friends and have been successful in bagging
* some beauties as well as establishing a list of requirements . . . .
* "The requirements are a very hot, dry, clear day, and a smooth hard
* road (brick gave the best reflections) . . . ." He adds sketches that
* illustrate the need for the observer's eyes to be "just above the level
* of the level piece ahead." This usually requires the observer to be in a
* slight dip. "The best point of observation I have found is the stretch
* between Canton and Alliance, but any similar road should give equally
* clear reflections."
* [NOTE: When I was a small boy, I remember this part of the Lincoln
* Highway was still paved with bricks.]
* This was when Sci.Am. was "bedsheet" size -- hard to copy!
* Looming and mirage at sea
* "with air at 63° F and sea surface at 53° F, "Strong mirages
* noted all around. Four other ships . . . appeared at times to be steaming
* along at the top of a hugh [sic] wall of ice; at other times the bodies
* of the ships seemed to rise out of the water at least twice their height.
* Horizon had all the appearance of a long, rugged coast line.''
* July issue
* Inferior mirage seen over a road "just after dusk"
* Oct. 3 issue
* A mural mirage reported in Garden St., Cambridge!
* Cf. his 1892 note in Am. Met. J.
* cites Knowlton (above)
* ought to mention R.W.Wood, but doesn't
* Two responses to McNair:
* Platt mistakenly thinks it is a grazing-incidence reflection . . .
* . . . but Burr suggests these mirages "may serve in part to account for
* ideas of temporary disappearance, or dematerialization, of solid
* objects, and for occasional accounts of apparent hallucination."
* A report of large lateral displacement that needs detailed
* investigation: 6 degrees -- probably a misidentification.
* Mercanton's mirage DRAWINGS and HEIGHT EFFECTS in Greenland, in 1912:
* [actually FILED with green flashes]
* The mirage observations are on pp. 196-197.
* 1. On 15 April 1912 in the Davis Strait, "un beau mirage d'«eau chaude»"
* 2. On 27 May, a superior mirage of icebergs; "vent faible"
* 3. On 2 June "nombreux isbergs visibles au loin apparaissaient tous
* étirés verticalement et surmontés de leur image renversée et
* ratatinée. Une fine ligne sombre courait parallèlement à l'horizon
* marin, représentant, sans doute possible, [!] l'image réfléchie de
* la nappe liquide." (So, he's not always reliable.) He took a telephoto
* picture, but it wasn't good enough to reproduce.
* 4. On 10 Sept., "j'ai vue sur quelque trente kilomètres de côte
* se développer une fatamorgana très belle. Elle se présentait sous
* l'aspect d'un ruban horizontal, strié de lignes verticales floues
* correspondant aux linéaments du paysage recouvert par le dit ruban.
* Celui-ci était nettement limité en haut et en bas. Son bord inférieur
* se découpait sur la mer, sa lisière supérieure sur le paysage côtier.
* Devant de Hjortetakken il marquait le 1/6 de la hauteur apparente de
* cette montagne, soit les 200 m inférieurs. . . . Quelques isbergs . . .
* apparaissaient très nets et dans leur position normale mais étirés
* et coiffés dès le tiers supérieur de leur image renversée, limitée
* par ailleurs strictement au bord supérieur de la zône floue.
* "La largeur verticale de la dite zône variait d'ailleurs en sens
* inverse de la hauteur de l'œil au-dessus des flots."
* The title pages are given in both German and French; I give only the
* German here, as de Quervain (despite his name) writes only in German
* and was the expedition's leader; and this was published in Zürich.
* Dated 1. Dezember 1920; abstracted by Brooks in MWR, 1923.
* Account of a meeting of the Roy. Met. Soc.
* "A paper on the Mirage, by Dr. W.H.Steavenson . . . . The visibility
* of the mirage was found to be dependent solely on the distribution of
* temperature near the ground . . . not necessarily associated with hot
* weather, and had, in fact, been well seen when the shade temperature
* was below 50° Fahrenheit. Investigations had shown that the old
* reflection theory was untenable, and that the phenomenon was purely a
* refraction effect. . . . The paper was illustrated by actual photographs
* of the mirage, taken by Dr. Steavenson with a telephoto lens." (p.421)
* [The published paper is the next item (1921).]
* Dated Dec. 1920. Available from ADS.
* HEIGHT EFFECTS + PHOTOS
* Use of mirage for DESERT NAVIGATION (cf. Hassanein Bey, 1925)
* Rosita Forbes (1893-1967) nearly died in the North African desert.
* "On clear mornings, about an hour after dawn, when the desert is
* very flat, a mirage of the country about a day's journey distant
* appears on the horizon. For a few minutes one sees a picture of
* what is some 50 kilometres farther on. The Arabs call it `the
* country turning upside down.'" (p.135)
* Another note by Du Shane, commenting on McNair (1920)
* He mentions but does not cite his earlier observation.
* Fine example of LOOMING
* accompanied by detailed temperature and wind data
* "sea 1 . . . air 43 F, sea 39 F"
* "The ice presented a curious mirage effect, being reflected upwards.
* When first sighted with the sun on it, it looked very like a continuous
* line of chalk cliffs in a slight haze; with the sun behind it, small
* detached pieces appeared as dark blurred objects which might be anything,
* and might be mistaken for land. On closing, it was found to be floating
* not more than a foot or so above water."
* LOOMING and STOOPING of other ships reported as well.
* Fine example of LOOMING and "FOG"
* originally cited as "Bay of Plenty Times" of Dec.6, 1920
* "All this time there was a dark grey-blue band on the horizon . . . .
* Soon after 4:30 this bank appeared to condense from the surface of the
* sea towards its upper margin, till it resembled a thick dark-coloured
* cable stretched from island to island."
* Note the Editor's WRONG explanation of the "black band", which confuses
* radiance and irradiance !!
* More comments on the previous letters to Science
* Arctic "CLIFFS" mirage that sets like a heavenly body
* Vilhjalmur Stefansson is following Storkerson's trail:
* "Beyond Cape Grassy we found that Storkerson had struck away from the
* land in a direction 22 degrees west of north which is the proper course
* for Cape Murray . . . . But four miles from Cape Grassy we found a place
* where the sledges had stopped briefly by the way, to judge by the tracks
* of men and dogs. After this the trail led for eleven miles in a
* direction 20 degrees east of north. . . . But after eleven miles of this
* course the party had turned back to their previous one, heading again
* for Cape Murray. I learned later that the reason had been one of the
* remarkable mirages or `appearances of land' that have deceived so many
* arctic explorers. Storkerson told me later that the fog had suddenly
* lifted, showing a land with bold cliffs apparently only fifteen or
* twenty miles away. This surprised him, but after consulting his
* companions, both Eskimo and white, and studying the land carefully
* through the glasses he made up his mind that they could probably reach
* it that day and that he might as well strike it first at this cape and
* follow it westward. But for two or three hours as they advanced the
* land kept receding and getting lower, until finally without becoming
* obscured by any fog or mist it sank beneath the horizon as if it had
* been some heavenly body setting."
* Met.Mag.'s brief account of the next item
* TRIPLE SUPERIOR MIRAGE
* Several mirages and other phenomena (Kenneth Sinclair, Maughold Head
* Lighthouse, I.O.M.) "ORKNEY WITCH" original report
* ". . . I remember the remark of a Highland fisherman made to his fellow
* boatman after directing his attention by a sweep of his massive hand to
* the northern sky. . . . `there's Margaret, the Orkney witch, going to meet
* the sun.' and there, sure, hung, as if suspended by invisible threads, a
* stretch of the Orkneys mapped in the sky. I remember the sea was smooth
* and the sun glaring."
* PERIODIC MIRAGE and the ORKNEY WITCH
* ". . . in the Pentland Firth the superior mirage is sometimes referred to
* by the name of `Margaret, the Orkney Witch'. . . ."
* ". . . as sure as the timely rise and fall of a fountain ball, so did this
* strange sight rise and fall as if governed by the movement of some sighing
* bosom."
* "Such direct evidence for Helmholtz waves in the transition layer
* between a warm current and the cold air beneath it is valuable."
* NOT a FATA MORGANA (according to Bonnelance, 1929) but an inferior mirage
* decent photograph reproduced
* pretty standard mirage story (stapled with the previous paper)
* "absolutely characteristic" FATA MORGANA (according to Bonnelance, 1929)
* NOT a FATA MORGANA (according to Bonnelance, 1929) but an inferior mirage
* This is a repeat of one published in Mon.Wea.Rev. for June 1923 (above)
* Report in the Times by "P. Neame, Lieutenant-Colonel, Royal Engineers"
* [quoted in full in the QJRMS report, so not copied.]
* "Mr. F. S. Smythe and I were climbing the Finsteraarhorn in the Bernese
* Oberland on May 2. . . . Suddenly at 11.55 a.m. the image of a ship
* appeared in the sky just to the east of the Eiger peak, floating in
* a blue shimmer just beyond the visible horizon. This lasted for a
* minute or so, and then vanished. Very soon after a line of five ships
* appeared farther east, funnels and masts clearly distinguishable. This
* image lasted for some fifteen minutes, and varied in its clearness from
* time to time. The ships appeared of course greatly exaggerated in size,
* and were right way up, not inverted."
* "On reference to an atlas, this brings their position on the nearest sea to
* approximately the eastern exit of the English Channel into the North Sea, a
* distance of some 400 miles."
* ILLUSION of ships in SUPERIOR MIRAGE
* This is hard to classify: first, Neame's report in the Times is quoted;
* then comments on it by Newnham and Whipple. I'll isolate Neame's item
* as a separate entry (above), and attribute just the comments here.
* However, note that in April, 1924, MWR indexed this under "Neame".
* Newnham just gives the synoptic situation. But Whipple says:
* "The illusion of distant ships would seem to be explicable by the
* presence of an inversion of temperature. . . . The illusion of the ship's
* masts is comparable with that of reeds growing by the edge of water in the
* 'inferior' mirage of the desert. A similar drawing out of a small object
* can often be observed through a windowpane of poor glass." (p. 281)
* Saved as "AlpineMirage1923.pdf"
* EXTREME LOOMING
* Hard to believe they saw mountains 750 km away,
* ". . . jedoch ließen sich die mächtigen Schneegipfel und ihre von
* Klüften zerfurchten Abhänge überaus deutlich wahrnehmen."
* The feet of the mountains couldn't be made out, so maybe the long
* path is explicable by the great height (4560 m) of the peaks.
* A garbled footnote refers to Jessen's (1914) mistaken observation.
* Cf. Garner (1933).
* Use of mirage for DESERT NAVIGATION (cf. Rosita Forbes, 1921)
* On p. 124, after mentioning the ordinary (inferior) mirage, he says:
* "Another kind of mirage comes sometimes in the early morning. Then the
* country far ahead of one appears in the sky at the horizon, as the
* Bedouins say, `upside down.' This is not, as the other variety of
* mirage is, entirely an illusion. It is really the reversed reflection
* of the country thirty or forty kilometers ahead of where the observer
* stands." He also says, "Sometimes . . . a small pebble the size of a
* cricket-ball seen from a mile away might assume the appearance of a big
* rock, standing like a landmark. The skeleton or part of the skeleton of
* a camel or a human being may take on the most fantastic shapes on the
* horizon, but the Bedouins know it well."
* and: "The seasoned desert traveler knows a mirage when he sees one. It
* is entirely possible indeed that the `upside down' variety may be a
* positive assistance, since it can suggest what kind of country lies ahead."
* FATA MORGANA with LATERAL MIRAGE (according to Bonnelance, 1929)
* textbook example of MULTIPLE HORIZON due to INVERSION
* Seen at Hampton Beach, Mass., June 17, 1925.
* Sounds like Forel's "FATA MORGANA" displays. 8' HEIGHT.
* "The Isle of Shoals looked like a city of skyscrapers of uniform
* height. . . . The loomed horizon joined with the other farther and farther
* northward in the course of the hour from 10 to 11 a.m. The extending
* upper line of the loomed horizon became visible first in rather regularly
* spaced spots (marking air waves?) which developed columnar connections
* with the lower sea level as the top line became continuous. A rough
* angular measurement indicated the looming to be about eight minutes
* of arc.
* "Over the ocean there was the normal cool cushion of air, represented
* by the moderate sea breeze at 59° F. blowing in from the ocean (shore
* water 54.5° F.), over which was beginning to run a warm southwesterly
* wind, which became strong by mid-afternoon at points a few miles inland."
* [The islands are about 20 km from the beach.]
* A mirage photograph discussed, not very informatively
* WEGENER's statistical support for superior mirage predicting warmer
* weather
* MIRAGE CLASSIFICATION (preliminary version; see his 1929 paper in BSAF)
* This is on the first leaf of No.2; the title says "Tome IX" but that
* must be an error, as the title page of the *volume* says Tome VIII (1926)
* Mirages across Lake Ontario; random reports in discussion
* Available from ADS.
* Ivanov reports miraged sunsets from Anapa (Northern Caucasian coast of
* the Black Sea) and cites Wright's experiments with colored filters.
* He shows crude MIRAGE DRAWINGS of setting Sun (all Omega type)
* Maltézos reports his work as well, in response to Bonnelance's note
* The page numbers overlap with the previous item, as Ivanov's drawing
* is placed on p.219, in the middle of Maltézos's letter.
* PHOTOGRAPHS of SUPERIOR MIRAGES in the Alps, by A. Vaupel
* Commentary by Alfred Wegener (June issue)
* Nice observation of HEIGHT effect, and "SURF"
* "From a rowboat, the low, rocky coast of one of the outlying islands was
* seen to alternate rapidly between its normal shape and that of splendid
* `cliffs.' The alternations synchronized with the rising and falling,
* respectively, of the boat over the slight swells of a glassy sea. So thin
* was the refracting layer of air, that when the boat was on top of a swell,
* the distant coast appeared in its true character to a person sitting in
* the boat. When the boat was in the trough, up popped the `cliffs' to form
* a fine palisade along the whole visible length of the island. From the
* deeper troughs the looming very nearly went over into full mirage, the
* normal form of the island shore then shooting out horizontally bottom up,
* over the true shore. . . . The most spectacular feature of the display was
* the magnificent `surf' made by the very moderate swell when its breaking
* coincided with the dips of the boat into troughs. The spray would at such
* times shoot upward in a brilliant white column as high as the `cliffs'
* produced by the momentary looming."
* Aug.-Sept. issue
* Lengthy but fanciful descriptions of mirages in the manner of James Gordon
* Mentions "FOG" on p.7. Also:
* "A mirage is the reflection of something; sometimes the mixed
* reflection of several things. It appears that an object or a landscape
* is lifted, perhaps by reflection, projected afar, and then set down in
* another place as a mirage. . . . It may be photographically clear, or
* vague and cloudy, or a confused mixture. This confusion may be due to
* several reflections mingling in the same picture . . . ." (pp. 7, 8)
* "The mirage shows many ambiguous images. Desire often insists we are
* seeing the thing we want." (p. 9)
* "The turning of my field glass upon a mirage often changed it into
* nothing -- or formless light and shadow." (p. 12)
* There is a nice description of how a mirage made a couple of stalks
* of grass appear to be distant spruce trees in snow (pp. 16-17): "Before
* me, two slender grass stalks stood above the snow. I circled back to
* where I had first seen the spruces. They were in view again, but this
* time they were upon a snowy rim of a cañon -- the magnified
* overlapping snowshoe tracks that I had made by the grass stalks."
* There is a good description of a "breathing" or waving mirage on
* p. 18: "Up and down they rose and sank, teetering as though upon an
* invisible support laid across the peninsula. Sometimes they balanced or
* swung back and forth slightly as they seesawed."
* Peary's "Crocker Land" is on pp. 21-22.
* "During the Franco-Prussian War a number of scattered and independent
* observers in northern Sweden and Norway saw mirage armies marching
* through the air, equipped like the real ones that were fighting a few
* hundred miles to the south." (p. 23) [but no references!]
* "A vague or confused mirage . . . often reveals something in the mind of
* the onlooker." (p. 25)
* "Generally, the image shown is not moved to one side, but just
* uplifted above the horizon's rim. That these mirages often are directly
* above the real, I have proved with islands in the Pacific by taking a
* compass course and sailing directly to the real island." (p. 27)
* Bonnelance's detailed statistical study of the frequency of different
* forms of refraction during the year and their relations to temperature
* gradients. He finds a rough relation to temperature difference between
* air and water, but not to humidity or barometric pressure. Comments on
* the importance of a trained eye.
* Dubious lateral mirage of mountains
* The explanation proposed by R.Corless does not seem plausible.
* Wimperis calls attention to his 1903 note in Nature:
* "The shapes of these ships are distorted when the temperature of the sea
* is higher than the temperature of the air . . . wind force makes no
* difference . . . ."
* Comments from an unobservant reader:
* "I have not observed any road mirage in my time and am an octogenarian . . . ."
* Report of persistant inferior mirage on a tarred road at airport
* ". . . it was visible both in winter and summer (although less intense in
* the former season) under most conditions of wind, weather and temperature.
* . . . Even with a damp road and drizzle falling one was considerably
* surprised to find that, on approaching what appeared from a distance to
* be a puddle of water, the puddle vanished." (Cf. Ashmore, 1955)
* Describes LABORATORY DEMONSTRATION of mirages (syrup + water; hot-plate)
* Curious terminology: "hot" and "cold" mirages, as the surface layer is
* (compared to those higher up). He also makes a hot-wire refraction,
* with no mirage counterpart: a shadow zone around the wire, with
* "brightly coloured interference bands."
* July 21 issue.
* STANDARD TRIPLE IMAGE with drawing of SUPERIOR MIRAGE
* "The day was hot and clear with a temperature of about 65°."
* Available from ADS.
* Mirages studied on sandy beaches
* Notable for observations in the LAMINAR layer.
* DOUBLE SUN, compared by F.J.W.Whipple in the following comment (p.68)
* to Hevelius's observation in 1682. He points out that it does not
* appear to be 2 images of the Sun separated by a blank strip; I am not so
* sure. This is the observation invoked by Botley (1935).
* "In the path of the pillar there was an image alike in all respects to
* the sun, the distance between the two balls being equal to the diameter of
* either. It was quite impossible at that time to say which was the object
* and which the image but this was decided when, two minutes later, the
* upper `sun' quite suddenly faded."
* cf. Emsmann, 1856, as well as S&T, 1980.
* Calvin Frazer's mirage article
* Despite the title, this is about mirages, not variable dip. Contains
* several interesting references (but not citations) to Bonnefont (1837);
* Warren Upham (1895); Lt. Wilkes; Borchgrevink; Bottineau. Alas, the
* "accompanying illustration" by Arctowski was not published.
* SUPERB treatment of mirages observationally; much improved classification
* scheme compared to his 1926 paper. Schiele's review missed this.
* Many comments on FOREL's work; good FATA MORGANA discussion:
* "La Fata-Morgana . . . atteint et déforme des objets plus ou moins hauts
* et donne continuellement l’impression que l’on regarde le paysage à
* travers la longueur d’uneplaque de verre qui en donnerait une image
* confuse, étirée ou multiple." (p. 497)
* Useful comments about "FOG", which he seems to equate to the Fata-Brumosa.
* Useful comments on earlier reports in BSAF, too; see notes elsewhere here.
* EXCELLENT ADVICE to observers (cf. Nijland's list for GFs)
* He also notes the unexplained nature of "lateral mirage" reports.
* Interesting review of mirages at sea, with many examples
* badly drawn OMEGA sketch
* Claims that mirages in Kansas are less frequent than before farming of
* the plains, due to the effects of more plant cover. Several anecdotal
* accounts of mirages there.
* (cf. Fingado, 1932)
* impossible balloon sounding explained by abnormal refraction at inversion
* LOOMING and cases of LONG VISUAL RANGE due to refraction
* Cites examples of long triangulation baselines: 192 miles [309 km]
* from Mt. Shasta to Mt. St. Helena, and 183 miles [295 km] in Utah.
* Then, on p. 73, there are examples of seeing great distances: the
* Explorer , in 1911, is said to have seen the Fairweather Mountains
* at 330 miles [531 km]. Other examples of looming on land are given.
* Cf. Korzenewsky (1923).
* CHARLES FITZHUGH TALMAN's article in Yachting
* An EXCELLENT popular review! Mentions Justice's note in MWR, 1930; the
* mirages of Mt. Canigou seen from Marseille; mirages near Chicago on Lake
* Michigan; Thomas Jefferson's "canoe" mirage; and many classical examples.
* Very clear on terminology -- a specialty of his, according to the obit.
* Explicitly says: "When abnormal refraction increases the apparent
* elevation of distant objects -- often lifting above the horizon things
* normally below it -- the process is described as `looming.' Because we
* associate a certain apparent altitude with a certain distance, this
* phenomenon generally makes the objects seem nearer than they really are."
* Excellent advice: "The yachtsman who wishes to become better
* acquainted with mirage . . . if he knows enough German, . . . will read the
* appropriate sections of Pernter and Exner's Meteorologische Optik , and
* his best guide in English will be W. J. Humphreys' Physics of the Air .
* . . . A good pair of binoculars or other optical aid will be found necessary
* for making out details, especially in the observation of superior mirage,
* as great distances are usually involved . . . ."
* Much of the wording is borrowed from his earlier works.
* This mag has had a varied history. Founded in 1907 by Yachting
* Publishing Inc., it made its way to Z-D, then to CBS Magazines, who sold
* to Diamandis Communications, bought by Hachette Magazines c. 1987; then
* they sold it to Times Mirror Magazines, Inc.. In 2000, they sold it to
* Time, Inc. In 2008 it was acquired by Bonnier Magazine Group. It is
* still publishing 2 volumes/year in an unbroken series.
* I have a *very* poor photocopy -- can anyone provide a good one?
* Mirage of Isle of Man from Holyhead, with looming
* SKETCHES of mirages, reproduced in Minnaert's book
* The drawings are about as reduced as is tolerable, here; but they were
* reduced still further, to illegibility, in Minnaert's book.
* [For larger versions, see ten Kate (1951).]
* Fig. 6 is a nice superior mirage of a ship beyond the horizon, like
* the drawing with the Sun in M.O. 37, 18 (1967).
* I don't think Pinkhof's argument against the supposed mirage of the
* cliffs of Dover holds water; he forgets that towering can magnify the
* image -- cf. Met. Mag. 56, 40 (1921), where again "chalk cliffs" were
* imagined. But he may well be right that this interpretation was wrong.
* Nice REVIEW of mirages and looming in mistaken claims of polar discoveries
* See some other of his papers in the "Lehn/Novaya Zemlya" file, esp. the
* 1937 paper for an update of this topic.
* GOOD PHOTOGRAPHS of mirages
* Good PHOTOGRAPHS of mirages (Tafel 46)
* Okt. 1934
* DOUBLE HORIZON; DEVELOPMENT of the superior mirage above 3 boats in 5
* minutes, from masts downward.
* GOOD REVIEW of mirage phenomena, with discussion of terminology, and a
* mention of Diodorus Siculus at the end (probably via Flammarion).
* Thesis -- good references
* This is a good guide to the mirage literature. There is a good
* review of the classical treatments -- particularly, a fine appreciation
* of Biot's monograph, Wegener's theory, etc.
* The second part develops the ellipsoidal case in series, using
* perturbation theory. Today, it would be easier to just do the
* numerical integrations, as van der Werf has done.
* Cited by Humphreys (1940) in connection with the mention of Japanese
* Fata Morganas on p. 107; however, the ellipsoidal theory is never really
* applied to that situation.
* Rudolf Meyer FIRST DISCOVERED the Mock Mirage ("intermediate mirage")
* too many good quotes to give here!
* Rudolf Hans Wilhelm Meyer (1880-195x?) was educated in Warsaw and
* Berlin, after being a student at Dorpat Meteorol. Obs. He was born in a
* suburb of Riga, and often contributed to the Korrespondenz-Blatt there.
* O'C #88
* Good DRAWINGS showing a DOUBLED image with one part TILTED
* July issue
* Good DRAWINGS and FOG description
* "The appearance of a fog bank lay on the horizon, the angular height of
* which was 2° 10'." This complex display needs work.
* Jan. issue
* Not a Fata Morgana, but a spectacular case of LOOMING,
* in which a farm appears (and a town is reported to have appeared)
* at "less than 10% of the real distance." Not even a drawing.
* Observed on 20 May.
* Humphreys was probably the inspiration for Fraser's "Theological Optics"
* This note also mentions the incident of April 11, 1917 reported by
* General Maude. [see London Times for April 16.]
* GOOD CASE for a MOCK MIRAGE in MOUNTAINS
* From Donnersberg (835m) mirages described in abstract as "Fata Morgana"
* were seen of Fichtelberg (1214m) and Keilberg (1244m), 71 km away.
* "Fichtelberg und Keilberg sowie sämtliche Bergkuppen bis herüber zum
* Wieselstein (Entfernung = 26 km NW, h = 856 m NN) standen auf sich selbst
* Kopf, nach oben begrenzt durch eine messerscharfe, waagrechte Linie."
* "Sämtliche Berge verloren ihre ursprüngliche Form. Vor allem der
* Oedschloß-Berg im Duppauer Gebirge (Entfernung = 70 km SWzW, h = 925 m
* NN) machte alle Stadien von Klumpen, feinst zugespitztem Kegel bis zu
* einem sonderbar geformten Zylinderhut durch. Auch das Riesengebirge
* (Entfernung 130 km E, h = 1400 bis 1600 m NN) zeigte, wenn auch nicht in
* so deutlich wahrnehmbarer Form, die im Westen so ungewöhnlich stark
* auftretenden Luftspiegelungen."
* Mountains were about 15 C warmer than valleys; "Der Temperatur- und vor
* allem der Feuchtigkeitssprung (Donnersberg nur 3% rel. Feuchte!) lag bei
* rund 750 m NN."
* GOOD REVIEW OF DESERT MIRAGES (ALL KINDS)
* Ives had degrees in geography and geology, but had a minor interest
* in meteorology, which led to a few publications on mirages.
* This paper is particularly interesting in describing some rare mirage
* phenomena, esp. on pp. 468-469. The inversion of 15°F in one inch of
* height reported on p. 468 exceeds the 1°C in 5 cm inversion of Balsley
* et al. (2003) by an order of magnitude.
* Superior mirages are discussed on pp. 469-471, including association
* with inferior mirages. Miraged nocturnal lights are treated on p. 470.
* Fata Morgana mirages are on pp. 471-472. They "not infrequently have
* peripheral color fringes" -- cf. Minasi! -- and are complicated "in many
* instances" by "wisps of steam fog".
* More remarks on mirages by Ives, with climatology
* The brief mirage discussion is just pp. 175-176. After mentioning
* the common inferior mirages (and accompanying turbulence), he says:
* "Less common in this area are superior and multiple mirages, occurring
* when the lower layers of air are thermally stratified. These are
* particularly common over the Gulf of California, and on the west side of
* Baja California, where the California Current (Fig. 17) chills the lowest
* stratum of air, producing great stability, and leading to stratification.
* "Near the sea, particularly in areas where high mountains are quite
* close to shore, Fata Morgana mirages are not unknown, and lead to annoying
* or serious misobservations by navigators and pilots."
* [no hard copy filed.]
* GOOD DRAWINGS showing the change in mirage with DISTANCE of ship
* Ronald L. Ives describes mirages in the Gulf of California
* while working as an engineer at Cornell Aeronautical Laboratory.
* This is a VERY THOROUGH OBSERVATIONAL REVIEW of many kinds of mirage,
* with clear drawings of 3-image and other superior mirages, looming,
* and descriptions of CONCAVE appearance of the sea, truncated images and
* false horizons, etc.; "False sea horizons, due to refraction, are a
* standard midday condition . . . . Fata Morgana is a common occurrence
* when cold air drainages from high mountains reach the warm waters of
* the Gulf of California." (from Abstract!)
* The section on "False Sea Horizons" is on p. 287:
* "On hot clear days, which are frequent near the Gulf of California, the
* sea horizon acquires a peculiar appearance in midmorning, the visible
* horizon being 10' to 15' of arc higher than its sunrise position.
* This condition persists until very late afternoon, at which time the
* "upper horizon" dissolves, not always regularly. Onset of this false sea
* horizon is contemporaneous with the development of a thin warm surface
* stratum of water. Neither the warm surface stratum nor the false sea
* horizon develops when the wind speed is much more than 5 mph.
* ". . . inferior mirages commonly develop over flat land areas 15
* minutes to two hours before formation of the false sea horizon. On very
* hot summer afternoons, the inferior mirages over land may merge with
* the false horizons over water.
* "Although deceptive to the unaided eye, so that its presence
* complicates accurate marine navigation, the false sea horizon can be
* distinguished from the true horizon by use of a deep red viewing filter,
* such as a Wratten "A" or "F."
* "When winds of small areal extent blow over the sea surface, they
* remove the false sea horizon locally and temporarily, in much the same
* manner that dust devils "eat holes" in inferior mirages on land.
* "In a great majority of observed instances, objects at sea
* considerably nearer the observer than the apparent horizon have an
* entirely normal appearance during the middle hours of the day, whether
* or not a false horizon is present. As these objects recede from the
* observer, they will cross the horizon and disappear below it in a normal
* manner if no false horizon is present; but will sail off into the sky,
* undergo great vertical distortion, or partake of more complicated visual
* transfigurations when a false sea horizon is present."
* On the next page: "The shallow northern part of the Gulf of
* California, roughly from Latitude 27° north to the mouth of the Colorado
* River, is noted for its mirages, which, in one form or another, are of
* almost daily occurrence at all seasons." Fig. 2 (p. 288) shows the
* progressive changes in appearance of a ship steaming away from the
* observer as it crosses the horizon. "If . . . mirage conditions exist,
* as is usually evidenced by a false horizon at sea, and by inferior mirages
* over adjacent lands, the appearance of the vessel will not remain normal
* after it reaches the apparent horizon." (p. 289)
* "Never reported from Puerto Peñasco, but common in the narrow
* channels between islands farther south, is the Fata Morgana , a weird
* mélange of diffuse and ever-changing images, perhaps magnified and
* distorted views of objects on the shore. These annoyances to mariners . . .
* are most commonly seen in the early morning, when the air is very cold
* relative to the water, and are usually accompanied by steam fogs."
* "Where study of air conditions has been possible during Fata Morgana
* displays, a thin layer of relatively cold air, in turbulent motion, has
* been present over the surface of relatively warm water. Above the
* thin cold air stratum, which usually results from local air drainage,
* is a layer of much warmer air. Other stratifications aloft are sometimes
* present.
* "Observed colors in the main body of the mirage are always
* degradations of those present in the local environment. Occasionally
* spectral hues are present, as "rainbow glints," adjacent to steam fogs
* associated with the Fata Morgana ." (p. 290) [Cf. Minasi!]
* Next comes a discussion of "looming" of distant mountains:
* "On any ordinary clear day, when air temperatures are substantially
* normal for the season, and wind speed is below about 15 miles per hour,
* dim shapes, that might be distant mountains shrouded in desert haze,
* appear on the western horizon at about noon . . . [A]bout an hour before
* sunset, . . . the images sharpen . . . . A few minutes before sunset, the
* images tower and sharpen still more, . . . This image lasts for about
* half an hour, until very shortly after sunset, at which time it darkens,
* and rapidly falls below the horizon.
* "After an abnormally hot still day, the image towers to a much
* greater height, and the sea appears to have a concave surface from the
* observer to the base of the range, with "embayments" of mirage extending
* up valleys in the distant mountains." (p. 291)
* On p. 292 he describes loomed images of distant islands to the south,
* as seen from a height of 250 ft. (76 m). They appear in midmorning or
* later, "snapping into view" about a minute of arc above the horizon.
* [This means the images appear at the inferior-mirage fold line.] "The
* images slowly rise as the day progresses," -- or, more likely, the dip
* of the apparent sea horizon increases as the mirage grows stronger.
* "Appearance of the upper images changes with each minor change in
* the position of the observer, and the actual changes in appearance
* with changes in the height of the observer's eye above sea level are
* disproportionate to the change of elevation." So, here again,
* we have an inferior mirage at the surface, with inversion (superior)
* mirages above. The similarity to Forel's account is striking.
* Thanks to Eric Frappa for an excellent PDF of this!
* Big reproductions of Pinkhof's (1933) drawings
* GOOD DEFINITION: "What is a mirage? One should be able to define this
* as the phenomenon whereby we see objects at a sufficient distance in the
* open air not singly, but double or sometimes multiple, from which it is
* obvious that the light rays that leave an object come to our eyes along
* different paths. Then the light rays are not all propagated
* rectilinearly but sometimes also along curved paths . . . . The question
* is now more how it is possible that the rays become bent."
* He is one of very few writers who contrasts the astronomical and
* terrestrial refractions; but he supposes that straight rays are possible,
* or even common; and that superior mirages are rarely seen because the
* thermal gradients there tend to be weaker, not because of the restricted
* height from which they are perceptible. However, he does emphasize the
* importance of eye height.
* FATA MORGANA discussed
* Cites his mirage article in the previous volume: "The Fata Morgana are
* also mirages, but of a much more complex form than we have described in
* the cited article."
* He correctly connects the phenomenon with air-water temperature
* differences, and especially those near land; but thinks the F.M. is due to
* CURVATURE of the isopycnic surfaces.
* a nice SKETCH of MURAL MIRAGE
* on the last page of the previous item.
* MOUNTAIN MIRAGES and nocturnal inversion data
* Comments on inadequate resolution of soundings (200 - 300 m)
* Werner Weigel, Met. Station auf dem Fichtelberg i. Erzgebirge
* Gerhard Kohl tries to explain Weigel's observation
* Notable as the FIRST paper to consider the MOCK-MIRAGE geometry
* explicitly: "Einmal handelt es sich um eine Luftspiegelung eines weit
* entfernten Objektes (rund 165 km), zum anderen lag der Beobachtungspunkt
* einwandfrei oberhalb, aber nicht unterhalb der Grenzfläche zwischen
* Bodenkaltluft und der darüberliegenden, bedeutend wärmeren Luftmasse."
* -- though he tries to force Wegener's model onto it, and
* mistakenly asserts that "die Lichtstrahlen [werden] von der totalen
* Reflexion betroffen." But at least the radiosonde profile shows an
* 8-degree inversion close to the peak-to-peak line of sight.
* Many other circumstantial details are given, as well as a tell-tale
* drawing of the mirage (Abb. 4) supplied by Weigel.
* a series of M.O. mirage reports -- NOT ALL indexed here!
* HOT, DRY GUSTS -- cf. M.O.24,13(1954).
* "In one of these gusts (at 0820) the dry bulb rose to 89 F and the wet
* bulb fell to 71 . . . ." "Sea temperature remained 76 throughout . . . ."
* Fine DRAWINGS of 3-image mirages
* NOVAYA ZEMLYA (leaky-duct) display of great duration
* Surface-based DUCT phenomena (cf. ATY's April 23, 1995 ducted sunset)
* "The upper limb of the sun appeared elongated and remained above the
* horizon for approximately two minutes." [This is the flattened image
* above the duct.] "Three minutes later a bright red light appeared,
* intermittently, in the sea about two-thirds of the distance to the
* horizon. The light was rectangular in shape, 40' of arc in length and 3'
* wide, and lasted for eight minutes." [This is the Sun seen through the
* duct. Note the long visibility -- a fine Novaya Zemlya display!]
* Evidently the observer mistook the top of the duct for the horizon
* (cf. Le Gentil's "whale" remark). The Editors were completely baffled
* by this report: "It is not possible to give any simple explanation of it. . . "
* MULTIPLE IMAGES OF VENUS and "VERTICAL WHITE STREAK" --> GF
* "Before finally setting the planet appeared elongated to a vertical
* white streak which immediately turned a bright green. All these changes
* were visible to the naked eye."
* [cf. Biot's "petite colonne de feu", and M.O.24,13(1954)]
* DRAWINGS of distorted sunrise
* (belongs in "DISTORTED" file but on same page as above)
* Seems to be a CREPUSCULAR RAY from VENUS
* ". . . gusts of hot, dry breezes were encountered, readings of the dry and
* wet bulbs then noted were 88 and 64 F . . . " [cf. M.O.23,77(1953).]
* "During the phenomena Venus was observed setting. Just before setting
* a column as of fire shot up from it to a height of a few degrees and
* remained visible for 30 sec while the planet set."
* [cf. Biot's "petite colonne de feü!]
* MOUNTAIN MIRAGES - identified as superior mirages
* Strong inversions (15 C in 540m)
* Werner Weigel, Brocken
* ASHMORE's road-mirage observations: almost unaffected by clouds
* Ashmore's by-line reads "Hon. Meteorologist to Wrexham Borough".
* Observations made by an observer sitting on the "kerb" at Wrexham,
* and using binoculars. No info on the road surface!
* Visibility in RAIN:
* "It became evident that the mirage can be formed during favourable
* conditions at any time the sun's altitude exceeds 24½° and that it is
* almost always present, whatever the conditions, with a solar altitude
* of 29° or more. . . . cloudiness may have a slight effect, but in
* general, the only conditions which prevent it are snow lying, rain heavy
* enough to produce considerable splash, or visibility less than about
* 150 yards . . . ." (p. 338) [cf. Woltman 1796, 1798, 1800, and Bigg, 1928.]
* By measuring the ray curvature (using Vedy's method), ". . . it
* appears that the temperature gradient lies mainly in a layer of air
* about ¾ in. thick, and since even the strongest winds do not upset the
* gradient, it is probable that most of it is confined to a portion much
* shallower even than that." (p. 341)
* At the end, he comments: "This work was not always easy ; the road is
* often busy, chiefly with pedestrian traffic. Naturally the activities of
* the observers, involving prone lying in the roadway, aroused curiosity;
* occasionally expressions of commiseration were overheard as passers-by
* receded from the scene."
* Cites Vedy's 1928 paper, and Miss Botley's in Weather (1952).
* (kept only as a PDF)
* SUPERIOR MIRAGE of cumulus cloudtop from airplane
* "Such phenomena as described in this paper do not appear to have been
* previously reported from aircraft in flight, unless some of the reports
* of 'flying saucers' may have been due to this effect."
* MOUNTAIN MIRAGE - identified as superior mirage; but the stretched zone
* looks like Wegener's Nachspiegelung (viewed from above).
* The mirror image is drawn equal in size to the erect one.
* Milleschauer (835m) seen from Fichtelberg (1214m) above "Nebelmeer" at 750m.
* A 1958 Dutch newspaper clipping found by R. H. van Gent in a copy of
* Flammarion's "l'Atmosphère":
* Besides giving the wrong date ("1708" !) for Monge's observations, and
* exaggerating the French army's reactions to the desert mirages ("the
* men thought the end of the world had come"), there are a couple of
* tantalizing hints of mirages seen from AIRPLANES:
* "The pilot Martin flew into a mountain peak 30 years ago [this is dated
* 1958] when he tried to evade a mirage. Lindbergh himself said that he
* had seen strange shores in the middle of the Atlantic Ocean."
* James H. Gordon's mirage summary
* Useful remarks on the difference between ASPHALT and DIRT surfaces,
* despite his ignorance of the literature and optics. Cf. his 1923 paper.
* Good line: "Mirages are definitely not photogenic."
* Penny Porter tells me James Gordon was Janet Gordon's father.
* Trautmann's attempt to interpret mirages of the Alps
* This is a useful but problematic report. The mirages are merely
* described (no drawings). But the observations are accompanied by
* balloon soundings from Munich, roughly on a line between the observers
* on Gr. Falkenstein and the miraged mountains. Unfortunately, only
* Wegener's simplified theory is used, so the comparison of theory with
* experiment is not exact (although he does demonstrate that ducting
* conditions existed in 2 of 3 superior mirages). Worse, he supposes that
* "reflections" can occur at the inversion layers seen below eye level;
* so the attempts to interpret these supposedly "inferior" mirages are
* nonsense. The resulting disagreements are "explained" by some
* hand-waving arguments of little merit.
* Obviously, this needs to be re-done properly.
* [Cited by Löw in his "Luftspiegelungen" book.]
* DISTORTED MOONRISE with INFERIOR MIRAGE (textbook example)
* good drawings
* DISTORTED MOONRISE with multiple MOCK MIRAGES (Filed in GF file!)
* good drawings
* BOTLEY mixes up mirages and other phenomena
* James H. Gordon's short note
* "These road mirages are a comparatively modern development, almost
* unknown on the old dirt roads, and rarely seen today over dirt surfaces."
* Ford Times was a travel mag put out by Ford Motor Co.
* Thanks to Penny Porter for providing a copy!
* REGULAR MIRAGES IN BAJA
* Visual and radar looming compared; "FOG" observed
* During the "fog" episode, the air was 2.5 deg. warmer than the water;
* apparently the inversion then lifted and became inaccessible.
* "A star fix taken by two officers from seven stars came out with useless
* results, although stars and horizon appeared good visually. While
* searching for the error that might have caused the useless results, it
* was found that if 10 min were added to the height of each observation,
* the results would have been correct." [Cf. Koss's footnote, 1901]
* [Note observation of CONCAVE surface:]
* A lighthouse with normal range 15 miles was seen at 75 miles.
* This appears to be a clear case of NEGATIVE DIP (cf. Hasse's
* "Kimmfläche") caused by a strong inversion overhead. The editor's
* comments are mostly wrong and should be disregarded.
* N.B.: There is no apostrophe in the title of this publication.
* TRIPLE-IMAGE mirage within "yellow band . . . thought to be dust or haze.
* The yellow colour was very distinct and it may have been significant
* that the sun was setting over mountains around the coast at the time."
* A miraged ship was seen at 12 n. mile radar range; "the effects
* persisted until each observed target came within seven nautical miles . . .
* On two occasions the inverted image was observed before the true
* object." Air temp. 17.1 C, water 15.2, wind force 2.
* Fraser's parabolic profile
* He mentions the more correct logarithmic profile, but does not use it.
* Interesting DRAWINGS of superior mirages, with ships towering
* Radar distances of targets given.
* Inferior (?) mirage effects on HORIZON, 4 April 1979
* A vessel "was observed fine on the port bow. At a range of 8 n. mile it
* was seen to be in a normal position on the visible horizon, but when at a
* range of 12 n. mile it appeared in very clear detail to be in a position
* above the visible horizon.
* "At the same time a small fishing vessel, at a range of 9 n. mile and
* approximately 4 points on the port bow, was producing a wake on the
* horizon which appeared to the observer as a mountainous sea, see . . .
* sketch. This phenomenon persisted until the range had decreased to 7 n.
* mile." Air 5.5° C, sea 6.3; wind calm.
* LOOMING of trees on shore, despite inf.-mir. temps.
* ". . . there appeared to be a layer of shimmering haze above the land
* . . . the trees were estimated to be 7 n. mile distant from the vessel."
* The DRAWING shows 2 separate layers at least.
* "HAZE" is drawn dark, despite Sun's altitude of 30-40°.
* Air 11.7° C, sea 14.1. A complex and puzzling observation!
* Interesting DRAWINGS of superior mirages, with SMOKE MIRAGED
* The measured altitude of the boundary at 51' is unusually large.
* WAVY HORIZON DRAWING
* An otherwise undistinguished inferior-mirage observation, which calls
* attention to the irregular waves on the apparent horizon. At 11.5 n.
* mile range, a vessel appeared miraged (usual drawing). "As the vessel
* drew closer the fo'c'sle, masts and accommodation appeared to hover above
* the horizon, seemingly separated from the rest of the vessel, which could
* not be observed at the time. Although the sea was calm with only small
* ripples, the waves at the horizon appeared magnified." Air 10.8 C, sea
* 13.2; wind, light airs. Position 39 20 N, 73 18 W (i.e., probably in
* Gulf Stream).
* DRAWING of multiple beach images
* "Initially an apparent line of haze or mist was observed, extending from
* the horizon to an altitude of 0° 10' - 0° 13' and presenting a false
* horizon. The ship's funnel smoke was then observed trapped on a level
* with this, indicating an inversion . . . . As the vessel closed with the
* coast the land was noticed to be apparently sitting on top of the
* inversion level, with the line of beach repeated two or three times in the
* shimmering air below (Figure 2). Sometimes water could be seen between
* the layers of the beach . . . . The top layer did not remain solid-looking.
* At intervals sections would dissolve into narrow vertical blocks that
* resembled single trees before disappearing altogether (see Figure 3); this
* resembled a wave-like motion, with the top layer gradually dissolving from
* right to left, then re-forming from left to right with waves of varying
* thickness forming in the top layer, and ripples moving along the top."
* Air temp 21.0° C; sea 19.5; wind force 2.
* DRAWINGS of superior mirages and miraged ship
* "Shortly after departure from Cape Town a superior mirage was observed
* to extend around two-thirds of the visible horizon. Throughout the
* following 2 1/2 hours very vivid inverted images could be seen. It
* was noted at 1300 GMT and again at 1630 that there were quite marked
* discontinuities of the reflected horizon. The two most distant images
* were observed at 1300 and 1400 GMT, the first being Dassen Island, which
* at the time of observation lay 13 n. mile to the north (the visible
* horizon being 7.85 n. mile distant); the height of Dassen Island is 19
* metres." Air temp. 22.9° C, sea 18.1, wind force 3 increasing to 4.
* Many interesting DRAWINGS of superior mirages, with radar ranges
* "As the Strait of Belle Isle was approached a thick, low band of
* refraction was observed to stretch across the entrance to the Strait."
* Air, 5.9; sea, 4.1 C.
* Drawings of looming of a ship.
* Enlargement of image claimed with no distortion.
* Nice photos. This guy had a whole series of interesting papers for
* several years in Z.Met., all nicely illustrated, on halos, subsuns, the
* shapes of icicles, etc.
* This paper has beautiful illustrations of inferior mirages over lakes.
* The author doesn't understand Fraser & Mach's paper in Scientific
* American, though; he insists on "reflection" without refraction.
* NICE SUPERIOR MIRAGE PHOTO (triple image)
* This really belongs in BLM file, but is in my mirage file because of photo
* ". . . conditions such as these are common in southern California, as
* evidenced by the well-known distortions of the solar limb as the sun sets."
* [Cf. O'Connell's book.]
* Interesting DRAWINGS of towering and superior mirages of icebergs
* at 38 - 43 nautical mile range
* ". . . all the bergs observed at a distance of 18 n. mile and over were
* seen to be abnormally refracted."
* Strong SUPERIOR MIRAGE produces "A SOLID WALL OF WATER" (see DRAWING)
* ". . . what appeared to be land features were observed on the horizon; at
* the same time the horizon ahead of the vessel became distorted and gave
* the impression that the vessel was approaching a solid wall of water. . . .
* The nearest land at this time was 85 n. mile away."
* Air varied from 25.6 to 21.6 C, sea temp. 18.8 C; wind force 2, sea
* slight. "Exceptional radar detection" to 45 n. miles.
* Many SUPERIOR and TRIPLE-IMAGE MIRAGE DRAWINGS in "mist"
* radar ranges from 8.0 to 17.5 n.miles; dry bulb 22.0 C, sea 15.8,
* wind force 1
* Mirage of coasts described, but the sketch "cannot be reproduced"!
* Many interesting details; a puzzling report.
* GOOD DRAWINGS of superior mirages with vertically stretched zone
* Air temp. 30 C, water 26; wind force 3.
* Strong inferior-mirage near Grand Bahama Island, with DRAWING
* Ship at 16 n. miles ahead seen miraged. "Slowly, this effect diminished
* until . . . at a range of 12 n. mile, the ship's hull touched the horizon."
* Air 21.2 C, sea 27.0; wind force 3. "The sea state was slight, with no
* swell." The background land was also miraged.
* SUPERIOR MIRAGE PHOTOS
* Adelbert von Chamisso's 1816 mirages in translation
* A very clear explanation of both the appearances and their causes:
* "I saw a surface of water before me in which a low hill was reflected
* that extended along the opposite shore. I went toward this water. It
* disappeared before me, and I reached the hill with dry feet. When I had
* covered about half the distance, I seemed to Eschscholtz, who had remained
* behind, to have been submerged up to my neck in the reflecting layer of
* air, and, shortened the way I was, he said I looked more like a dog than a
* human being. As I strode onward, toward the hill, I emerged more and more
* from the layer of air, and I appeared to him, lengthened by my reflection,
* to get taller and taller, gigantic, slender."
* "When land rises above the horizon, as seamen are wont to express it,
* the line that is taken to be the horizon is the edge of a reflecting
* surface formed by the lower layer of air and closer to the eye; a line
* that really lies below the visible horizon. I believe that this illusion
* in some cases can have an influence on astronomical observations and can
* cause an error in these of five and perhaps more minutes."
* He also mentions Flinders, Ross, and Scoresby.
*
* NOTE: Johann Friedrich Eschscholtz was the physician and naturalist who
* accompanied Kotzebue's expedition, along with writer/botanist Chamisso
* and the artist L. A. Choris. Chamisso produced the first scientific
* description of California's golden poppy (now the state flower) on this
* expedition, and named it in honor of his friend Eschscholtz.
* The best biography of Chamisso I have seen is in the DSB.
* Good DRAWINGS of towering of ship; another "yellow band" within 1 hr.
* of sunset; cf. Marine Observer 49, 23 (1979).
* ". . . a low, yellow-coloured sand layer was observed, originally thought
* to be haze or fog." Air temp. 25.5 C; sea decreased from 20 to 15,
* then increased to 18 C.
* drawing of triple-image mirage
* with standard commentary by Ken Bignell
* Adrienne Mayor's fair popular review: Tape, Greenler & Fraser are cited
* Besides the standard examples, several less-common ones are mentioned:
* accounts from Giraldus Cambrensis's Topography of Ireland (1187),
* literary passages supposedly inspired by mirages (Wordsworth;
* Coleridge); Wilkes and J.C.Ross; Borchgrevink.
* Jan.-Feb. issue
* SUPERIOR MIRAGE DRAWINGS and descriptions, including land seen
* inverted beyond horizon (25 n. mile range). The mirage of land at 18
* miles was slightly magnified. Wind: force 4.
* INVERSION of SCORESBY's drawings
* See Lehn & Rees (1990) for correction.
* REALLY GOOD piece on inferior mirages by CRAIG BOHREN!
* (with 3 fine color photographs of hot-road mirages.)
* First sub-head is: A Mirage Is Not an Illusion (Thanks, Craig!)
* "I shudder when I see or hear mirages referred to as optical illusions.
* . . . these optical phenomena are no more illusions than are images
* in a mirror." (He offers the Moon Illusion as a real example: "An
* enlarged moon is a creation of the mind; a mirage is a creation of the
* atmosphere.")
* "When images formed by the refracting atmosphere depart markedly from
* what they would be in its absence, they are called mirages."
* "Before considering the consequences of atmospheric refractive
* gradients, I must dispose of the notion that water vapor plays an
* essential role in the formation of mirages. This misconception dates to
* antiquity and persists today, evidence that no misconception ever dies."
* But, alas, he equates inferior mirages with images below the geometric
* position. Despite this single flaw, a fine article.
* Nice Wollaston-style demo using HEAT LAMPS and water
* "When the lamps are switched on, the beam immediately begins to deflect
* . . . . After 30 s a deflection of 6 cm is observed on the screen. . . .
* The deflection rapidly returns to zero when the lamps are switched off."
* Unfortunately they define inferior and superior mirages in terms of
* image displacement, blaming this on Greenler's 1986 OSA abstract. But
* at least they say mirages "are caused by gradients in the temperature"
* and not temperature differences -- still, no second derivatives.
* Rees never read Biot's book, though it is his first reference!
* ". . . inverted mirages . . . are not included in Biot's analysis . . . ."
* Lehn corrects the old Rees (1988) inversion
* This deals with the UNIQUENESS problem, in part.
* Rees et al. introduce the Runga-Kutta forward model
* A worse-than-average account by ignorant physicists
* "Monge . . . was the first to give an explanation . . . . The coordinates at
* which zero slope is reached can be approximated . . . ." A crude empirical
* approximation for the temperature profile over a hot surface is used (with
* no physical basis); the index of refraction "must approach a constant" (!)
* at heights "greater than about 2 m"; and of course the Earth is flat.
* They touch on the horizontal-ray paradox. Pretty dismal.
* 5 papers, all in Am. J. Phys., are cited from 1974 to 1982.
* A glorified version of Wollaston's demo
* The use of a pinch of Coffee-Mate to make the beam visible is a nice
* contemporary touch. And as "alcohol is not benign to most transparent
* plastic containers," he recommends a strong (0.5g/ml) sugar solution.
* our MOCK MIRAGE paper (Paper I)
* Mirages, polarization, and insect vision
* Shows a photograph of a Tunisian mirage
* Thanks to Gábor Horváth for supplying a PDF copy!
* Mirages, polarization, and insect vision (erratum)
* This shows a corrected version of Fig.1
* Thanks to Gábor Horváth for supplying a PDF copy!
* All qualitative, but good photographs
* MURAL MIRAGE well photographed
* But much of the discussion is confused: the erect image is described as
* "real"; Hillers is wrongly credited as being the "first" to study "the
* wall mirage"; the ray trajectory is assumed to be parabolic, or circular;
* the refractive-index and temperature profiles are arbitrarily assumed,
* with no reference to the relevant boundary-layer literature; etc.
* Dec. issue
* Penny Porter's Fata Morgana Arizona observation, plus quotes from Gordon
* The observation was made at 7 am in April 1981
* "A city afloat on a vast blue ocean . . . . doorways on dwellings framed
* in timber and ladders stretching from the ground up to occasional arched
* windows of the upper levels -- suggesting the architecture of the
* pueblo-builders of Arizona or Mexico. Garden plots on upper terraces
* blazed with fiery flowers. Chickens scuttled around courtyards. Two
* heavily laden burros tied to hitching posts were clearly visible, and
* people strolled down quiet, peaceful streets. . . .
* "Finally it broke into sections. Huge fragments collapsed, and in
* slow motion they sank one by one into the sea."
* distant lights seen at night via inversions -- fine MIRAGE PHOTOS in color
* Notable for a good section ("Animation and human factors") that
* discusses the perceptual issues. The colors reported remind me of
* the Biot-Arago observations. Cites my mirage page.
* Formerly available on the Web at
* http://www.optometrists.asn.au/ceo/backissues/vol86/no2/2043
* Presently available on the Web at
* http://onlinelibrary.wiley.com/doi/10.1111/j.1444-0938.2003.tb03069.x/pdf
* Ed Darack's article on MARFA LIGHTS featured on cover
* Nice COLOR PHOTOS of inferior and superior mirages of lights, including
* Fata Morganas. Cites my mirage page.
* Mila Zinkova's good Fata Morgana picture of glitter (see cover!)
* Contains comments by ATY. Nice mock-mirage GF shown, too.
* No. 11 (Nov. issue)
* Siebren's 2011 paper on inferior-mirage wiggles
* He understands the cause of the alternation, but uses a bad temperature
* profile.
* Nice COLLECTION of MIRAGE PHOTOGRAPHS from Spain
* Good examples of the main types, including FM; shows effects of height.
* But: "Although there are descriptions of mirages since the Classical
* Antiquity, the first scientific explanation was given by Gaspard
* Monge, who accompanied Napoleon Bonaparte in the Egypt campaign . . . ."
* doi:10.1088/1742-6596/274/1/012001
* Nice COLLECTION of MIRAGE PHOTOGRAPHS from Spain
* Good examples of the main types, including FM; shows effects of height.
* ISBN 978-989-95095-7-3
* DAVID FARMER's excellent mirage of Mt. Rainier, with my ray-traces
* Siebren van der Werf's nice paper on "sea fences", with waves and animations
* This is a close match to the next item; read both together with the
* Lehn & Schroeder papers (1981 and 2003).
* https://doi.org/10.1364/AO.56.000G51
* my paper with Eric Frappa
* Explains the FM with valley-circulation model (thick inversion)
* many photographs, and a real-time video
* Should be read together with Siebren's paper, just above.
* [Note observation of CONCAVE surface.]
* https://doi.org/10.1364/AO.56.000G59
* Mila ZINKOVA's "Sunset mirages" paper in "Weather"
* http://dx.doi.org/10.1002/wea.3056
* VISIBILITY in RAIN; temperature and humidity data; no profiles
* "It was observed that mirage has shown up from morning to afternoon,
* from 07.00 AMuntil 18.00 PM, even until sunset. Mirage is also still
* visible when the weather is cloudy or drizzling, but disappeared when
* heavy rain." [Cf. Ashmore (1955), above]
* "When the air temperature is high and the humidity is low, the mirage
* appears with high visibility (very thick), so that it can be observed
* clearly visually. Conversely, when the temperature of air is low and
* the humidity is high, mirage appears with low visibility (very thin)
* or almost non-existent or completely gone. [Abstract]
* "Mirage is an optical illusion. . . ." [first sentence!] "The light
* undergoes refraction and total internal reflection . . . ." [first para.]
* "Mercury thermometers are installed at an altitude of 1.5 km from
* ground level." These seem to be naked-eye observations. The broken
* English does not help: ". . . no mirage can be seen on the second morning
* of the day" seems to mean the second observation of the day. They were
* surprised to see no mirage at daybreak on a hot day, and attribute this
* to the effect of humidity. Not useful.
* Nasrullah Idris, Maswati, T. N. Usmawanda,Arlin Maya Sari
*
* This also has the title:
* Voyage de Humboldt et Bonpland. Première partie. Relation Historique.
* The various editions and many translations divide the "books" into
* volumes in various different ways.
* MIRAGES and TERRESTRIAL REFRACTION are mentioned occasionally; one needs
* an edition with an index to find them.
* Note the flowery dedication: "A L'Illustre Auteur de la Mécanique
* céleste, P. S. De La Place, comme un faible hommage d'admiration et de
* reconnoissance."
* Helen Maria Williams's translation, often reprinted. Lacks an index.
* This is a rather crude, literal translation, but at least it is
* unabridged. I have found mirages mentioned in Vol. 1, p.187;
* Vol. 2, p.189 (the footnote citing Hooke); Vol. 3, pp. 542-554
* (the famous Note D); Vol. 4, p. 292; Vol. 4, pp. 299, 325, 327-329.
* The last of these is the passage referring to the Sanskrit phrase, and
* to "the Indian, Persian, and Arabic poets".
* On p. 542 is a reference to "Gruber, (Ueber Stralenbrechung und
* Abprallung des Lichts, 1793)." This may be a later offprint of his
* 1786 work?
* The translator has the quirk of invariably writing "it's" for "its".
* Humboldt's detailed mirage report (see Note D, p. 625)
* This is the original, now available from Gallica.bnf.fr
* This is the republication sponsored by the Humboldt Foundation:
* "Neudruck des 1814-1825 in Paris erschienenen vollständigen Originals,
* besorgt, eingeleitet un um ein Register vermehrt von Hanno Beck"
*
* By far the most interesting passage is Note D on pp.625-631 of Band I.
* It contains quantitative measurements of zenith distance (though
* mostly on the scale of his quadrant, which contained 96 degrees, each of
* which corresponds to 56' 15") of several fixed points on islands, and of
* the sea horizon. He thus was able to observe the VARIABLE DIP and its
* relation to air and water temperatures, and to the color of the sea (p.
* 628). He cites Aristotle, Theophrastus, Büsch, Gruber, Monge, Brandes,
* Wollaston, Tralles, Woltmann, Biot. He mentions the Sanskrit phrase
* "mriga-trichná". He cites his own demonstration that, in the tropics,
* the water is nearly always 1 to 1.5 degrees warmer than the air, as the
* cause of the miraging. Most impressive!
* The Hooke citation is on p. 296 here.
*
* Glaisher's 1865 Oct. 2 ascent, confirming NOCTURNAL INVERSIONS
* [Cf. Brandes (1806), who may have been the first to notice them.]
* ". . . an accidental descent just at the time of sunset showed very
* little or no difference of temperature for a height of nearly half a mile.
* The question then arose as to whether it was possible that at night the
* temperature might increase with elevation, and not decrease as always
* heretofore had been considered . . . ." (pp. 367-368)
* "The results of this first night experiment are very valuable; and,
* so far as one experiment can give, indicate that, on a clear night,
* the temperature, up to a certain elevation, increases with increase
* of elevation." (p. 370)
* Comment on REFRACTION:
* "Certain it is, from the very remarkable results obtained from the
* night ascents, which might, with sufficient number of observations,
* have important bearing both on the theory of astronomic refraction and
* on the theory of heat, that nocturnal observations deserve repetition
* and extension." (p. 373)
*
* These remarks are repeated, without the tabular data, in his part of
* "Travels in the Air"
* Google Books has several scans of this, but only the Harvard one
* is complete.
* Tissandier's part of this 19th-Century ``coffee-table'' book contains
* his brother's woodcut of the mirage over the English Channel, facing
* p.408, in "Troisième Partie: Voyages de MM. de Fonvielle et Tissandier":
* "Nous cherchons les falaises de Douvres et nous nous étonnone bientôt
* de ne pas voir les côtes de l'Angleterre qui ne sont pas bien distantes
* de notre aérostat; elles sont cachées par un immense rideau de vapeurs
* plombées, qui s'étend vers ce côté de l'horizon. Je lève la tête
* pour chercher la limite de cette muraille de nuages, et quelle n'est pas
* ma stupéfaction quand j'aperçois dans le ciel une nappe verdâtre qui
* ressemble à l'image de l'océan; bientôt un petit point semble se
* mouvoir dans cette plage céleste, c'est un bateau, gros comme une
* coquille de noix, et en y fixant avec soin mes regards, je ne tarde pas à
* constater qu'il navigue à l'envers sur cet océan retourné; ses mâts
* sont en bas et sa quille en haut. Un moment après je vois l'image du
* bateau à vapeur qui vient de partir de Calais pour l'Angleterre, et, avec
* ma lunette, je distingue la fumée qui s'échappe de son tuyau. Voici
* bientôt deux ou trois autres barques qui apparaissent au milieu de cette
* mer magique, tableau vraiment saisissant, d'une éblouissante
* fantasmagorie du mirage."
* The popular summary of Gaston Tissandier's 24 balloon flights
* The first chapter (pp.119-127) contains a textbook example of the
* SEA-BREEZE circulation (see diagram, p.125) with a capping inversion at
* 600 m. It alludes to the mirage over the English Channel, but says the
* first 7 flights were described more fully in Hachette's "Voyages
* aériens" (1870).
* Drawings of distorted Sun- and Moon-rises are on pp. 260 & 261.
* There is a 2-page bibliography of aeronautics at the end.
* Tissandier's review of "mirages" -- some may be snowflake reflections?
* (The Eiffel-tower reflection is from l'Astronomie 9, 41-42 (1890), q.v.)
* Here is where he quotes extensively from his earlier work, but
* mis-attributes it to "Histoire de mes ascensions". The illustration by
* his brother Albert, showing the inverted images of ships on the North Sea,
* accompanies this article. As this illustration was based on his
* "crude sketch" made after the flight, it can hardly be regarded as an
* accurate observation.
* NOTE: Gaston Tissandier was the founder, in 1873, of "La Nature".
* Eric Frappa tells me this is "Semestre 1".
*
* (mostly minor references to mirage phenomena)
* N.B.: Admiral Smyth was the father of Charles Piazzi Smyth, q.v.
*
* "The deceitful phenomenon so well known in Barbary by the name of
* `sarab ,' is very frequent in the lower grounds of Sardinia; and while
* at Villa-Cidro, I one morning saw the whole Campidano appearing like a
* vast lake, with the hills of Cagliari in the distance resembling islands."
* Discussion of mirages, pp. 288-291
* The Fata Morgana "is said to occur in sultry, calm weather, when the
* tides, or streamed-up waters, are at their highest, and when the sun
* shines from that point whence its incident rays form an angle of about
* 45° on the water. At such times, they tell us, multiplied images of
* all the objects existing on the two lines of coast -- as castles, arches,
* towers, houses, trees, animals, and mountains -- are presented in the air
* with wonderful precision and magnificence. Padre Minasi assures us that,
* in addition to obvious appearances, numberless series of pilasters,
* superb palaces with balconies, armies of men on foot and horseback, and
* many other strange figures, are seen in their natural colours and proper
* action, as in a catoptric theatre; and there exist paintings and
* engravings of the wonderful phenomenon. Still, on the whole, I cannot but
* repeat the conviction to which inquiry led me, and which I published as
* far back as 1824 ( Sicily and its Islands, page 109): -- `I much doubt,
* however, the accuracy of the descriptions I have heard and read, as I
* cannot help thinking that the imagination strongly assists these dioptric
* appearances, having never met with a Sicilian who had actually seen
* anything more than the loom or mirage, consequent on a peculiar state of
* the atmosphere; but which, I must say, I have here observed many times to
* be unusually strong.'"
* Here is his famous "What's in a word?" discussion
*
* See also Kritzinger (1914), Vogel (1940) in Green Flash file.
*
* Johann Jacob Scheuchzer is sometimes regarded as the "father of
* paleobotany" because of his early work on plant fossils.
* Sulzer edited Scheuchzer's works and translated them from the Latin
* edition published at Leyden by Peter van der Aa in 1723, adding later
* material from Scheuchzer's contributions to Breßlauer Sammlung as well
* as some of his own speculations on the origins of the Alps (he thought
* they were produced by the Earth's center of gravity having shifted!) and
* the fossils in their sedimentary rocks (which he explained by Noah's
* Flood). He attempts to combine the physical evidence with a literal
* interpretation of Scripture.
*
* There are many amusing bits in this work, from the editor's railing
* against people who only buy books for the pictures ["Viele Leute lieben
* die Kupferstiche weit mehr, als eine Beschreibung der Sachen; ja einige
* kauffen die Bücher nur deßwegen. Diesen verständigen Liebhabern zu
* gefallen, hat der dienstfertige Verleger der Holländischen Ausgabe eine
* Menge Kupfer beygelegt, welche aus Merians Topographie genommen sind.
* Stücke, davon oft in dem Texte kein einiges Wort stehet. Diese hat man
* hier weggelassen, und vielleicht in eben der Absicht, in welcher sie Hr.
* van der Aa dazu gethan hat. Wer diesen Abgang nicht vertragen kan, der
* hat die Freyheit, die Holländische Ausgabe oder Merians Werck zu
* kauffen."] to the description on p. 238 (the wrong page number happily
* supplied by "M" in Gilberts Annalen) on how to tell real dragons from mere
* snakes: "Bochart . . . unterscheidet . . . die Drachen von den Schlangen durch
* nachfolgende Kennzeichnen: 1) Die Grösse. 2) Den Bart unter dem Kinn.
* 3) Eine dreyfache Ordnung der Zähnen. 4) Eine schwarze, feuer-rothe oder
* aschenfarbe. 5) Eine sehr grosse Oeffnung des Mundes. 6) Daß sie durch
* das Anziehen der Luft nicht diese allein, sondern auch vorbey fliegende
* Vögel an sich ziehen. 7) Ein erschreckliches und auf gewisse Weise
* trauriges Zischen, daher sie im Hebraischen Tannin genennt werden."
* (Some 20 pages are devoted to these supposedly real creatures.)
*
* Of more interest here is his observation (p. 42) of a "Phænomenon an
* der Sonne": ". . . da sie einen gantz neuen Habit angezogen, (zum wenigsten
* habe ich sie in solchem noch niemal gesehen). Abends um 5. Uhr ist bey
* neblichtem Himmel dieses sonst so hellglänzende Gestirn, zum wenigsten
* einige Augenblicke, in Mitten dem Nebel, in einer angenehmen purpur-blauen
* Farbe erschienen." As this is seen through "fog", I take it to be a
* "BLUE SUN" and not a bluish sunset flash, despite the "few moments"; as
* the date was July 29, 1703, this would be several hours before sunset.
*
* The solar after-images are nicely described under the heading "Von
* ungewöhnlichen in der Schweiz A. 1719. im Heumonat aus der Luft
* gefallenen Bläßgen oder Bullis " with a footnote: "Sihe gedachte
* Breßl. Sam~lung im Julio 1719, Class.IV. Art.IV." The classical
* particulars are there: a hazy sky, in which people could look at the Sun
* without discomfort; a series of images drifting across the sky; a variety
* of colors seen; the "bubbles" vanish into insubstantiality on falling to
* the ground; etc. "Es ist dieses völlig die gleiche Luft-Geschicht von
* Bläßgens oder Bullis , die A. 1553 den 21. Brachm. zu Sculs im
* Engadin ist angemerckt, und in unsrer Meteorol. Helv. p.96 beschrieben
* worden . . . ." Pfarrer Judas Uttiger in Lichtensteig sends him a detailed
* account, of which he writes that "er seye um dieser sehr seltsamen
* Luft-Geschichte willen zum drittenmal spazieren gegangen, und habe sich
* nicht genug verwundern können, daß die bey ihme stehende ihme gleichsam
* mit dem Finger die fliegenden und fallenden Luft-Kugeln gezeiget, deren
* er doch keine mit seinen eignen Augen sehen können." But those who lived
* on higher hills above the fog had seen nothing; "daraus sich schliessen
* läßt, die unterste Gegend der Athmosphaer seye sonderheitlich mit
* dicken Dünsten angefüllet gewesen, da hingegen die obere hell geblieben.
* Diese ganze Luft-Geschicht endlich scheinet es, könne als ein optisches
* Gesichtspiel, oder als ein Betrug unserer Augen, angesehen, und mit
* demjenigen verglichen werden, da einer, der die Sonne mit starren Augen
* anschauet, hernach, ob er die Augen gleich zuschliesset, das Bild der
* annoch scheinenden Sonne siehet oder zu sehen vermeynt, und sie zwaren
* siehet durch verschiedne Farben als roth, blau und so ferner, untergehen,
* bis sie völlig verschwindet."
* This is followed by two more very similar reports, in the last of which
* Scheuchzer himself finally gets to see the "Bläßgen" and confirms his
* opinion: ". . . so wie nemlich das dem Aug eingedruckte Bild der Sonne,
* welches eine Zeitlang, wann man auch gleich die Augen von der Sonne
* abwendete, bliebe, eine mehr oder minder stärckere Bewegung in den
* Augen-Nerven verursachte."
*
* The whole book is printed in old-style Fraktur, with little e's over
* the letters for umlauts. The Courier-like Roman type used is a poor
* match to the Fraktur. A much wider, different face is used for display
* type (still a Fraktur face). It's amazing that anyone would actually
* send this treasure out to another library; perhaps the dowdy 19th-Century
* re-binding deceived them into thinking it worthless.
* A collection of 17th-Century oddities, collected by "Landmesser Weise"
* taken from the Theatro Europaeo .
* Pp. 106-107 relate a double-Moon crescent of 15 July 1633.
* The SOLAR AFTERIMAGES are on pp. 107-108 and 109-110.
* Erik Acharius's second-hand solar afterimage reports
* As Gilbert's German translation appears to be complete and satisfactory,
* see the next item for it.
* An early SOLAR AFTERIMAGE report (see next item for explanation)
* Also a good example of "mass hysteria" or mutual brainwashing by
* the inhabitants of a village: everybody came to believe "eine Menge
* Kugeln oder sphärische Körper nach einander mit Geschwindigkeit
* aufsteigen, die dem blossen Auge von der Grösse eines Hutkopfes
* erschienen, und eine dunkelbraune Farbe hatten." The mysterious
* "balls" vanished soon after falling to earth. One person saw them
* first, "und als es so lange dauerte, wurden nach und nach alle
* Dorfbewohner darauf aufmerksam, so dass es keine Täuschung seyn konnte,
* die bloss bei einem und dem andern Individuum hätte möglich seyn
* können." The Sun had been dimmed by a haze so "dass man ohne
* Unbequemlichkeit mit blossen Augen in sie hinein sehen konnte."
* The above phenomenon explained: ". . . der Grund der Erscheinung in einer
* Blendung der Augen durch die Sonne liege." The anonymous correspondent
* in Göttingen points out some earlier examples: "Dasselbe Phänomen
* erwähnen frühere Schriftsteller beinahe mit denselben Worten."
* Certainly true; but he gives the wrong page number (238 for 338) in
* Scheuchzer's Natur-Geschichte.
* Admiral K. P. Jessen's odd account: afterimage or bleached areas?
* After establishing himself as an experienced observer of phenomena at
* sea in "my numerous navigations, carried out in all nearly 40 years,"
* with a brief account of mirages and looming seen in the Baltic in June,
* 1895, he gets to his main theme: an observation made at sunrise on 25
* Feb., 1902, 12 miles off "Cape Boltin, on the eastern coast of Korea."
* "Standing on the command bridge together with the senior and junior
* navigating officers and the officer of the watch, I observed the rising
* sun: the horizon was perfectly clean, free of clouds and the rising
* sun appeared to us, as always, in the form of a continually increasing
* bright segment. Suddenly I, and behind me also the aforesaid officers,
* noticed on the perfectly clean disk of the sun a dark spot, continually
* increasing just like the rising sun above the horizon and little by
* little taking on the obvious form of a high mountain. In a few seconds
* a new spot appeared on the left beside this peak, gradually changing into
* another such summit, but lower, separated from the first by a deep pass.
* Finally, the entire disk of the sun was covered from limb to limb by
* a whole mountain massif, reaching to the very lowest limb of the sun as
* it rose. Just as the whole solar sphere separated from the water horizon,
* the whole phenomenon instantly vanished."
* The accompanying drawings, based on sketches made as soon as he
* returned to his cabin, show two steep mountains appearing to rise together
* with the Sun, so that their image remains fixed with respect to its disk.
* (Considering the latitude of over 40°, this is impossible.) The
* Sun's disk is shown round, with no distortions.
* "Obviously, those mountains which we saw so clearly on the solar
* disk had to be on a line between us and the rising sun. And, indeed,
* by constructing on a chart the aforementioned azimuth of the sun at the
* moment of its rising, it turned out that this line passed just through
* the high mountain Tonvumi-yama , located on the north-western part of the
* Japanese island of Nippon [sic -- he means Honshu], at north latitude
* 39° 5' and east longitude 140° 10', not far from the city of Akita.
* The distance from the cruiser to that mountain was 480 sea miles."
* An accurate calculation gives 897 km or 490 nautical miles.
* He later gives the height of the mountain as 7130 feet. The only
* mountain of this height near this location is Chokai-San; I cannot find
* any place in Japan with the peculiar name of "Tonvumi-yama" (which he
* repeats later); it might be a mistake for the lower peak Tokami-Yama.
* Photographs of Chokai-San show it has shallow slopes, like Mt. Fuji,
* quite unlike the "mountain" in the drawings. (As the Sun appears
* undistorted, the mountain should, too -- if it were real.)
* His sunrise azimuth of 77° 40' E from S (or 102.3° by the usual
* astronomical convention) agrees well with calculation for the stated
* date and coordinates. He gives the time of sunrise as 6h 4m but fails
* to state whether this was LCT or zone time; predicted sunrise for the
* ship's position is indeed 6:04 zone time, however. As "The state of
* the weather was most ordinary: a light breeze and calm sea" and the
* accompanying table of meteorological data shows the water and air to
* have the same temperature within a few tenths of a degree, the most
* reasonable conclusion is that there was no mirage at all, and that the
* "mountain" was illusory. His drawings show the *lower* limb of the Sun,
* even where it should be occulted by the "mountain" if it were real!
* I conclude that the "dark spots" were either afterimages or bleached
* areas on the observers' retinas. We have no direct accounts from the
* other officers present; they would be unlikely to contradict their
* commanding officer, I suspect.
* Note that Korzenewsky (1923) says the distance claimed here was 1177 km
* but the actual value is just under 900 km.
*
* The title translates as:
*
* "Unusual phenomena of refraction observed in the Japanese Sea."
* "Read at the I.R.G.O. session for the sections of mathematical and
* physical geography, March 11, 1914"
* Reports of the Imperial Russian Geographical Society
*
* Of course the pre-Revolutionary alphabet and spelling are used:
*
* К. П. Іессенъ
* Необыкновенное явления рефракціи, наблюденное въ Японскомъ морѣ
* Известія Императорскаго Русскаго Географическаго Общества
*
*
* Early mention of "Crocker Land" in the London Times
* "Crocker Land" appears 5 times, in passing.
* Dateline is "from our correspondent", New York, July 7 (1908)
* Plans for the "Crocker Land Expedition"
* "It is estimated that not less than fifty thousand dollars ($50,000)
* must be provided for the absolute needs of the expedition, in order to
* enable it to accomplish the valuable results that have been outlined
* above . . . . Subscriptions to the fund are invited."
* At this point, the expedition was to have been led by George Borup,
* then only 5 years out of Yale, with Donald B. MacMillan.
* The start: it is now "George Borup Memorial" with MacMillan leader
* "The original program of work for the expedition contemplated two
* years or three summer seasons in the Arctic, but supplies have been
* taken north which will enable the party to remain three years or even
* longer . . . ."
* The New York Tribune announcement that "Crocker Land" was a mirage
* "The news that the land was not seen . . . where Peary sighted it eight
* years ago, was received yesterday by the American Museum of Natural
* History. The news was relayed . . . through the courtesy of Knud
* Rasmussen" who is quoted from an interview. The word was received
* second-hand from Ekblaw, who met Rasmussen's men while hunting.
* MacMillan's full report "will wait until spring at Upernavik for the
* first Danish boat to convey it to Copenhagen. The report will then be
* cabled to the Tribune . . . probably in April or May. . . ."
* Scientific American reports that the N.Y.Tribune is the "mouthpiece"
* of the Expedition, and reports that the news that "Crocker Land does
* not exist" was in the Nov. 25 issue of the Tribune .
* Donald B. MacMillan's report on the expedition, in HARPER'S
* Contains the first-hand MIRAGE reports.
*
* There's not much of interest in the first installment, except for a
* discussion on p. 654 in which he mentions that he made a point of
* getting rid of "the older and more influential Eskimos, who seemed to
* be very much afraid of walking home in case their dogs should die. In
* a discussion of this kind as to what they should do, the younger men of
* the party listen respectfully to the opinion of their elders and do as
* they advise. Young Eskimos on a long and dangerous trip are much to be
* preferred, for they are fond of adventure and willing to take a chance,
* while the older men wish to make certain of getting home." He then
* says, "From the sixteen Eskimos I picked out seven who appeared to me
* to be of the right stuff and who, I thought, would go the limit."
*
* The second installment tells of reaching "Crocker Land" and contains
* the various well-known (but usually uncited) quotations. Page 924:
* "April 21st was a beautiful day; all mist was gone, the clear blue of
* the sky extending down to the very horizon. Green was no sooner out of
* the igloo than he came running back, calling in the door, `We have it!'
* Following Green, we ran to the top of the highest mound. There could be
* no doubt about it. Great heavens, what a land! Hills, valleys,
* snow-capped peaks extending through at least 120 degrees of the horizon.
* Anxiously I turned to Pee-ah-wah-to, asking him toward which point we
* had better lay our course. After critically examining it for a few
* minutes, he astounded me by replying that he thought it was `poo-jok'
* (mist). Ee-took-ah-shoo offered no encouragement, saying, `Perhaps it
* is.' Green was still convinced that it must be land. At any rate, it
* was worth watching. As we proceeded it gradually changed its appearance
* and varied in extent with the swinging around of the sun, finally at
* night disappearing altogether. As we drank our hot tea and gnawed the
* pemmican we did a good deal of thinking. Could Peary with all his
* experience have been mistaken? Was this mirage which had deceived us
* the very thing which deceived him eight years ago? If he did see
* Crocker Land, then it was considerably more than one hundred and twenty
* miles away . . . ." On the next page he mentions "our almost constant
* traveling companion, the mirage. We were convinced that we were in
* pursuit of a will-o'-the-wisp, ever receding, ever changing, ever
* beckoning." He then quotes from Peary's "Nearest the Pole" book (but
* gives no page reference.)
*
* On the return trip (p. 927): "Throughout the day the mirage of the sea
* ice, resembling in every particular an immense land, seemed to be
* mocking us. It seemed so near and so easily attainable if we would
* only turn back." On p. 928, he is standing on "the very spot" where
* Peary "saw what resembled land. The day was exceptionally clear, not a
* trace of a cloud or mist; if land could ever be seen, it could be now.
* Yes, there it was! It could even be seen without a glass extending
* from southwest true to north-northeast. Our powerful glasses, however,
* brought out more clearly the dark background in contrast with the
* white, the whole resembling hills, valleys, and snow-capped peaks to
* such a degree that, had we not been out there for one hundred and fifty
* miles, we would have staked our lives upon it. Our judgment then as
* now is that this was a mirage or loom of the sea ice."
* Oct. & Nov. issues
* a MIRAGE review article
* A popular and not very critical review, prompted by the article in
* Harper's Magazine debunking Peary's "Crocker Land". The images are
* drawn in both inferior and superior mirages at exactly the same
* distance from the observer as the object. He thinks the intermediate
* images in multiple mirages are all inverted, with only the top and
* bottom ones erect. (p. 519)
* The striations of the Fata Morgana are supposedly "parallel with the
* axes of cylindrical air fields." [sic!] (p. 520)
* The rescue (3rd attempt!)
* Dr. Hunt has made it back, but MacMillan et al. are still isolated in
* northern Greenland. "Direct news" from MacMillan said "that he and
* his companions had only enough supplies to last them until August of
* this year" and that "both relief vessels sent to his aid, the
* George B. Cluett and the Danmark , have failed to reach him and urges
* that a third be sent . . . . This third effort to reach the party will
* cost at least $40,000, provided that the Neptune is able to reach the
* base at Etah . . . . The Committee hopes that in view of the extraordinary
* expenses it will receive substantial financial aid from the public."
* June 15 issue
* Further reports from Dr. Hunt
* The Danmark is stuck in 6 feet of ice and low on coal.
* June 29 issue
* Donald B. MacMillan's book
* This is the full text of the manuscript excerpted by Harper's in 1915.
* Some editor has now tidied up the prose a bit, restraining the somewhat
* breathless pace of the magazine version.
* Dr. Harrison Hunt's story, assembled by his daughter, Ruth Hunt Thompson
* Apparently, the Expedition came near mutiny because MacMillan traded
* necessary supplies to the Eskimos for furs; see p. 71.
* According to Dr. Hunt, MacMillan was irresponsible and had
* "hoodwinked" the Museum. His view was shared by Captain Comer [of the
* Neptune ], who told Hunt's wife that "The whole expedition was founded
* on selfishness. Peary reached a little too far, wished to see land,
* thought he did, and claimed it, resulting in the Crocker Land fiasco . . .
* MacMillan used the expedition as his plaything . . . Dr. Hovey was
* penny-wise and pound-foolish . . . The Cluett was a sailing vessel, not
* fit for a relief ship, and not properly prepared . . . The last two years
* were the hardest, and they were unnecessary." (p.107)
*
* See also p. 207 of T.Forster (1824) for a double lunar crescent
*
* Probably an early BLEACHING observation
* "La journée avait été superbe, le ciel était sans nuages et
* la mer tranquille comme un lac. Le soleil, fort près de l'horizon,
* était rougeâtre comme dans les couchers ordinaires, et son disque
* paraissait à l'oeil nu parfaitement bien terminé. Le bord inférieur
* toucha d'abord l'horizon de la mer, puis le disque s'y enfonc,a peu à
* peu sans se déformer et en conservant sa netteté. Au moment où le
* centre de l'astre atteignait la ligne parfaitement définie qui limitait
* l'horizon de la mer, la partie supérieure du disque, la seule qui fût
* encore visible, se teinta subitement en bleu. Cette teinte nous sembla
* uniforme; elle rappelait exactement le bleu des liquides renferme's dans
* les bocaux que l'on voit ordinairement sur les devantures des pharmacies.
* Ce phénomène persista tout le temps qu'on vit la partie supérieure
* du soleil. Aussitòt après le coucher, l'horizon présenta son aspect
* ordinaire. On distinguait encore, à quatre ou cinq degrés au-dessus
* du point où le soleil avait disparu, trois petits nuages sous-tendant
* chacun un angle d'un ou deux degrés : encore éclairés par le soleil,
* leur lumière était, comme avant le coucher, d'un rouge cuivre très-vif.
* Je n'était pas seul à observer ce curieux spectacle . . . . A quelques
* détails près, nous avons tous été d'accord quand nous avons rassemblé
* nos souvenirs."
* Thanks to Luc Dettwiller for finding this!
* This is the MULTIPLE LUNAR CRESCENT mirage reproduced by Minnaert!
* cf. Clark et al., M.O.1964, and Fultz, 1951.
* Iridescent corona? Or what?
* A curious observation -- not exactly a mirage, though.
* MULTIPLE IMAGE SPLITTING
* Probably not "abnormal refraction" at all, but an AFTERIMAGE report
* "The sun was setting, and about one minute after the sun's upper limb
* had completely disappeared below the horizon five completely circular
* images of the sun were seen to shoot up into the sky at about five
* second intervals."
* The Editor's comment that "it is obviously due to some peculiar form of
* abnormal refraction" is obviously wrong.
* MULTIPLE IMAGES OF THE SUN
* ?? Off-base comment on the preceding report
* Would be an ordinary inf.-mir. sunrise, but 1st drawing makes no sense.
* N.B.: later drawings use circles; so drawings may not be accurate.
* ANOMALOUS COLOR CHANGES of MOON
* "The moon also appeared to be changing colour from the normal yellow to
* green and deep red, and then back again, with a frequency of about 5 sec
* for the complete cycle."
* Otherwise, this would simply be a distorted moonrise.
* DOUBLE IMAGE of MOON
* The colors seen here suggest a grating image. There had been heavy
* rain; could this be a wet grating on a window?
* DOUBLE (??) IMAGE OF SUN
* Surely this can't be right! Because it was taken with a short (45mm)
* lens, and the photo shows cloud strips, I suspect this is simply an
* overexposed image divided by a strip of cloud. It seems impossible to be
* a refraction effect as claimed, at 7 deg. 20 min. above the horizon!
* another fishy-sounding report:
* ". . . disappeared when viewed through a telescope . . . "
* DOUBLE SUN
* "The image was to the right of the true sun, there being no distortion
* of either. This phenomenon persisted for 2 min, after which the image
* gradually elongated in the direction of the true sun, eventually merging
* with it within 1/2 min."
* I think the editor's remarks are off the mark ("lateral mirage").
* Certainly NOT a GF report; the colors sound like mother-of-pearl clouds,
* but the sharp outline is a puzzle.
* The editor's comments, which continue on p.278, are certainly off the mark.
* MULTIPLE LUNAR CRESCENTS
* MULTIPLE LUNAR CRESCENTS
* MULTIPLE LUNAR CRESCENTS
* The drawing is impossible -- something fishy here.
* (A crescent Moon cannot be seen when line of cusps is vertical.)
* Minnaert's review in JOSA
* Minnaert accepts the multiple images as real, largely because of
* Richard's photograph.
* PHONY MULTIPLE LUNAR CRESCENTS
* These multiple images appear to be caused by reflections between glasses
* and eyeball? They are CERTAINLY SPURIOUS, as "This phenomenon could not
* be observed through binoculars or a telescope, it was, however, seen
* through `Polaroid' sunglasses. The phenomenon was also observed, though
* to a lesser degree, on the next five nights."
* The appearance also changed with position of the head, etc.
* MULTIPLE MOONS
* Several disparate phenomena are reported, but treated as if they
* were identical. The original report sounds like a reflection, but too
* few details are provided to identify it. The "answer" provided by John
* Richfield "explains" the report as a mirage, which it cannot be (because
* of the duration of over an hour). Richfield also seems to confuse
* inferior and superior mirages, and understands neither. The second
* "answer", supplied by Hector McDonnell, is clearly a sundog report;
* but he attributes it to "reflection of the Moon and Sun at particular
* angles off the water droplets", which is bizarre nonsense.
* Thanks to Storm Dunlop for the reference!
* MULTIPLE MOONS
* A photograph that most likely shows a ghost image in the camera;
* certainly *not* an atmospheric phenomenon.
* Thanks to Storm Dunlop for a scan of the image!
* cf. photo in Gossard & Strauch book
* For early mentions of "fog", see Marra (1775?), Dickenson (1793),
* Mureau (1798, 1799), Beauford (1802). Kelly (1832), Parnell (1869),
* and Upham (1895).
* also: Schnippel; Bonnelance 1929; P&E pp.184-186 give a bad discussion.
*
* Many lights seen (looming?) from Staten Island at 8 pm, Aug.16
* "All this was seen right side up, and you can imagine how keenly we
* enjoyed it all and longed to reproduce it with a camera. After ten
* minutes during which time we went down to the beach (fourteen feet to
* sea-level), the vision passed suddenly away. At that moment the mirage
* cloud, which was before invisible, was seen. Then we saw in the usual
* place the real lights of Coney Island. This cloud was entirely
* horizontal, very narrow, black, and stationary."
* "The objects of this note are two: the first is to inquire whether there
* is any popular name for the phenomenon, which is, I am told, well known to
* sailors; the second is to ask for references to any measurements of sea
* and air temperatures in conjunction with observations of this character."
* "At about mid-day peculiar cloud effects were noticed on the horizon,
* giving the appearance of a well-wooded tropical coast line. This became
* somewhat indistinct until 16 h. 30 m., when a faint darkness appeared on
* the horizon, increasing in density and in its liquid appearance until
* objects were noticed in an inverted position at an altitude of about two
* degrees [!] above the horizon."
* "FOG" and STRIPES and mirages; TEMPERATURE of air about 4 deg. above water
* ". . . über dem ganzen Horizont ein mehr oder weniger starker
* Dunstschleier,. . . " followed by mirages of ships and looming of lights.
* "Gegen Abend bildeten sich in geringer Höhe über der Kimm die bei
* Luftspiegelungen gewöhnlich auftretenden Streifen, besonders am
* westlichen Horizont, also gegen die Sonne . . . ."
* N.B.: The Gulf of Chihli is the NW arm of the Yellow Sea, usually
* denoted as Bo Hai today, where the Yellow River has its mouth.
* November issue
* Might be REAL FOG in the Straits of Belle Isle?
* "At 8h. on August 17th, . . . although it was perfectly clear and
* sunny where I stood on the shore, there was an extensive layer of fog
* at the scene of operations, about three miles out, and only the smoke
* of the Empress was visible above the layer. . . . I was startled to
* see the Empress above the fog completely upside down with her hull
* pointing skywards and her masts apparently resting on the layer of fog.
* The illusion lasted for about one minute and was perfectly clear in
* every detail when it finally disappeared and the ship came out of the
* fog in its normal position.
* "On a previous occasion I saw three mountains on the Newfoundland
* coast, fifteen miles distant; their summits appeared to be resting on
* the water while the bases were pointing skywards."
* Dec. issue; cited in Hurd's review
* Willis Edwin Hurd's mirage review speaks of "MOCK FOG"
* [Filed separately, because of bulk]
* A review of observations, mostly from the later 1920s and a few from
* the early 1930s; most taken from Marine Observer, but a few "from the
* Hydrographic Bulletin, published by the U.S. Hydrographic Office."
* There is a clear explanation of the terminology, but the observations
* are sometimes misinterpreted, and he seems to count looming in with
* mirages. He unfortunately also says the visibility of objects above
* the horizon when they are geometrically below "is of course an optical
* illusion." [middle of 4th paragraph]
* In the middle of col. 3, he first says ". . . along the line of
* sharpest density change . . . " and then later ". . . a further line of
* density discontinuity." Could this be where O'Connell got the notion
* of "surfaces of discontinuity"?
* The lower part of Col.4 discusses the effects of height of eye, and
* distance to the miraged objects.
* The end of col. 5 discusses "mock fog and haze bands". The "fog"
* aspect is emphasized throughout the paper. He also uses the phrases
* "simulation of fog" and "optical haze".
* The bottom of col. 6 mentions "waterfalls" that are apparently
* either discontinuities in the "horizon", or Lehn's "sea fences".
*
* Cites Barlow (1935, in "Mirage File"), as well as several other
* sources. Because of the large size, this is printed in 8 columns.
* This is known to have appeared on the backs of many Pilot Charts;
* I have seen references to ". . . of the Central American Waters" as
* late as 1944.
*
* THANKS to many people for finding this elusive item! Brenda Corbin
* was instrumental in getting in touch with the NIMA people, who
* eventually came up with it. I had references in the 1930s and '40s;
* but the last paragraph is a post-script saying that Barlow's article
* had appeared "Since preparation of the present . . . article". So the
* writing was evidently done by early 1935. According to Howard J. Cohen
* at NIMA, this was actually published in 1937. Finally, the chart was
* found in a *bound* volume by Albert E. "Skip" Theberge, Jr., at NOAA!
* But, as the format was about 3 ft by 4 ft (that's 75 x 100 cm for the
* metric part of the world), it was too big to photocopy. . . .
* He finally managed to get it photographed and scanned (as a 214 MB
* TIFF file!) Thanks to all these people for their Herculean efforts!
* "When a gray, rather smoky and unnatural-appearing cloud lies along the
* horizon in the early morning, it is generally mirage material. Such a
* cloud will usually form into a clear cut mirage before the morning passes."
* "One fresh morning last autumn . . . a smoky, unnatural cloud graced the
* horizon to the southwest."
* "In the atmosphere at each end of the display the scenery feathered out
* into a misty cloud, which in turn extended ever dimmer into the clear
* sky."
* "The apparent bank of fog was probably an effect of mirage of the horizon."
* Air was 4 F warmer than sea.
* Note: this is shortly after M.O. resumed publication after WW II.
* "From afar, it appeared as if the whole coastline was engulfed in a belt
* of fog with the higher land showing clear."
* "Air temperature 60 F, wet bulb 57, sea 55. The wind was light and
* variable."
* "Approaching Cape St. Francis, a white mist appeared to creep under the
* land and apparently divided it from the sea." See Plate 2, facing p.128
* Here the band is described as a "DUST STORM"
* DOUBLE IMAGES appear in the "dust" band (with its "sharp top outline"!)
* EXCELLENT detailed account of "FOG"
* flanked by rather ordinary mirage reports.
* ". . . what at first appeared to be a fog bank proved to be a mirage.
* With the coastline on the starboard side, distant 15 miles, a dark-blue
* mass, having every appearance of land with undulations as of hills, was
* seen on the port bow from about 4 points to 1 point off the bow where it
* faded into a white band above the horizon."
* ". . . the smoke from these whalers and from our own ship did not rise
* above mast height, but flattened out and hung in the atmosphere in a great
* band about 100 ft above sea level."
* Many nice details of observation, including the effect of eye height.
* ". . . a greenish fog or smoke bank . . . "
* ". . . a heavy whitish mist . . . "
* RED LINE MOONRISE (filed in wrong file here; on same page as previous)
* Seems to be also an example with a dark strip of sky at horizon (false hor.)
* ". . . was obviously in, not on, the water. . . . The moon then rose and the
* red, flame-like light disappeared, to be replaced by two half-moon shaped
* glows in the water."
* Probably belongs in "distorted" file?
* NICE SKETCH
* ". . . the lower ridges were obscured by a grey haze in which appeared
* many inverted icebergs. . . ."
* "All round on the seaward side, there was what looked like a high thick
* bank of fog, which at times resembled a mountainous coastline. This was
* found to have no real existence as it continued to recede as the ship
* advanced."
* NICE DRAWINGS
* ". . . towards sunset, when the sun's upper limb was still well above the
* horizon, an inverted image of this limb, but smaller in area, appeared
* beneath a narrow band of Sc lying very low on the western horizon."
* (Dwg. says "layer of stratocumulus not formed by the spreading of cumulus"
* and it is drawn absolutely flat -- blank strip?)
* NICE DRAWINGS
* "The presence of a heavy grey-brown mist for much of the day gave rise
* to the impression that there was a double horizon. . . . Cliffy Island
* and other small islands appeared very clearly on the `upper' horizon while,
* projecting downwards from them, was a mass of wavy-looking grey-green mist
* and haze." (triple images, a pair between the horizons)
* "Air temp. 81 F, sea 69."
* NICE DRAWINGS of DISTORTED MOONRISE
* (belongs elsewhere, but is filed here because of the next item)
* NEGATIVE DIP
* "During the afternoon the horizon was elevated by between 7 and 10
* minutes of arc above what appeared to be the normal sea horizon.
* All round the horizon there was a band of what looked like fog or mist
* but, on approaching the land, this mistiness disappeared."
* [Note observation of CONCAVE surface.]
* DOUBLE DARK BAND sketched -- just sup. mirages of the ocean?
* ??? This seems to call for a weak duct inside a stronger one.
* "Around the horizon there appeared to be a large bank of fog, topped by
* two thin layers of low stratus. Beneath each layer of cloud there was an
* inverted image of the tanker. . . ."
* ENLARGED DRAWING OF STRUCTURE
* ". . . the horizon appeared to become raised above the sea and separated
* from it by an indistinct misty band. . . . (opposite to the sun) the
* appearance was that of a bank of fog."
* ". . . a layer of haze, dark grey in colour and with a clearly defined
* upper surface, was seen all round the horizon. One ship appeared to be
* completely inverted and an iceberg which was not visible to the naked eye,
* seemed to be hanging upside down from the top of the layer."
* DOUBLED CRESCENT MOON like the one shown in Minnaert (Reimann, 1887)
* (same page as above; belongs in STRANGE PHENOMENA file)
*
* JEAN JACQUES D'ORTOUS DE MAIRAN's first paper on extinction
* He supposes the temperature difference between summer and winter is
* partly due to absorption of the Sun's heat in the atmosphere.
* Curiously, he invokes what is essentially Lambert's [1760] cosine law,
* by introducing the sines of the angles of "incidence" [by which he
* clearly means the altitudes, not the usual angle]; but then decides
* the factor of 3 between the noontime illuminances ought to be squared
* to allow for shadowing by irregularities (pp. 106-107).
* Then he worries about the reflection loss at the upper surface of the
* atmosphere, which he argues might increase with obliquity, as does the
* reflection from water into air as the angle of total internal reflection
* is approached (p. 110). [There is an interesting quote from an earlier
* author about this surface.] But he decides that this is not what happens;
* on p. 111 he argues that the disappearance of the refracted light is
* abrupt. So he thinks the winter attenuation is due to the longer path.
* "Chaque rayon prêt à entrer dans l'Atmosphere, peut être consideré
* comme une balle de Mousquet tirée contre la surface de l'eau d'un
* Bassin, laquelle aura d'autant plus de chemin à faire dans l'eau,
* avant que d'en toucher le fond, qu'elle y fera tirée plus obliquement."
* So he argues that the path is inversely proportional to the sine of
* the angle of incidence, and that the intensity should therefore (!) be
* reduced by this factor yet again. (p. 112)
* But then he has doubts, and wonders about an atmosphere "chargée
* de vapeurs & d'exhalations, telle qu'elle est ordinairement dans toute
* sa partie inferieure, lorsque le Soleil est proche de l'Horison, &
* sur-tout en Hiver." (p. 113).
* He then makes the interesting observation that, at solar eclipses,
* one hardly notices the diminution of the light until the Sun is almost
* completely covered: ". . . j'aurois cru qu'au moins le tiers ou le quart
* de son disque venoit de se découvrir, & ce n'en étoit pas peut-etre
* la milliéme partie." (p. 115)
* On p. 118 he considers the length of the day as a factor. On pp.
* 127-128, he notes that refraction lengthens the day a little; but this
* "est de peu de consequence." [But he thinks it might be important
* near the Poles; and adduces (p. 129) the observations of Bilberg, and
* the Dutch "dans la Nouvelle Zemble."]
* The rest of the paper is an attempt to square his numbers with
* actual temperature measurements. Really, a rather muddle-headed
* attempt all around.
* DE MAIRAN's "Clarification"
* Here he realizes that the extra-atmospheric light of the Sun
* can be extrapolated from two measurements inside the atmosphere.
* Unfortunately, he assumes the light lost is proportional to the
* path length in the atmosphere -- wrong, but not bad near the zenith.
* [But at the horizon, the setting Sun disappears in his model!]
* He assumes a plane-parallel atmosphere (p. 10). He neglects refraction.
* The path lengths are, of course, inversely proportional to the sines of
* the altitudes.
* In section II (p. 12) he considers the curvature of the atmosphere.
* However, he takes the height of the atmosphere to be 15 leagues of
* 2000 toises each, which is much too large; and consequently finds the
* horizontal path to be only 15 times the vertical one. (p. 13)
* "J'ai supposé AT de 20000 toises ou de 15 lieuës, qui est la
* hauteur qu'on donne aujourd'hui le plus communément à l'Atmosphere.
* . . . en faisant AT de 20000 toises ou de 10 lieuës, on trouve AH plus
* de 18 fois aussi grande que AT , . . . & en ne donnant que 1000 toises,
* ou environ demi-lieuë à AT , AH devient environ 74 fois aussi grande
* que AT . D'où il resulte . . . Que lorsque le Soleil est à l'horison,
* les vapeurs doivent nous intercepter une beaucoup plus grande partie de
* la lumiere que ne fait l'Atmosphere, non seulement parce qu'elles sont
* composées de parties plus denses, & peut-être moins transparentes que
* l'air, mais encore que se trouvant d'ordinaire fort près de la surface
* de la Terre, la ligne horisontale qui les travers a un beaucoup plus
* grand rapport avec leur hauteur. . . . Donc des vapeurs qui ne sont point
* du tout sensibles à la vûë, dans le cas des rayons perpendiculaires
* ou peu obliques, doivent affoiblir sensiblement la lumiere du Soleil
* cans le ca de la grande obliquité, & lorsqu'il approche de l'horison:
* ce qui s'accorde parfaitement avec l'experience . . . ." (p. 16)
* On p. 17, he suggests that this obliquity to the vapors might explain
* the variations in the refraction near the horizon as well: "D'où il
* suite que des vapeurs de même nature & de même densité doivent
* donner une refraction horisontale d'autant plus grande, qu'elles sont
* moins élevées, ou que la couche qu'elles forment sur la surface de la
* Terre est moins épaisse."
* PIERRE BOUGUER's first photometric measurements, inspired by de Mairan
* Evidently written by the secretary, rather than Bouguer himself:
* "M. Bouguer, . . . dont nous avons déja parlé en 1721, ayant lû les
* Mémoires donne's par M. de Mairan en 1719 & 1721 . . . , chercha les moyens
* de découvrir par expérience le rapport des diférens degrés de lumiere
* du soleil à différentes élevations . . . ."
* Bouguer's measurements of extinction, and of the ratio of Sun and Moon,
* are reported here. The first date reported is 23 Nov. 1725.
* The copy on Gallica shows 1753 as the publication date on the title
* page; that must be a reprint, as Bouguer corrects a typo on p. 12
* of it in his 1729 "Essai" (below). There are other typos here, too:
* e.g., "lamiere" on p. 11.
* PIERRE BOUGUER's "Essai" (1729)
* Bouguer corrects de Mairan's faulty assumptions, and publishes his own
* airmass table. Only 164 pages are numbered.
* In the Preface, one reads that "C'est Snellius qui a le premier
* découvert la loi de ces réfractions; mais M. Descartes la considérant
* de plus près, en a poussé l'application extrêmement loin." He cites
* de Mairan's 1721 memoir, which inspired his own investigation.
* He also corrects a typo from his 1726 entry in the Histoire .
* de Mairan is cited again on p. 21. He then describes his observations
* of the Moon, and its attenuation at the horizon, "sujet à de très-grande
* varietez;" -- ascribed to "vapeurs", of course. He then endorses de
* Mairan's notion that this is connected with the variations of refraction
* at low altitudes. (p. 25)
* In paragraph VII, p. 28, he compares the Sun with the full Moon, finding
* a ratio of about 300 000.
* His detailed discussion of atmospheric transmission begins on p. 146.
* Here is the origin of the term "air mass". The "Table des masses d'air"
* appears on p. 160. See Bemporad's criticism of Bouguer's derivation.
* The curious remarks about refraction (see next entry) are on p. 151
* here. Most of this atmospheric discussion is reprinted unchanged in the
* 1760 Traité (below).
* PIERRE BOUGUER's "Prize Essay" (1729)
* The first part discusses instruments and their use; the second, the
* necessary corrections to the observations, for both refraction and dip.
* Our concern here is in the corrections, which begin on p.35 [image 46
* of the PDF cited below.]
* Bouguer immediately points out that the angles made by the rays with
* the spherical surfaces of the atmospheric layers are changing with
* distance, and that "cette diversité d'angles d'incidence . . . vient
* principalement de la courbure des couches . . . ." This is why one can
* not apply the famous theorem promoted by Newton in his Opticks to
* the atmosphere. However, on pp. 41-42 a similar invariant for
* the curved atmosphere appears: ". . . les perpendiculaires tirées
* du centre de la terre sur les tangentes de cette courbe, seront
* continuellement proportionelles aux . . . des dilatations . . . ." (This is
* all done in geometric terms, using proportions; but basically he has
* the refractive invariant here.) In the process, he has developed the
* differentials of refraction at each level in the atmosphere.
* Bouguer calls the curved path of the ray "le Solaire", and is
* concerned to find its shape. By taking account of the curvature of the
* Earth and its atmosphere, he assumes that the ray makes the same angle
* at each spherical surface, so that the ray paths are logarithmic spirals
* [p. 43].
* On p. 44, he does the inverse problem, and introduces the sine of the
* apparent zenith distance at the observer, calling it c . This angle is
* the complement of the apparent altitude of the star. [Two decades later,
* he develops this theory more clearly, in his "Second Memoir" published
* in 1753.]
* On p. 47 he writes down an integral for the astronomical refraction.
* His ignorance of the gas laws leads him to believe that the refractions
* are caused by a "refractive material" different from air. [p. 48].
* (His problem is that he expects the refractive index to be the same
* thing as the "refractive power " -- i.e., the refractivity.) So he
* assumes that the sines of the angles are some power of the dilations
* of the air, and that these are proportional to some power of the
* distance from the center of the Earth. But these "dilations" are (in
* modern terms) just inversely proportional to the refractive indices.
* So in fact, this amounts to an assumption that the refractivity is a
* power of the radius, which is equivalent [we now know] to assuming the
* density to be a power of the pressure: he has accidentally adopted a
* polytropic model! So, luckily, he finds his model gives a refraction
* that is a constant fraction of the horizontal arc traversed by the ray
* -- "which is very remarkable!" [p. 49]
* As his Fig. 11 is already too cluttered with about 30 labelled points,
* he removes some of them to make room for more labels, in Fig. 12. Here
* again (p. 50) we have the complement of the apparent altitude of a star.
* So [p. 52] he can construct his refraction table geometrically from
* his logarithmic spiral, given the exponent in the power law. In §.L.
* [p. 53] he explains the details of this process, which requires finding
* the exponent m and the height of the atmosphere. "But nothing is
* easier than to discover these two quantities," says Bouguer [p. 54]
* (though Cassini had a much harder time to do so in a simpler model).
* He has only to fit his model to exact observations of the refraction at
* two different apparent altitudes. He assumes the horizontal refraction
* is one of the known values, and derives an expression for the refraction
* at some other altitude. He then develops an iterative solution for the
* two parameters; this involves the ratio of the sine and cosine of the
* apparent altitude.
* In fact, he calls the sine of the apparent altitude q and the sine of
* its complement (i.e., the zenith distance at the observer) p . (P.54)
* In §.LII. [p. 56] he then shows how to calculate refraction for any
* given altitude -- i.e., how to build a refraction table. He adopts
* 33' for the horizontal refraction, and 2' 12" for 26° altitude.
* These values allow him to compute a new refraction table; he does the
* calculation using 7-place log tables. His new table of astronomical
* refractions is on p. 59 [PDF image 66]. The values are about 10% too
* high, but they do increase steadily near the horizon.
* In §.LVI. [p. 61] he compares his results with the works of Tycho and
* Cassini II.
* On the next page (and Chapter), he discusses the dip of the horizon.
* His dip table [p. 65] is for heights in feet and inches, as the metric
* system had not yet been invented. But on the next page, he points out
* that the ray curvature should decrease the dip slightly. And on the
* next page, he begins the investigation of this correction. And on
* p. 70, he gives a revised dip table.
* Unfortunately, on p. 72 he blames the irregularities of refraction on
* the "vapeurs qui se soutiennent dans la partie basse de l'Atmosphere,"
* and so excuses any discrepancies between his tables and observations.
* Available at https://www.e-rara.ch/zut/content/titleinfo/746433
* NOTE: the text is often obscured by wrinkles in the paper.
* DOI: http://dx.doi.org/10.3931/e-rara-2231
* A MUCH better scan is available at
* https://bvpb.mcu.es/es/consulta/registro.do?id=576360
* Thanks to Luc Dettwiller for this link!
* PIERRE BOUGUER's posthumous "Traité" (1760)
* There is an interesting Preface ("Avertissement") by the Abbé de la
* Caille, who edited Bouguer's work and saw it through the press.
* Bouguer has some curious remarks about refraction (pp. 326-327):
* "Il faut remarquer, que nous négligeons ici la courbure que
* la réfraction fait souffrir aux rayons de lumiere, quoique cette
* courbure les rende un peu plus longs. Il est certain que la réfraction
* astronomique est trop petite , pour que le rapport des sinus d'incidence
* & de réfraction soit conforme à celui des densités de l'air.
* La réfraction suit certainement un autre rapport ; & peut-être
* aussi qu'elle est causée par une matiere particuliere répandue dans
* l'Atmosphere, comme l'ont déja soupçonné quelques Auteurs."
* He then shows how the problem is more complicated if refraction is
* included, so "qu'il est très-difficile de découvrir la relation que
* suivent entr'elles les condensations u de la matiere réfractive; &
* d'ailleurs comme la plus grande réfraction astronomique n'est pas même
* de deux tiers d'un dégré, nous ne rendrions pas notre calcul beaucoup
* plus exact. C'est pourquoi nous négligerons la réfraction . . . ."
* The airmass table is on p. 332. This is available at Gallica!
* Note the English translation by W. E. Knowles Middleton (Toronto, 1961).
* LAPLACE
* Ch. I begins the treatment of refraction; Ch. III is the extinction theorem
* See fuller treatment under "General refraction references".
* FORBES EFFECT -- Forbes's Bakerian Lecture
* See the interesting discussion of Laplace's theorem, and airmass
* generally, in section III, pp. 233-241.
* Forbes says (p.234) that Lambert derived the sec z formula as an
* approximation to the path length in the uniform model, citing p. 393
* of Lambert's Photometria . He has some criticism of L. on p.235.
* Note his treatment of the refraction law on p.237:
* after stating the ratio of sines, he says, "This optical principle
* is derived from experience." [So much for Descartes!]
* Maximil. Julius Maurer's feeble effort
* The historical part is weak, depending mostly on Bruhns for the
* refraction. He shows how little had been done in extinction; this makes
* Bemporad's later remarks about neglect more comprehensible.
* See pp. 21-22 for some snide remarks about Lambert, who thought sec z
* was adequate to 80°. Maurer denotes the airmass function as \Sigma.
* On p.22, he introduces Laplace's theorem, though without understanding
* well the importance of the isothermal assumption.
* On p. 34, there is a curious digression into the arguments of Cheseaux
* and Olbers, and then W. Struve (p. 35) for the absorption of light by
* dust ("fein zertheilter ponderabler Materie im Weltraume") in space. (p.1)
* The more interesting attempt to calculate airmass begins on p. 41;
* but, alas! he adopts an effective height of the atmosphere of 65 km
* (p. 51) and so greatly overestimates the curvature effects. So his
* airmass table (p. 53) gives only 14.961 at the horizon!
* Interestingly, he already (p. 55) points out that the use of
* time and spherical astronomy to calculate ZD gives "die w a h r e n
* Zenithdistanzen der beobachteten Sterne" in Seidel's work.
* This is Maurer's 58-page Inaugural-Dissertation, done under Rudolf Wolf.
* FELIX HAUSDORFF's Habilitationsschrift
* Yes, this is the famous topologist; he started out as a student of
* Heinrich Bruns, writing a thesis on refraction in 1891.
* The style (and notation) is similar to Bruns's: clear, explicit, and
* original. Following Bruns (1891), he immediately notices the important
* product r⋅μ, which he denotes by ν (p.402). He notes (p. 403)
* (cf. Bruns's p.169 footnote) that the refractivity can be proportional
* to [(almost any power of the refractive index) - 1], so that we can
* choose the power to make the integrals easy --- noting that T. Young had
* already made the choice (as he does here) of the first power, in his
* Nautical Almanac tables.
* P.407: he notes there is a formal relationship between the power
* series for refraction and extinction (in terms of powers of tan Z); but
* "Es wäre zwecklos, diese sehr complicirten Ausdrücke aufzustellen,
* da eine Ermittlung . . . aus den Beobachtungen direct . . . wegen der
* Unsicherheit der Messungen im Horizont ganz illusorisch wäre."
* P.408: He describes the airmass "als reducirte Weglänge des
* Strahles" and shows how the extinction can be expressed in magnitudes.
* P.412: He notes that Laplace's approximations have neglected an
* appreciable term, so that the ratio of extinction to refraction contains
* a factor of 1/10 in the zenith, but 1/7 at the horizon. ". . . die
* Laplace'sche Formel . . . die hier dem Gliede erster Ordnung entspricht,
* ist also entschieden unvollständig. Dass sie trotzdem . . . nahezu
* dieselben Resultate ergiebt wie die strengere Formel . . . , liegt daran,
* dass die . . . Coefficienten . . . bis zu hohen Zenithdistanzen einander
* nahezu proportional laufen . . . ."
* P. 417: he recommends a ZD near 87° as a fitting point, in fitting
* 3 parameters (the other two being at Zenith and Horizon).
* P. 420: He notes that twice the path, where the ray is horizontal,
* gives values needed for the theory of lunar eclipses.
* P. 421: note remark on semiconvergent series for Kramp's function.
*
* In Section II (p. 422), he takes a more general approach to resolving
* the discrepancy between theory and observation, by abandoning Laplace's
* proportionality between density (i.e., refractivity) and extinction.
* He notes (p. 423) that this assumption leads neither to closed-form
* expressions nor to a good agreement of theory and observation; while
* taking the absorption as an arbitrary function of height allows a test
* of assumptions about the atmosphere, while operating with closed-form
* expressions instead of series expansions. Here he takes the (nR)
* product as the independent variable!
* This leads (p. 427) to a more general relationship between refraction
* and extinction than Laplace's formula, and one which has "den viel
* weiteren Sinn einer Functionalbeziehung, eines »heuristischen Princips«
* . . . ." (There is still the form of Laplace's relation, though.)
* Semiconvergent series again appear on pp. 431 and 433, as ways to
* evaluate Kramp's (and related) function(s).
* On p. 439, he derives a generalized form of Lambert's extinction
* formula, attributing the simple sec Z form to Pouillet.
* With his decomposition of the extinction into component terms, he
* can represent the observations tolerably exactly -- indeed, I must say
* this is greatly over-analyzing the (rather shaky) data (pp. 440-441).
* On p. 442, he admits as much, pointing out that the result is not
* physically possible: ". . . also die Darstellung der Müller'schen Zahlen
* auf diesem Wege illusorisch ist." (The absorptions become negative.)
* Consequently, in section III (pp. 445 ff.) he investigates what is
* physically possible (i.e., sets limits on the possible extinction
* corrections to the zenith, assuming a positive absorption coefficient
* throughout the atmosphere.) This is done very elegantly by investigating
* the mathematical properties of the extinction integral. The result
* (p.451) is that Müller's values up to 70° ZD cannot represent a
* physically possible run of the absorption coefficient in the atmosphere:
* ". . . die Potsdamer Zahlen wären also in den mittleren Zenithdistanzen
* erheblich zu gross." [So here we see that rara avis , a theoretician
* who actually can detect bad observations!] He tries a more complicated
* (2-term) fit, with similar results: "Diese Zahlen lehren, dass der
* Müller'sche Werth für θ = 75° um mindestens 8 Einheiten der
* letzten Stelle zu gross ist; wollte man ihn beibehalten, so käme man auf
* enorme Widersprüche in den nächsthöheren Zenithdistanzen, z. B. für
* θ = 85° auf eine Mindestabweichung von 0.160."
* Adding more terms to fit more points makes matters worse (p. 452); so
* "Wir schliessen . . . dass eine absolute Darstellung der Müller'sche
* Zahlen durch einen zulässigen Werthverlauf . . . unmöglich ist. . . .
* Auf eine Fehleranhäufung zwischen 60° und 80° liess auch der Gang
* der Widersprüche zwischen M und Laplace schliessen." [ M = Müller ]
* On p. 454, he shows that a fair fit to Müller's data can be obtained
* with a simple rational formula; however, it allows no significant
* improvement. On the next few pages (455-457), he shows that a
* considerably better fit can be obtained by adding a thin absorbing layer
* to the normal atmosphere. This layer turns out to have a height between
* 50 and 170 km; he suggests it could be meteoric dust. [Perhaps it's
* an alias of the ozone layer?] In the subsequent discussion (p. 458),
* he remarks that two acceptable formulae can give quite different zenith
* transmissions; "dies errinnert uns daran, dass Beobachtungen einer
* Station in verschiedenen Zenithdistanzen noch nicht genügen, einen
* Schluss auf die Constitution der Atmosphäre zu begründen, sondern durch
* Beobachtungen auf Stationen verschiedender Meereshöhe zu ergänzen sind."
* He even considers formulae that allow absorption in space, wherein the
* excess of the horizontal over the vertical extinction would be due to the
* one-Earth-Radius longer path length at the horizon! "Derartige Curiosa
* sind bei Formeln mit unendlicher Atmosphäre, die sich der Beobachtung
* einigermassen anschliessen, zwar nicht zu befürchten, wohl aber, dass
* sie den Transmissionscoefficienten zu klein ergeben." (Variants on this
* theme, in which the infinitely thin absorbing layer is replaced by some
* formula with a maximum high in the atmosphere, are also explored.)
* In comparing a number of these variants with observation, he finds
* (p. 463) that there is a tradeoff between the deviations between 60 and
* 80°, and those between 85 and 87.5°: one increases while the other
* decreases. So all these models are so similar that one can only
* conclude "dass die absorbirende Kraft der Atmosphäre zwar zuerst
* mit wachsender Höhe abnimmt, in grösseren Höhen aber (50 bis 200 km)
* wieder merkliche Werthe besitzt."
* In the next section (pp. 464 ff.) he considers additional data, which
* help limit the possibilities. One is the run of the data near the
* horizon: "Für die Horizontalabsorption finden sich aus unseren Formeln
* alle möglichen Werthe bis zu ∞ . . . ." But more important is the
* comparison of data from different heights above sea level. For this,
* he uses Müller's observations from Säntis. These allow some of the
* worst models to be rejected.
* Note: on p. 469, he points out that both Müller's tables and Seidel's
* use true rather than refracted zenith distances as arguments.
* P. 472: at last he comes to Langley's objections (i.e., the Forbes
* effect). He develops this theory in general terms, introducing a
* function s that is the base-10 equivalent of sinh(x)/x. He then
* finds (p. 478) that introducing this effect greatly improves the
* agreement with observation, but without greatly changing the zenithal
* transmission value for integrated light. (Unfortunately, he does not
* cite Forbes's paper.)
* P. 480: "Diese Rechnungen mögen genügen, um zu zeigen, dass man
* mit der Langley'schen Bemerkung in der That einen weit besseren Anschluss
* an die Beobachtungen erzielen kann als durch die Laplace'sche Formel."
* But (p. 481) the zenith transmission for integrated light is always
* close to 0.8, not Langley's 0.6.
* The conclusions of the paper are summarized on p. 481.
* NOTE: This volume is available at Google Books.
* AZEGLIO BEMPORAD's AIRMASS TABLE
* ``Ein mit der astronomischen Strahlenbrechung sehr verwandtes Problem
* ist das der Extinktion des Lichtes in der Erdatmosphäre. Während wir
* aber von Kepler bis Radau eine grosse Zahl von Theorien der Refraktion
* verzeichnen können, fehlt es bis jetzt überhaupt an einer Theorie der
* Extinktion des Fixsternlichtes, welche mit ähnlicher Strenge und
* Vollständigkeit wie die ersteren entwickelt ist. Dies kann Überraschen,
* wenn man die Wichtigkeit und das immer mehr sich steigernde Interesse
* bedenkt, welches die photometrischen Beobachtungen seit Jahrzehnten
* geniessen, und noch mehr, wenn wir die bis jetzt entwickelten Theorien der
* Extinktion mit den umfangreichen Beobachtungsarbeiten auf demselben
* Gebiete vergleichen.'' [1st para. of Intro.!]
* Bemporad, like Forbes, criticizes Lambert (p.8) for his empiricism.
* The historical review is mostly devoted to the isothermal model and
* Laplace's theorem. However, B. shows that the homogeneous model has
* a series expansion in which the second term already has half the size
* of that for the isothermal model (p. 11); thus there is no equivalent
* of Oriani's theorem for extinction.
*
* B. adopts gradient of 6.22 deg/km to at least 9 km (maybe all the way?)
* (n-1)2 = 1.0005864 for 0 C and 760 mmHg
* R = 6377.36 km; g=9.8052m/sec2; p=1013.168 = 760 mm
* finds M(87)=15.364; 88: 19.787; 89: 26.959; 89.5: 32.332; 90: 39.651
* adopts gradient of 6.21 deg/km in summary table (?).
* finds M(87)=15.365; 88: 19.787; 89: 26.959 in F(z) table.
* Published by "W. Valentiner" (Karl Wilhelm Valentiner, says Wikipedia.)
* ROHLFS mentions Bemp. and Schoenberg, calling airmass X(z)
* He gives the airmass integral, and then: "Bemporad [no citation] and
* Schönberg (see Schönberg (1929)) have done extensive investigations
* of X(z), and a Chebyshev-fit to these data up to X = 5.2 with an error
* of less than 6.4 ⋅ 10-4 is given by" a cubic polynomial in sec z.
* "Such a formula should indeed be used in radio astronomy because
* measurements are often made at zenith distances up to 80° (or even
* more!)" [p. 166]
* On p. 168, he gives an expression for the radio refractivity,
* and suggests that an error of 15% would be acceptable, so that "mean
* refraction can be used and this closely resembles the optical refraction.
* Therefore for z < 80°
*
* Δ z = β tan z , β = 1.'50 .
*
* The ratio of radio to optical refraction is . . . 1.56; thus for larger
* zenith distances, optical refraction tables can be used, provided the
* result is correspondingly multiplied." Tsk, tsk.
* My Airmass approximations for geometric ZD
* Eq.(6) is faulty, and should be ignored. And I misspelled Abalakin's
* name.
* L. Kahl Kristensen rediscovers Laplace's theorem and the rational approx.
* with comments on Wittmann's refraction paper. He shows the constancy of
* the ratio r(z)/(M(z)*sin z) for the std. and isothermal models.
* He cites Newcomb's unreliable text for the refractive invariant, and
* uses the old ICAO atmosphere -- which he apparently does not realize is
* different from Bemporad's model.
* Unfortunately, he only fits the Pulkovo table for mean refraction, so
* the claimed high accuracy of the fit is of little practical use.
* Thanks to ADS for making this available! Their scan is better than
* the Wiley one; but Wiley's has OCR'd text, and ADS does not.
* Chambers knows about Laplace's theorem, but . . .
* . . . proposes to use it to calculate airmass for photometric reductions,
* via the Saastamoinen method for calculating the refraction! (pp.142-143)
* There are also some other scary bits, like giving a CO2 refractivity to
* 3 sig. figs. without a dispersion term, and the use of a scale height
* that assumes a fixed water-vapor mixing ratio, and "the local radius of
* the reference ellipsoid" for the radius in calculating h/R . . . .
* [This group's use of square-sided passbands also does not increase
* confidence that they know what they are getting into.]
* Sergey Kivalov's new method of calculating airmass
* Siebren's comment on Sergey's paper
* "Ray tracing by path length is shown to avoid singularities both at
* the horizon and in the zenith. A fourth-order Runge-Kutta numerical
* integration scheme is presented, which treats refraction and air mass
* as path integrals."
* Interesting comparison of choices of independent variables.
* These guys took up my suggestion to show that the "mapping function"
* of the radio scientists is essentially the airmass function.
* Available at: https://doi.org/10.1029/2008JD010176
* Fine REVIEW of 26 airmass approximation formulae
* Jeffrey G. Mangum and Patrick Wallace review refraction and airmass
* for radio astronomers. There is much emphasis on water-vapor effects
* at microwave frequencies.
* They cite my 2004 AJ paper but not the 2006 tutorial paper in Obsy.,
* or the 2008 and 2011 papers by Ígor Rapp-Arrarás and Juan M. Domingo-Santos
* cited above.
* Don't overlook their 2-page Erratum on pp. 500-501, which corrects some
* serious errors in the original paper.
* Cong Qiu and many co-authors compare "mapping functions"
* Here the tilt effect appears as "atmospheric gradients" or "atmospheric
* azimuthal asymmetry" in "gradient models". (See references 49-51 and 61.)
*
* Full list of authors:
* Cong Qiu, Xiaoming Wang, Zishen Li, Shaotian Zhang, Haobo Li, Jinglei Zhang,
* and Hong Yuan
* Available at www.mdpi.com/journal/remotesensing
* DOI: doi:10.3390/rs12010130
*
*
* Logically belongs with the AIRMASS file because of Link's work on both.
*
* Link's thesis on lunar-eclipse photometry: he invents a Biot-like scheme
* He shows very clearly the relation between REFRACTION and AIRMASS:
* refraction is proportional to the integral of a function with respect
* to ρ , but airmass is the same function integrated with ρ dh.
* He shows a graph of his refraction integrand at the horizon.
* The part about refraction is on pp. 89-92. He does the integrals
* graphically!
* Link's "new airmass table" denotes airmass as M
* He uses his graphical method to do the numerical quadratures. The
* atmospheric data are from Humphreys's book.
* Remarkably, there is no mention of Bemporad!
* Available from ADS.
* Link repeats his exposition here, and clearly explains the refr./airmass
* relationship. Fig. 1 shows his airmass integrand for 90 and 84° ZD.
* "La forme générale des courbes . . . montre que la valeur
* des intégrales correspondantes dépend surtout des conditions
* météorologiques dans la basse atmosphère. L'importance des couches
* élevées décroit assez vite pour qu'on puisse les négliger ou mieux
* les remplacer par leurs valeurs moyennes." (p. 166)
* He also suggests that, as a complete atmospheric sounding is needed
* to determine the refraction and airmass near the horizon, "Le procédé
* inverse ne paraît pas impossible à première vue . . . ."
* Cites Tikhov (1936) for large (2°) refractions in winter.
* Again, no mention of Bemporad!
* Available from ADS.
*
* NEWTON
* Book Two, Part III, Prop. X contains the result that in plane-parallel
* media, "the Sum of all the Refractions will be equal to the single
* Refraction which it would have suffer'd in passing immediately out of the
* first Medium into the last." He uses this to derive the "Refraction
* of the Air" from "that of the Atmosphere observed by Astronomers."
* "Based on the Fourth Edition London 1730"; the same passages occur on
* pp. 73-74 of the first edition (1704), which is available at
*
* https://www.google.com/books/edition/Opticks/Oqd3OUaKY0UC?hl=en&gbpv=1
*
* The 1704 edition ends with Query 16 of Book 3, Part I, which is on p.347
* of the Dover edition, and p. 137 of the 1704 edition. After that, the
* first edition contains two mathematical treatises in Latin on third
* order curves, and the quadrature of curves.
* DELAMBRE/Mathieu "Histoire"
* Mathieu edited Delambre's manuscipt for publication, adding extensive
* footnotes and comments of his own, and analysing many old observations
* in the light of current understanding c. 1825.
* Of importance here are the extensive discussions of astronomical
* refraction (indexed on p. xlvi = image 54 of the Gallica PDF); the
* discussion of mirage observations by both Le Gentil and by Mathieu and
* Biot in Mathieu's long footnote on pp. 695-697 (Gallica images 756-758);
* and Mathieu's special "Note" on pp. 774- 796 (images 835-857) discussing
* refraction. The main text ends with Ivory's 1823 work, which was very
* fresh when this was published. The Note refers to Plana's 1823 paper;
* unfortunately, the "Histoire" was published just a year before Plana's
* even more thorough 1828 paper.
* In the mirage discussion (p. 696), Mathieu says: "Ces apparences
* singulières ne sont pas rares dans nos climats, car, pendant
* l'hiver de 1808. je me trouvais à Dunkerque avec M. Biot, et nous
* avons eu ocoasion de voir des effets très variés de réfraction
* extraordinaire. Nous étions presque sûrs de les retrouver quand nous
* nous rendions au bord de la mer, après un abaissement brusque dans la
* température de l'air." On the next page he adds: ". . . et il parait
* bien constant que, quand il a lieu, l'air est toujours plus froid que le
* sol. Les doubles images qui produisent les phénomènes du mirage et de
* la simple suspension peuvent même se former quand les rayons visuels
* rasent de la glace ou de la neige, pourvu que ces corps soient à une
* température plus élevée que celle de l'air."
* Mathieu accepts Arago's spurious "disproof" of Bouguer's observation
* of solar limb-darkening.
* The title page says "Publiée par M. Mathieu", which should technically
* make him the publisher; but in fact he was the editor (as well as a
* co-author!).
* Available from Gallica; the PDF image numbers are larger than the page
* numbers by 61. Gallica's PDF contains the Figures at the end.
* David BREWSTER's "Treatise on Optics"
* Widely cited by later authors; but not entirely reliable. Mirages are
* treated in Chapter XXXI, "On Unusual Refraction", pp. 255-264. He mixes
* in some optical illusions and the Brocken specter; mentions the classic
* examples (Latham, Vince, Monge, Scoresby, Wollaston) without actually
* citing them, and accepts the phony Jurine & Soret "lateral mirage". The
* fata morgana gets a brief summary of Nicholson's translation of Minasi,
* but no citation. He thinks horizontal magnification is "quite possible"
* in mirages, and accepts Monge's "reflecting surface". On p. 263 he says:
* "That some of the phenomena ascribed to unusual refraction are owing to
* unusual reflexion arising from difference of density, cannot, we think,
* admit of a doubt."
* Article in TEATRO UNIVERSALE on mirages, etc.
* Notable for attempts to explain these terms.
* This weekly publication was written for educated general readers,
* bringing them up to date on diverse matters; see the Prefazione
* on p. VII. As the subtitle "RACCOLTA ENCICLOPEDICA E SCENOGRAFICÄ
* indicates, it was profusely illustrated. It ran from 1834-48. The
* printing equipment is described in the Prefazione to Vol. 1, which is
* available at Wikimedia.
* Its publisher was Giuseppe Pomba, who set up the first rotary press
* in Italy. He produced several weekly journals, with the common theme
* of educating the general public.
* The title page says it was published by "una societá di librai
* italiani" (association of Italian booksellers). The Prefazione in
* vol. 5, dated 31 Dec. 1838, is signed by Davide Bertolotti. But Vol. 5
* also shows that Pomba had turned this publication over to Baglione
* in 1838. Bertolotti also signed poems in the Dec.1, 1838 issue,
* and in some 1839 issues. But by 1840, another publisher had taken
* over, and Bertolotti had disappeared from its pages.
* Bertolotti mentioned (in his Preface to vol. 5) that "the illustrious
* Prof. Brugnatelli" had contributed many articles on "physical geography"
* to the Teatro ; so perhaps this item is one of them?
* Google Books has vols. 5 (1838) and 6 (1839) bound as one volume.
* This is the 27 Luglio issue. This article is illustrated with a large
* wood engraving of "Fenomeno del Miraglio nelle pianure del Messico."
* Thanks to Marcella Pace for pointing out this article!
* GRUNERT/CLAUSIUS review
* Good explanation of German terms (Kimmung = looming; Seegesicht =
* inferior mirage) and sloppy usage.
* In the third number, a few pages earlier, Grunert himself comments on
* Gergonne's theory of mirages (p. 308), which he extends; and on
* Biot's monograph. In particular, in section 24 (pp. 348-357), he
* discusses the elliptical locus of the vertices of the rays, and the
* relations [later rediscovered by Tait!] between them and the nature
* of the images. This 3rd number is dated 1849; it begins on p. 267.
* The 4th number (1850) is by Rudolf Clausius. He begins with the
* apparent shape of the sky; evidently this was the model for Pernter &
* Exner's discussion. Then comes extinction, and the light of the sky,
* followed by a long discussion of twilight.
* Refraction begins on p. 399. He discusses the horizontal refraction,
* and the flattening of the Sun and Moon there. The interesting part
* begins on p. 401, with "Ungewöhnliche Senkung und Hebung des
* Horizontes." He mentions "sinking" observed in the Gulf Stream, and
* cites Latham's observations in the English Channel. "Man hat für das
* ungewöhnliche Sichtbarwerden ferner Gegenstände auch im Volke eigene
* Ausdrücke. Bei den englischen Schiffern heisst es looming , und bei
* uns K i m m u n g , welche Namen freilich auch oft für andere
* verwandte Erscheinungen gebraucht werden." (p. 404)
* Then come mirages. Of Minasi's account of the Fata Morgana, he says:
* ". . . hat seiner Beschreibung, die aus mehrfacher eigener Anschauung
* geschöpft sein soll, offenbar Manches aus seiner Phantasie beigemischt."
* Then he brings in Monge. He notes that inferior mirages were long known
* to sailors as "Seegesicht". He cites Büsch's "Tractatus duo". (p. 407)
* and Woltmann's observations, too. "Aber vollständig entwickelt ist sie
* erst von Biot".
* Then comes the passage referred to by Möbius (1925): ". . . dem
* beschriebenen Vorgange eine gewisse Aehnlichkeit mit der
* R e f l e x i o n des Lichtes giebt, obwohl er von dieser seinem
* Wesen nach ganz verschieden ist, und nur auf Brechung beruht." Here,
* he adds a footnote that mentions total reflection. (p. 409)
* Vince and Scoresby then appear. The mirage discussion ends on p. 419,
* where he goes on to discuss the twinkling of the stars.
* This is "Erster Theil, Viertes Heft" of "Beiträge zur meteorologischen
* Optik und zu verwandten Wissenschaften. In zwanglosen Heften
* herausgegeben von Johann August Grunert"
* = Beiträge z. meteorol. Optik. I. 4.
* available at https://archive.org/details/beitrgezurmeteo00claugoog
* (but of course the plates are suppressed).
* CLARKE's important "Geodesy" text (1880)
* Colonel Alexander Ross Clarke, C.B.
* The first page of the Preface says:
* "The Essay entitled 'Figure of the Earth,' by Sir G. B. Airy,
* in the Encyclopedia Metropolitana, is the only adequate treatise on
* Geodetic Surveys which has been published in the English language, and
* though now scarce, it will ever remain valuable both on account of the
* historic research it contains, and the simple and lucid exposition of the
* mechanical theory there given. Since the date of its publication however
* have appeared many important volumes, --- scientific, descriptive,
* official, --- such as Bessel's Gradmessung in Ostpreussen; Colonel
* Everest's Account (1847) of his Great Arc; Struve's two splendid volumes
* descriptive of the trigonometrical chain connecting the Black Sea with
* the North Cape; the Account of the Triangulation of the British Isles;
* the Publications of the International Geodetic Association; recent vo1umes
* of the Mémorial du Dépôt Général de la Guerre; the Yearly Reports
* of the United States Coast and Geodetic Survey; the current volumes by
* General Ibañez, descriptive of the Spanish Triangulation, so remarkable
* for precision; and last, though not least, the five volumes recently
* published by General Walker, containing the details of Indian Geodesy."
* The first chapter is a fine HISTORICAL REVIEW, starting with Snellius
* and Picard. Ch. II is Spherical Trigonometry; III is Least Squares.
* The radius of the (assumed) spherical Earth appears first; dip is in
* the fourth sentence, and the Mount Edgecombe observation is cited as an
* early attempt to measure it. [According to Airy's article "Figure of
* the Earth" in vol. 5, pp. 175-240 of "Encyclopedia Metropolitana" (1845),
* this was measured by Edward Wright, and published by Richard Norwood in
* "The Seaman's Practice, contayning a fundamentall Probleme in Navigation
* experimentally verified, namely touching the Compasse of the Earth and
* Sea, and the Quantity of a Degree in our English Measures, &c." (1637).
* Airy gives the location as "Mount Edgecumbe".]
* A nice feature of the historical introductory chapter is that it
* provides the geodetical connection among the works of the Cassinis,
* the French surveys in Peru and Lapland, and later workers, and thus
* puts into context the works of people like Bouguer, de La Condamine,
* Maupertuis, General Roy, Von Zach, Delambre, Mechain, Legendre, and
* later workers like Tobias Mayer, Struve, Biot and Arago, and Bessel,
* and instrument makers like Ramsden. Finally, on p.27, Colonel Everest
* appears. So, all the scattered studies that seem like isolated details
* in this bibliography are brought together in a grand historical narrative.
* Talcott's Method is discussed on pp. 186-187.
* Refraction is mentioned on p. 2, as "a phenomenon of variable and
* uncertain amount", but is not examined until Ch. XI, "Heights of Stations"
* (p. 280), where Bauernfeind's 1866 papers are cited. Here we find:
* "The amount of terrestrial refraction is very variable and not to be
* expressed by any simple law: the path of a ray of light, inasmuch as it
* depends on the refractive power of the atmosphere at every point through
* which it passes, is necessarily very irregular. This irregularity is
* very marked when the stations are low and the ray grazes the surface of
* the ground. In the plains of India it has been observed that the ground
* intervening between the observer and the distant signal, from being
* apparently convex in the early part of the day, changes gradually its
* appearance as the day advances, to a concavity --- so that at sunset
* the ground seems to slope up to the base of the signal tower which in
* the early morning was entirely below the horizon."
* Here (p. 281) are cited the "Great Trigonometrical Survey of India"
* and Hossard's paper in Mém. du Dépôt Gén. de la Guerre, vol. ix, p. 451
* (1853). Unfortunately this seems to be where the mistaken notion that
* the refraction is least in the afternoon came from. Note that his
* "coefficient of refraction" is about 1/14. not 1/7.
* On the next page are some British measurements, of which the most
* discrepant was made at Ben Nevis, where "for a fortnight --- when
* the greater part of the observations were made --- the state of the
* atmosphere at the top of the hill was most unusually calm, so much so,
* that a lighted candle could often be carried from the tents of the men
* to the observatory, whilst at the foot of the hill the weather was wild
* and stormy."
* On p. 283 a distinction is drawn "between rays which cross the sea and
* those which do not." (A larger coefficient of refraction is found across
* water.)
* HELMERT's "Geodesy" text
* The refraction details are all in Part 2 here; Part I was called
* "Einleitung und I. Teil: Die mathematischen Theorieen". (Notice the
* curious change in spelling; the body of the text wavers between keeping
* and dropping the "h" in both volumes.)
* In the Vorwort, Helmert says: "Bei der Theorie der Refraktion
* im achten Kapitel habe ich mich darauf beschränkt, solche Formeln
* abzuleiten, welche voraussetzen, daß das Gesetz für die Änderung der
* Temperatur mit der Höhe durch eine stark konvergente Reihe nach Taylor
* darstellbar ist. Für diesen Fall sind die Formeln allgemein gültig,
* so daß man die Konstanten aus zweckmäßig angeordneten Beobachtungen
* bestimmen kann. Ein Zahlenbeispiel ist den von v. Bauernfeind
* publizierten Messungen entnommen." (p. VIII)
* The refraction discussion really begins about p.502; but is sparse
* until after p. 550, where "Lateralrefraktion" is mentioned. (This is the
* skewness effect due to the polar flattening of the ellipsoid.) And
* refraction in altitude begins on p. 553, where the familiar expression
* (dn/n) tan z appears. The invariant is on p. 554. But this good start
* is derailed by replacing cot z with sqrt(1 - sin2 z). "Von dieser
* Gleichung, welche schon Laplace kannte, ausgehend, . . . " (But of course
* Newton and several others had it before Laplace.) Then comes the
* Reihenentwicklung. . . .
* P.555: here, kappa is the symbol for -(r/n)(dn/dr), and I hoped he
* would go on to pre-empt Auer & Standish; but no. On the next pages we
* find the surveyors' refraction coefficient k derived. But this all
* assumes that the expansion of κ in terms of its height-derivatives
* converges sufficiently rapidly. On p.556, he says: "Selbstredend ist
* zur praktischen Brauchbarkeit der Formel (7) eine so rasche Konvergenz
* erforderlich, daß zum mindesten die nicht angesetzten Glieder unerheblich
* sind. Inwieweit dieses für einen thatsächlichen Luftzustand der Fall
* ist, kann aber nur die Erfahrung zeigen." [Modern high-resolution
* observations of boundary-layer fine structure do not support this.]
* TILT discussion:
* The skewness effects are discussed on pp. 564 ff.; see references
* cited on p. 565. Of more interest is the discussion of deviations of the
* surfaces of constant density from the "Normalform" due to irregularities
* in the distribution of heat and pressure in the air (p. 566), especially
* those due to sloping ground. If the isopycnic surfaces are inclined, the
* differential of refraction must have the angle between the ray and the
* local normal to these surfaces instead of the zenith distance. (p. 567)
* He denotes the tilt angle as ν, which he imagines might be as big as
* several degrees. (p. 568) But he notes (p. 569) that abnormal lateral
* refractions rarely exceed a few arc seconds, so the actual tilts must
* be small.
* WILLIAM CHAUVENET's treatment
* This used to be the standard textbook of astronomical refraction; it's
* now completely obsolete. Likewise, the treatment of Least Squares in
* Vol. II (especially "Chauvenet's criterion" for the rejection of data)
* is frowned on today, now that we have better methods of "robust
* estimation". However, he does provide an early description of Talcott's
* Method for measuring latitude; cf. Clarke (1880).
* VALENTINER/OPPOLZER
* Oppolzer appreciates the height distribution; see p. 562, where he cites
* Fabritius. There is a good section on TILT of layers, pp. 577-580.
* He also discusses nocturnal inversions (pp. 588-589) and dispersion, and
* has a section on pavilion refraction. Very good!
* The series is "Encyklopædie der Naturwissenschaften"; this is
* "III. Abtheilung. II. Theil: Handwörterbuch der Astronomie".
* Google Books has a good scan of this volume.
* NEWCOMB
* Surprisingly full of errors. The numerical error I found here in my
* 2004 AJ paper is on pp. 217-219. In any case, his treatment, based on
* Radau's series expansions, is completely obsolete today.
* The clarity is not helped by the typography. The publisher chose to
* use a printer in Glasgow (!) -- presumably to save cost in printing.
* That printer used fonts in which the Greek α is very similar to the
* Italic a . In addition, Newcomb used a local constant factor denoted
* by a Roman "a" in some of the equations for refraction.
* The start of each signature is marked by "N.S.A." at the foot of the
* page, which presumably meant "Newcomb's Spherical Astronomy" to the
* binder. It's a bit distracting, as this footer is not separated from
* the body type by leading, but is just the last line printed.
* The scan of this volume in Google Books duplicates some of the later
* pages: pp.356-391 appear twice; next come pp. 392-395, which are then
* followed by an additional copy of pp. 326-444 (the end of the book).
* So pp.356-391 appear three times altogether, and 326-355, twice.
* W.W.Campbell's 20-page biography of Newcomb is in Mem.N.A.S. 17 (1924)
* BEMPORAD's Encyclopädie der Mathematischen Wissenschaften article
* This review begins with a table of contents, followed by the bibliography.
* Bemp. explicitly refers to Bruhns, saying that his list extends and
* continues that of Bruhns. The references are blessedly complete!
* Unfortunately, because of the reliance on Bruhns, Ivory's warnings
* about convergence are ignored here. So the development uses the old
* expansions in odd powers of tan Z.
* The super-adiabatic lapse rate of Laplace's model is mentioned in note
* 24 on pp. 305/6. The paragraph suggesting plain mechanical quadrature
* would be better is in the middle of p. 313; cf. n.4, p.294.
* The publication date is uncertain; the title page of this volume says
* "1905-1923". Bemporad's contribution is dated December 1907, so
* the actual publication date might have been 1908.
* [See the review article about the Enzyklopädie by W. van Dyck
* in Jahresbericht der Deutschen Mathematiker-Vereinigung 17, 213-227
* (1908) for an overview -- available from Digizeitschriften, at
* http://digizeitschriften.de/home/zeitschriften/ ]
* A digital version is available at SUB Göttingen. Its Inhaltsverzeichnis
* shows that in section A (Sphärische Astronomie), chapter 3 (Geographische
* Ortsbestimmung, nautische Astronomie) by C.W.Wirtz has a section V.,
* Nautische Astronomie, with subsection 38. "Die Kimm und ihr Verhalten"
* (p. 139) that might also be of interest. These PDFs have high-quality
* page images, but are not searchable; but tesseract handles them well.
* Bemporad's chapter is number 6.
* BEMPORAD's German Encyclopedia article translated into French
* The sub-title says "Exposé, d'après l'article allemand de A. Bemporad
* (Catane) par P. Puiseux (Paris)"; I give both, but it's mostly Bemporad.
* The very first footnote gives 5 references on atmospheric dispersion.
* And (pp. 15-16): "A nos yeux il est beaucoup moins important d'insister
* sur les artifices de développement que de bien caractériser les
* différentes hypothèses. Il y a en effet une méthode (la quadrature
* mécanique), qui, dans toutes les hypothèses, conduit également vite
* au but, c'est-à-dire à la connaissance de la réfraction théorique."
* There is a succinct discussion (pp. 16-17) of the different formulae
* linking the density to the refractivity, pointing out who has used which
* ones, and concluding that the simple Gladstone-Dale formula is as good
* as any. "On devra donc, dans les théories de la réfraction et de
* l'extinction, choisir la formule la plus avantageuse au point de vue
* analytique . . . ."
* Pp. 23-37 have a nice historical summary of the models of Cassini,
* Tobias Mayer, etc. On p. 28 is pointed out that Laplace's formula gives
* a slightly super-adiabatic lapse rate at the surface. This is a much
* clearer review of the various theories than Bruhns's, with the further
* advantage that the works of Bessel and Radau are included. Bauernfeind,
* Schmidt, Gyldén, Oppolzer, and Bruns are given rather short shrift.
* At the end of this review section (p. 37) is the punch line:
* "Quand on réfléchit à la peine qu'ont demandée les developpements
* analytiques des théories de la réfraction, et notamment les plus
* complets de ces développements élaborées par H.Gyldén et R. Radau ,
* on a le droit de penser que la réfraction astronomique s'obtiendra plus
* aisément par un simple calcul numérique (quadrature mécanique), qui
* tiendra compte directement des donées de la physique de l'atmosphère."
* On pp. 37-50 the refraction integral is developed according to the
* more important theories. The extinction is treated on pp. 58-67.
* The title page says "Publiée sous les auspices des académies
* des sciences de Göttigue, de Leipzig, de Munich et de Vienne avec
* la collaboration de nombreux savants. Édition française rédigée
* et publiée d'après l'édition allemande sous la direction de Jules
* Molk, Professeur à l'Université de Nancy. Et pour ce qui concerne
* l'astronomie sous la direction scientifique de H. Andoyer Professeur à
* l'Université de Paris. Tome VII (premier volume), Astronomie Sphérique.
* Rédigé dans l'Édition allemande sous la direction de K. Schwarzschild
* à Potsdam." The original German edition appears to be:
* Besondere Behandlung des Einflusses der Atmosphäre (Refraktion und
* Extinktion), Enz. der math. Wiss. 6, part 2, (Teubner, Leipzig, 1907)
* My photocopy lacks pp. 21, 51-57.
* Sir ROBERT BALL
* Very readable treatment; derives the usual approx. from Cassini's model
* on pp. 125-128. Unfortunately, an excessive number of approximations
* is used, so the result is not very accurate. However, there is a neat
* proof of Oriani's theorem on pp. 123-124 (though Oriani is not mentioned).
* Theoretical treatment of atmospheric optics; no GF coverage
* There are some useful remarks on mirages:
* "Da plötzliche Übergänge von n , wie zu festen order flüssigen
* Mitteln, hier nicht anzunehmen sind, dürfte man wohl, streng genommen,
* nicht, wie es oft geschieht, von Totalreflexion und Luftspiegelungen
* sprechen, wenn auch eine Analogie zweifellos besteht." (p. 500)
* (Here he cites Claudius [sic; he means Rudolf Clausius, in Grunerts
* Beiträge zur Met. Optik ], 1850, for similar remarks.)
* This is the only work to cite Brandes's article in Gehlers
* Physikalisches Wörterbuch , so far as I know.
* THANKS to Shaun Hardy for supplying a copy of this!
* After much searching, I found that this author is Alfred Willy Möbius
* = Wilfried Möbius (1879 - 1964). See
*
* https://de.wikipedia.org/wiki/Willy_M%C3%B6bius
*
* He published a few papers on the theory of the rainbow, some of which are
* cited in his Encyclopedia article, which seems to be his last publication.
* Most were published by Teubner, beginning with "Einführung in die Optik
* der Atmosphäre" (1907).
* Review article in 1944 "International Hydrographic Review"
* This covers both REFRACTION and DIP, and cites many obscure tables.
* It is available at the University of New Brunswick library website:
*
* https://journals.lib.unb.ca/index.php/ihr/issue/archive/2
*
* The coverage is much more complete (up to 1944) than the recent
* review article by François Mignard in C.R.-Physique (2022). On the
* other hand, this review contains some typos, such as "Bompard" for
* Bemporad, and "Delamare" for Delambre, so that one wonders about the
* accuracy of the discussion.
* On the title page of this article, the author is "Ingénieur Hydrographe
* Général P. de VANSSAY de BLAVOUS, Director". He is just "P. de Vanssay"
* in the IHR archives. On the front matter, he is listed as one of the
* two Directors of the International Hydrographic Bureau (which is now
* the International Hydrographic Organization, whose website is at
*
* https://ihr.iho.int/ .
*
* This issue is No. 39 in the series published by the IHB in Monte-Carlo,
* Monaco, and dated August, 1944. The title page simply says "Hydrographic
* Review".
* GENERAL REFERENCES before 1951
* DANJON
* Chapitre IX is devoted to refraction, including DIP and MIRAGES.
* Dispersion and chromatic scintillation are mentioned, but not green flashes.
* Thanks to Fred Talbert for reminding me of this!
* VASSY
* Étienne Vassy was primarily interested in the upper atmosphere, which
* explains the chapters here on the ionosphere and sound propagation.
* He is mostly remembered today for his work on ozone in the 1930s.
* Section 4 of Ch. I is "Influence de la dispersion; le rayon vert."
* Even at this late date, he says Julius's anomalous-dispersion theory is
* one of two possible explanations; though he points out that Danjon &
* Rougier's work refutes it.
* Having seen the phenomenon repeatedly at a single location during one
* week(!), he thinks it is a result of thermal inversions. He also has
* the Byrd story wrong ("le premier jour de l'apparition du Soleil après
* la nuit polaire. . . "). (p. 15)
* On p. 16, he worries about the variable (and overly long) duration.
* But he thinks this can be explained by the effects of "fluctuations
* notables d'indice le long des rayons . . . si l'obstacle derrière lequel
* disparaît le Soleil est surmonté d'une couche d'air dont l'indice
* commence par croître avec l'altitude."
* He also worries about the sudden change of color, which he attributes
* to the rain-band of water vapor.
* On p. 40, he attributes the distortions of the low Sun to variations
* of index along the trajectory. Much of his mirage discussion is based
* on Flammarion.
* Hardly half a dozen references are cited in the whole book!
* [Tome I was on emission phenomena.]
* SMART
* The classical textbook on traditional spherical astronomy.
* Robert G. FLEAGLE and Joost A. BUSINGER
* Shows a simplified PALM-TREE diagram, with the usual error (p. 296)
* (Ironic, in view of Businger's later importance for inferior mirages!)
* Mirages get only a page here; GF gets one sentence (p. 358, 2nd ed.).
* The Second (1980) edition is on a Ukrainian Website or Scribd; see p. 356
* WOOLARD & CLEMENCE
* General: Chapter 5; DIP, SUNSET in Chapter 10,
* "Determinations of position in the local reference system"
* Specific: a very superficial mention of refraction near the horizon on
* p. 88, listed in the index; but citing few references, and neglecting
* the works of Fletcher, Sugawa, and many others.
* KOLCHINSKII emphasizes issues omitted from the regular texts
* After pointing out the need for refraction of objects within and near
* the limits of the atmosphere, he briefly reviews the literature.
* There are several interesting items in his bibliography, especially
* dealing with refraction near the horizon, in the polar regions, etc.
* Pp. 11-12 have a clear summary of Emden's polytropic model, and give
* his series-expansion terms.
* Pp. 13-14: after describing the tables of Link & Neuzil in BAC (1958),
* he notices that their extreme values at the horizon strongly violate
* the usual refractivity scaling (from T and p values). Then (p. 14):
* "Thus, the dispersion between the refraction at the horizon, calculated
* by [refractivity scaling] and obtained by numerical integration, proves
* to be highly significant. It indicates that in this case the upper layers
* of the Earth's atmosphere influence the value of the refraction integral."
* Pp. 14-15 describe Fuss's observations at Pulkovo, which he attributed
* to a low-lying inversion; but K. says that Bauschinger, and also
* Banakhevich, showed this was insufficient. The discussion of large
* refraction near the horizon continues on pp. 16-17; he seems to consider
* this normal phenomenon "anomalous" simply because it is not in the
* standard tables.
* On pp. 18-19, he discusses TILT of the layers, with several references.
* At the end of the Conclusion, p. 40, he raises the issue of using
* terrestrial refraction to estimate temperature gradients, as suggested
* by Fesenkov -- cf. Faye!
* Martin Hotine's "Mathematical Geodesy" reference (1969)
*
* This work introduces the use of tensor calculus to geodesy; see the
* Preface, starting on p. x. TERMINOLOGY and notation are discussed on
* p. xiii. He does not clearly explain his use of ambiguous terms; it
* appears from context that he uses "altitude" to mean height above sea
* level most of the time, but does refer to "altitude and azimuth" on
* p. 251. He uses "height" to mean "height above the reference surface"
* (which is usually the geoid); see p. 233 for "geodetic heights", and
* also the discussion of sign conventions on p. 70.
* Users of GPS will be amused at the remark on p. 147: ". . . relativistic
* effects . . . are unlikely ever to be significant in the case of near-Earth
* satellites."
* Chapter 24 (pp.209-) is "Atmospheric Refraction". Here the refractive
* index is µ. The refractive invariant for the spherical case is derived
* on p. 211. The discussion is basically in terms of geometrical optics:
* he assumes rays, point sources, and the like.
* A notable comment on p. 214 says: "One possible assumption is that the
* model atmosphere is in static equilibrium , which might be approximately
* so in settled weather conditions during the afternoon. This would mean
* that the isopycnics --- or surfaces of equal density --- which are nearly
* the same as the surfaces of equal refractive index, are gravitational
* equipotentials; the gradient of (In µ) is accordingly in the direction
* of the astronomical nadir." But he then assumes the isopycnics are
* all surfaces of constant gravitational potential, "so that the zenith
* distances are all unrefracted." So tilt is neglected. Then the gradient
* of refractivity "will not usually differ from an exact gravitational model
* by more than a few minutes of arc."
* On p.215 we see that geodesists call vertical angles "elevation"
* (corresponding to the astronomer's "altitude".) Footnote 4 there
* discusses the surveyors' "coefficient of refraction". We also have the
* circular-ray approximation. Then the elegant mathematical formalism is
* wasted, and we are back to Helmert.
* Fortunately, this oversimplification is relaxed on the next page, where
* the equation of state is modified to include the water-vapor partial
* pressure. Here the old "3/8" becomes 0.37803. The refractivity of air
* is taken from Edlén's 1966 formula and Barrell & Sears. The group
* velocity finally appears on p. 217. The radio refractivity is the old
* Essen & Froome value with no dispersion.
* The discussion of lapse rates is quite primitive. On p. 221 he does
* find that the rays are straight in dry air for a lapse rate of 0.0334 °C.
* per meter. On the next page, he says the adiabatic lapse rate is "almost
* double what is usually found during the period of minimum refraction from
* reciprocal vertical angle measurements." [Monin and Obukhov published
* their paper in 1954, 15 years before this was published.]
* Astronomical refraction begins on p.223. "A good historical summary
* is given by Newcomb." [ouch!] Garfinkel's works are cited, too. The
* refraction integral is given with d(ln µ) as the variable of integration;
* but no details are offered. Parallactic refraction is treated crudely
* in section 69. Early attempts to measure terrestrial refraction with the
* two-wavelength method conclude the chapter.
* This is ESSA Monograph 2. Its analyses (but not its obsolete numbers)
* are still widely cited by geodesists.
* for DISTORTED SUN, see Fig. 1.2.23, p.49
* AIRMASS & REFRACTION TABLES for std.atmospheres
* ``Temperature inversions . . . occasionally give rise to abnormal effects of
* refraction. . . . The effects are transient and variable, and there is little
* point in attempting to work out an exact theory for them. . . .'' (p.19)
* NORTON'S STAR ATLAS
* The 17th edition (1986) is the same as here.
* A longer but less accurate account is on p. 38 of the 15th ed. (1966).
* Cassini's "formula" given
* AIRMASS & REFRACTION in Chapter 7, "Astrometry through the atmosphere"
* GREEN -- Ch. 4, esp. pp. 87-93
* Table 4.1 (p. 91) "gives approximately the amount of refraction taking
* place above the level in question, for a source at zenith distance
* 45°."
* 2nd EXPLANATORY SUPPLEMENT
* Recommends the Auer-Standish method to calculate refraction, using the
* Hohenkerk-Sinclair (1985) computational scheme.
* not a book, but a textbook-style tutorial article; so placed here
* Caution: fails to mention the tilt effect, so is incomplete.
* Craig F. Bohren and Eugene E. Clothiaux's textbook on RT
* Chapter 4 on Radiometry and Photometry is a nice review of these
* quantities and their units, with an introduction to color science as
* well. But Ch. 8 on Meteorological Optics (p. 397) is our main interest
* here. especially §8.3 on atmospheric refraction (pp.418-426), which
* touches on mirages and GFs.
* The treatment is quite limited: only the flat-Earth mirage model is
* treated, and only Cassini's uniform model is used for astronomical
* refraction. Because dip is ignored, "Fraser's Theorem" is taken to
* imply that the serrated Sun at the horizon must be due to "horizontal
* variations of the refractive index" (p. 425).
* Unfortunately, the uniform model leads to large errors in the
* flattening of objects at the horizon and the width of the green rim.
* No mention of Biot, who did better.
* §8.3.3 (pp.425-426) treats green flashes, pointing out that the
* atmosphere can magnify the green rim. But the various forms are not
* mentioned. Overall, good on the fundamentals, but lacking in depth.
* The Special Issue of C.R.-Physique on atmospheric refraction
*
* Published online at
*
* https://comptes-rendus.academie-sciences.fr/physique/item/CRPHYS_2022__23_S1/
*
* That link shows the Contents of the whole issue. Its Foreword is at
*
* https://comptes-rendus.academie-sciences.fr/physique/item/10.5802/crphys.132.pdf
*
* or https://doi.org/10.5802/crphys.132
*
* This Foreword briefly enumerates the articles in the Special Issue.
* The emphasis is mainly pedagogical and historical, so the articles are
* reviews rather than technical advances. The Foreward is in both French
* and English; most of the articles are in French, with English abstracts.
* I list here some of the more general articles. The more technical ones
* are distributed in this bibliography to their most relevant positions.
* Also, I omit several contributions that deal primarily with "seeing" and
* other effects of turbulence.
* Although the date of the issue is 2022, most of the papers were not
* actually published until 2023.
* François Mignard's review of refraction tables (and how to compute them)
* This starts out looking like a more expanded version of my own paper
* (see below); but it has considerably more numerical detail. There are
* some interesting variations on Cassini's model.
* However, there is also much emphasis on the tangent series; and some
* peculiar omissions: no mention of Flamsteed's connection to Newton's
* table; considerable discussion of how to evaluate integrals, but no
* mention of S.Y. van der Werf's papers; considerable use of polytropic
* layers, but no mention of Emden; etc. In discussing Newcomb's book, he
* notices that the numbers don't agree with the analysis, but fails to
* identify the exact error in Newcomb's numerical work -- which is pointed
* out in my AJ paper, which he cites. He also has the title of Newcomb's
* "Compendium" wrong in the text (but right in the Références).
* On the other hand, he uses Ciddor's dispersion formula, and points out
* the unrealistic nature of the Standard Atmosphere. And Fig. 22 shows an
* actual sunrise sequence (affected visibly by the nocturnal inversion).
* So, a mixed bag. Read with caution; refraction is not his specialty.
* Published online: 25 May 2023 at: https://doi.org/10.5802/crphys.123
* DOI: doi:10.5802/crphys.123
* Luc Dettwiller's classification of refraction phenomena in CR-Phys.
* Largely a descriptive summary of terrestrial refraction phenomena,
* like a shortened French version of Humphreys (1940) brought up to date
* with recent references.
* There is a nice discussion of the virtual images percieved by the eye,
* and their apparent positions (even when the physical position of the
* real astigmatic image lies behind the eye).
* Luc makes good use of several ray-trace diagrams taken from my website.
* [The discussion is mostly in terms of Lambert's model, which is
* appropriate for beginners; but its unreality tends to mislead them, as
* mirages are due to changes in lapse rate.]
* Published online: 21 February 2023 at: https://doi.org/10.5802/crphys.114
* DOI: doi : 10.5802/crphys.114
* Part of the special issue: Astronomy, Atmospheres and Refraction
* Also avaliable at
* https://comptes-rendus.academie-sciences.fr/physique/item/10.5802/crphys.114.pdf
*
* Review of inf.-mir. history, Monge's error, and reactions to it.
* The origin of the word "mirage" is examined in detail.
* I should also have cited Möbius (1925), and perhaps Garbasso's second
* (1907) paper.
* Published online at: https://doi.org/10.5802/crphys.106
* on 20 Dec. 2022
* DOI: doi : 10.5802/crphys.106
* Part of the special issue: Astronomy, Atmospheres and Refraction
* Review of astronomical refraction and extinction (airmass), and their
* relation to atmospheric structure. Shows that the Standard Atmosphere
* is unsuitable; that Cassini's model is adequate, except near the horizon;
* and that the Auer-Standish recipe fails near the top of a duct.
* Largely historical.
* Published online at: https://doi.org/10.5802/crphys.125
* on 21 Feb. 2023
* DOI: doi : 10.5802/crphys.125
* Part of the special issue: Astronomy, Atmospheres and Refraction
*
* ELLISON HAWKS's book
* ". . . you must watch carefully, for, as the minutes go by, the sun
* will get lower and lower until there is only a tiny tip left. Then,
* just before it finally disappears, you will perhaps see a little green
* flame shoot up, and the tip of the sun itself will turn green. I do not
* say that you will always be able to see this Flash, but only on certain
* occasions. I have known people only see it once out of a dozen times,
* but it is very interesting to watch the sun disappear over the horizon,
* and to look for the green Flash." (p. 60)
* So far, so good. But then, the sun ". . . will also seem a great deal
* larger than it does when seen high in the sky. This is because of the
* extra thickness of atmosphere near the horizon, which acts as a sort of
* magnifying glass and enlarges the sun, when it is low down. The moon may
* also be seen enlarged in the same way, as it rises in the east, when it is
* full." Ouch! (Well, you can't win them all.)
*
* Thanks to Charles Campbell, of Cranleigh, Surrey (UK) for the reference!
* He says it was published in 1912, but the copy I borrowed from Case,
* while undated, has "October 1910" at the end of the preface; and the
* last page of the index has a footer naming the printer (Ballantyne,
* Hanson & Co.) and the notation "5/11"; so I believe it was printed in
* 1911. This is the ninth volume in the "Shown to the Children" series.
* According to the L.C. catalog, Hawks wrote other books in that series.
* The British Library catalog credits 120 popular books to him, and dates
* this one 1910.
* Case's copy showed up with the frayed black register bookmark ribbon
* lying between pages 60 and 61 -- right at the GF entry!
* Note the GF observation by Hawks in 1909, shortly before this was written.
* TURPAIN's book on light, illustrated with photos by Rudaux
* A nice chapter on atmospheric optics, including twilight phenomena,
* zodiacal light, aurorae as well as the usual halos, rainbows, and
* mirages. Mirages and distorted sunsets are illustrated with photos from
* Rudaux; GF is illustrated with his drawings of the 1904 flash.
* Libert's "green Sun" observations are also mentioned.
* Thanks to Luc Dettwiller for a copy of this!
* CHARLES FITZHUGH TALMAN's books
* Talman is listed on the title page as "Chairman Committee on Public
* Information, American Meteorological Society"
* Crepuscular rays are treated on p. 169, ending with mountain shadows.
* Pp. 170-171 describe textbook green flashes, and red flashes. He
* seems to give a little credence to the "after image" explanation.
* Pp. 171-174 treat mirages, described as "some of the most bizarre of
* optical illusions." General Maude is mentioned on p. 173, as is
* Scoresby, and "Crocker Land".
* TALMAN's later book
* In "The Author's Apology", Talman says he "has enjoyed for a number
* of years the exceptional privilege of being the custodian of a nearly
* exhaustive collection of literature on the subject . . . ." [The obit
* on NOAA's Web pages, taken from Weather Bureau Topics and Personnel,
* July 1936, says he had been in charge of the Weather Bureau Library at
* the Central Office since 1908.]
* Facing p. 21 is a picture of "the most famous cloud in the world":
* the "tablecloth" on Table Mountain, near Cape Town.
* The treatment of mirage (pp. 114-118) is much fuller and better
* here than in the 1925 book. Looming and "lateral mirage" are briefly
* mentioned. He suggests the Flying Dutchman probably arose from
* mirages at sea. On p. 116 appears a garbled account of the New Haven
* ghost ship, here transferred to New York, and mistaken for a mirage of
* a real ship. Wilkes Land and Crocker Land are mentioned; Hubbard's book
* is named, and quoted, but without a page reference (p. 117).
* Pp. 136-137 mention sunset distortions; GF on 137-138. The Lick
* sunset photographs are mentioned (p. 137). There is now no mention of
* after images.
*
* The author says these are edited articles from Nature Magazine, Popular
* Mechanics, NY Times, etc.
* No copyright date is given for the book, only for its sources;
* L.C. says "c1931".
* W.E.Harper's Canadian radio talks -- not a book, but belongs here anyway
* This is the lead article in the Feb. 1933 issue, beginning on p.49.
* Available from ADS.
* BOTLEY -- a popularization of meteorology
* The Manx GF legends mentioned on pp. 152 and 206 are both taken from
* the same letter to The Times (M.Douglas, 1929). Botley exaggerates:
* Manx folklore does not "contain much" about it; it was barely known in
* 1929, and nobody there seems to have heard of it today. The reference
* to Rex Clements's story is also overblown. And the purported "superior
* mirage" in Plate XI (facing p.210) is almost certainly a fake.
* Yet the Italian translation of this book is O'Connell's ref. #10.
* Dr. Charles D. Neal's book for juveniles
* "When there is, near the earth, a layer of air that is warmer and
* denser [sic!] than the air above it . . . ."
* [Well, it isn't the *air* that's denser here . . . .]
* Franklyn M. Branley's treatment for juveniles
* ". . . the green flash, a bright green strip of light that appears just
* above the setting sun. Usually it is seen close to the horizon an
* instant after the sun itself has disappeared . . . . Because of its longer
* wavelength red is bent the least." (The diagram is equally poor.)
* Branley wrote many books on astronomy for children; he died in 2002.
* Compendium of reports, as in Mulder's book: this put me on to
* Starr's (1930) paper, so Corliss is accomplishing his aim here.
* Like Mulder, he quotes items and adds short comments:
* "The green flash and the crepuscular rays . . . have long been considered
* as fully explained. The stock explanations, however, seem simplistic
* when the full ranges of these phenomena are considered."
* Of "the appearance . . . of multiple green rays of light ascending from
* the point of the sun's disappearance", he astutely says, "This phenomenon
* may be related to the crepuscular rays."
* Corliss's list of 42 references contains no errors, which speaks well
* for the care he has exercised -- especially considering that the
* ``standard'' references typically have 10% to 20% errors!
* Corliss's book reviewed in JBAA
* GF is mentioned. Available from ADS.
* A juvenile book illustrated in b/w, with the usual mistakes
* Mirages are treated on pp. 14-22. Looming is treated as a mirage:
* "Looming mirages are the only mirages that appear to be nearby. They
* may also greatly magnify the real object."
* "Our first glimpse of the Sun at sunrise is a mirage."
* An interesting variation is the suggestion to observe variations in dip.
* Another juvenile book, full of strange stuff
* ". . . at sea . . . the air layer closest to the water is usually colder
* than the air layer above it. As a result, sea mirages . . . are right
* side up and above the object . . . ." (even worse about Fata Morgana)
* Acknowledgment thanks "William A. Selby, Professor of Geography/Earth
* Sciences, Santa Monica City College . . . for his critical reading of the
* manuscript."
* much misinformation, but some great photographs
* The second edition, published in 2001, is greatly improved, and RECOMMENDED.
* [Although they propagate the "fata bromosa" error.]
* This is a beautiful book, similar to the Lynch/Livingston book;
* it contains the best mirage photos I have seen. The GF pictures are
* poor, but the advice on how to obtain them is good. Unfortunately,
* the multiple inferior mirage (due to uneven ground) on p.60 is
* mis-identified as a Fata Morgana; and the price is a bit high (FF 240).
* See pp. 49-56 for the GF, and 56-60 for mirages.
* Clear presentation of the textbook story, with one of Pekka's GFs.
* Note that the wrong colors were printed on Abb.1.6 on p.24.
* Thanks to Dr. Kristian Schlegel for a copy of his book! It turns out
* to contain many fine pictures of natural phenomena, including one of
* ball lightning. The author tells me a revised edition is in the works.
* All sorts of pretty pictures, not just atmospheric optics
* Pekka's multiple-mock-mirage flash sequence is on pp. 131-133, with
* the final stage on a double-page spread. "The conditions for seeing
* the green flash, or green ray, with an unaided human eye occur only a
* few times out of every ten sunsets over a distant unobstructed horizon."
* a journalist's attempt to cover science?
* Paul Simons's book is full of errors, but has some decent coverage --
* it seems to fall somewhere between Corliss and the National Enquirer .
* The author has believed everything he's read, and has sorted out the
* most sensational accounts. So he asserts, in the introduction, that
* "The Föhn wind in Germany sends people mad," and other nonsense.
* Speculation is presented as fact; there is no index; and the "Select
* Bibliography" at the end is already secondary and tertiary sources, some
* not too reliable themselves. The book is clearly pitched at an English
* readership (British spellings throughout).
* The photographs (some by Pekka Parviainen, some by Alistair Fraser;
* some strangely reproduced with moiré stripes through them) are mixed
* with engravings from Flammarion (!)
* One of Pekka's pile-of-plates clouds is captioned ". . . lenticular
* clouds created on waves of turbulent air." And the adjacent text says
* ". . . called rotor clouds or lenticular clouds." [p. 60]
* The story of Ross mentions his "Croker Mountains" on p. 58.
* "Green Flash" is on pp.85-86: ". . . it sometimes hurls a shaft of vivid
* green light across the sky . . . ." The usual "prism" is invoked.
* While there are hints of interesting reports to pursue, the lack of
* detailed references makes most of them useless. The unwary should
* steer well clear of this confused and unreliable book.
* John Naylor's mixed bag: great photographs, some good (and some misleading)
* diagrams, some good (and some wrong) information. Many of the topics
* of interest here are covered: refraction & mirages (Ch.3, pp. 50-63);
* flattened sunsets (pp. 64-67); crepuscular rays (pp. 77-79); distorted
* sunsets (pp. 80-84); Green Flashes (pp. 84-86). All non-mathematical.
* Pekka's pictures are great. But there are some howlers: Naylor claims
* Monge made up the word "mirage" (p. 51), though he gives the correct
* etymology. He thinks mirages are due to temperature gradient, not the
* curvature of the temperature profile (p. 55). "If your eye is too high,
* it will not intercept the rays that produce the inverted image, and you
* will not see a mirage." (p. 57) [Pekka's over-sized Omega is on p. 56.]
* Ch. 4 (pp. 64-87) deals with low-Sun and twilight phenomena; GFs are
* on pp. 84-86; ". . . blue flashes have been seen . . . only from altitudes
* of several kilometres." The pictured mock-mirage flash (Fig. 4.15,
* p. 85) is mis-identified as "Green segment." Many minor errors.
* There are a number of wrong-word errors that show the manuscript was
* spell-checked but not carefully proof-read.
* The selection of references is also haphazard, including minor works
* while omitting more important ones. He has the date wrong (as 1968!)
* for O'Connell's book.
* MICHAEL VOLLMER's new book on atmospheric optics for beginners
* SUPERB photographs in the color-plates section. This is a more
* technical book than most of the ones in this section -- it's almost a
* textbook rather than a popular work. (He's not afraid to use calculus
* occasionally.) Section 11.2 (pp. 315-322) covers green flashes; there
* are also good sections on refraction in general, and mirages. Each
* chapter has a good list of references.
* Springer issued a slightly revised second edition in paperback (2019).
* MICHAEL MAUNDER's book
* GF treatments are on pp. 72-74 for morning, and 115-118 (evening).
* But he starts off with "The scientific basis for the green flash had
* to wait until 1960 [sic] when D.K.J. [sic] O'Connell of the Vatican
* Observatory produced the first [sic] authenticated color photographs
* of the phenomenon, but he [sic] took those at sunset . . . ."
* Well, it isn't all that bad, but it isn't good. "The green flash
* occurs when light is refracted through an atmospheric layer and thereby
* seems to come from this higher layer." (All this from the top third
* of the first page! He does manage to connect flashes with mirages,
* but clearly doesn't understand either one.)
* On p. 74, we get: "Blues should never be possible and it is difficult
* to give an explanation." [Especially if you don't understand GFs.]
* The mirage discussions on pp. 101 ff. aren't much better; he confuses
* inferior mirages with looming and normal refraction: "The interface
* acts very much as a mirror with light reflected back from the much
* denser air above. . . . this mirage is described as an 'Inferior' mirage,
* from the reflection back from above." (p. 101)
* Like O'Connell, he takes the gaps between multiple mock mirages as
* "blind strips": "These multiple mirages often lead to a whole series of
* green flashes, often seen underneath as well as above, as each layer pass
* through the boundary layers in the atmosphere." (p. 103, strictly sic .)
* Pretty awful. Too bad Patrick Moore's name is on this series.
* MARCELLO SÉSTITO's peculiar "Fata Morgana" book
* A beautifully produced "coffee-table" book, which plays with the
* idea of reflections in its design and illustrations. The author is an
* architect who seems enchanted with the idea of mirror images and symmetry,
* and the architectural theme in the historical accounts of these mirages.
* The first 31 pages provide a brief sketch of the myth of Morgana and
* the literature of the mirages, followed by two pages of more detailed
* references to some sources of information. I was glad to see Boccara's
* paper cited; but Costanzo's is not. And the author has unfortunately
* ignored Boccara's advice about the unreliability of many old works.
* Then come several sections: "Quaderni" ["Exercises"], of colored
* sketches and art studies inspired by the stories connected with Morgana;
* and then other, more formal paintings devoted to Morgana herself, the
* Strait, and Kircher's "Catoptic Theater". Many of these echo motifs
* seen in Fortuyn's engraving, which is well reproduced on p. 128, just
* before the beginning of the second half of the book.
* This second half is a series of Appendices that reproduce several
* well-known works devoted to the mirages, beginning with Minasi's classic
* Dissertation of 1773. Unfortunately, it is followed by some of the most
* unreliable essays ever published on this subject: those of Capozzo
* (1840), Saffiotti (1837), Giardina (1758), etc. Minasi's text and
* Capozzo's are printed in two-column format, with a vertical rule that
* separates the columns; but Saffiotti's and Giardina's are reproduced
* in a peculiar 4-up format that retains the 2-column arrangement, so that
* each photocopied page image at bottom of a book page follows the image
* immediately above it; the reader must envision an invisible 2-column
* format, instead of reading pairs of page images side by side.
* Fortunately, the page images bear the original page numbers. As in
* Consolo (1993), Minasi's notes are re-numbered by section instead of
* by pages, and some copying errors in Consolo's version, including his
* errors in re-numbering Minasi's footnotes, are exactly reproduced
* here; so it seems that this is a third-hand copy of Minasi.
* Minasi's text and Capozzo's are separated by a double-page spread
* that reproduces a widely-reprinted wood engraving from 1865 that falsely
* depicts some imaginary superior mirages, with the upper images shown
* impossibly enlarged in azimuth as well as unrealistically elevated
* in altitude. The misleading text of Giardina, with Gallo's notes and
* Allegranza's garbled commentary, are followed by another pair of phony
* "mirage" images from the 19th Century, including the frequently reproduced
* fantastic image "Mirage in the Desert" from Hartwig's 1875 "The Aerial
* World"; here, Hartwig is mis-identified as "Hartwing". Caveat lector!
* However, the photocopied texts are followed by the little-known but
* influential discussions led by Johann Reinecke in the pages of Allgemeine
* Geographische Ephemeriden in 1800, which have been capably translated
* from German to Italian by Mario Izzi. The copperplate engravings
* (Tafeln I & II) from Reinecke's initial discussion, which are hard to
* obtain, are usefully reproduced on (unnumbered) pages 206 and 208.
* Incredibly, this Italian translation of Reinecke's comments actually
* includes an Italian translation of Reinecke's German translation of
* Nicholson's English translation of Minasi's original Italian description,
* even though this book has already reprinted Minasi's original Italian
* text a few dozen pages earlier. So we get to read the third-generation
* version: "Quando il Sole al mattino raggiunge un'altezza tale che i suoi
* raggi formano col mare di Reggio un angolo di incidenza di circa 45
* gradi, . . . " instead of the original "Quando il nascente Sole splende
* in punto, onde l'incidente suo raggio formar possa sul mare di Reggio
* l'angolo di gradi 45 circa, . . . ". Well, maybe it's useful to show the
* modern Italian reader what the 19th-Century German reader read about
* what the 18th-Century Italian writer really wrote; but maybe not.
* Then come more than four pages of annotated bibliography, containing
* many other little-known and obscure references on Fata Morganas. They
* contain some valuable citations to the recondite literature; but they
* also contain many obvious errors. For example, Humphreys' middle
* initial is given as "L" rather than "J", and the title of his textbook is
* printed as "Phisics" of the Air instead of "Physics"; furthermore, only
* its 1929 edition is mentioned, although the 1940 revision contains
* additional information about mirages. Only the abridged 1671 edition
* of Kircher's Ars Magna (the one with the typo that fooled Marina
* Warner) is cited for Angelucci's letter, rather than the more correct
* text of the original 1646 edition; and the heading of the section is
* cited with "sine" in place of "siue". Similarly, only Pernter's 1902
* edition of Meteorologische Optik is cited, rather than the expanded
* 1910 revision by Exner, let alone the 1922 second revision. Another
* example of carelessness is the misspelling of Marina Warner's last name
* as "Worner", which caused her unreliable book "Phantasmagoria" to be
* placed after Elizabeth Werner's 1896 work. This shows the error to be
* the author's, not that of the printer or proofreader.
* Strangely, the references cited in the bibliography section do not
* include several other useful references that appear in the Notes on
* pp. 32-33, such as Boccara's fine review of the literature before 1900;
* so it is necessary to consult the Notes as well as the Bibliography
* to discover all of Séstito's sources. His omission of important works
* like Costanzo's review and the later editions of both Humphreys and
* Pernter & Exner reveal his unfamiliarity with the mirage literature.
* As is usual with the Fata Morgana literature, one needs considerable
* experience with the field to separate the wheat from the chaff; this
* book contains an abundance of both.
* I was pleased to see the woodcut, or wood engraving, on the
* penultimate page of the book, which illustrates the classical
* demonstration of refraction described by Euclid and Cleomedes.
* It would be nice to know what 19th-Century textbook was its source.
* Special thanks to Marcella Giulia Pace for bringing this attractive
* and useful work to my attention, and for providing a copy!
*
* original edition of Part I of Minnaert's book;
* note that there are three parts to this monograph.
* They are now available on the Web at:
*
* http://www.dbnl.org/tekst/minn004natu01_01/minn004natu01_01.pdf
*
* He introduces verdwijnlijn and grenslijn on p. 47.
* The "Groene Straal" is introduced with a quote from Verne, and a
* reference to Mulder's book; then comes "Volgens een oude Schotse
* legende . . . ." (p. 58)
* first English translation of Part I:
* The term "vanishing line" appears for the first time here, on p. 48
* REVIEW of the 1940 edition; mentions "the green ray".
* I suppose the reviewer is Thackeray.
* REVIEW of the 1940 edition; mentions "the green ray"; and calls
* Hillers's mural-mirage photo "one of the oddest" in the book.
* This should be the same as the 1940 edition
* "According to an old Scotch legend, . . . "
* He has "Continho" for Coutinho
* Note that he endorses Forel's explanation for the Fata Morgana (p.53)
* The Dover edition brought Minnaert's work to a much wider public.
* Even so, his term "vanishing line" does not appear in the technical
* literature until 1960.
* O'C #91
* new translation of Minnaert
* and refraction terminology
*
* NOTE: This file is mainly the "mirage" articles from a number of
* encyclopedias, dictionaries, and similar reference works.
*
* "MIRAGE; an optical phenomenon, produced by refraction. The unusual
* elevation or apparent approximation of coasts, mountains, ships, and other
* objects, has long been known under the name of looming ; and, if the same
* phenomenon is accompanied by inverted images, it is called a mirage ."
* N.B.: "A popular dictionary of arts, sciences, literature, history,
* politics and biography, . . . on the basis of the seventh edition of the
* German Conversations-Lexicon." [see below for a later edition of that]
* "Under it are classed the appearance of distant objects as double,
* or as if suspended in the air, erect or inverted, etc."
* But there are some errors: "In particular states of the atmosphere,
* reflection of a portion only of the rays takes place at the surface of
* the dense medium, and thus double images are formed, one by reflection,
* and the other by refraction -- the first inverted, and the second erect."
* And: "The Spectre of the Brocken , in Hanover, is another celebrated
* instance of mirage."
* "Mirage is the appearance in the air of an erect or inverted image of
* some distant object which is itself invisible." (Garbage.)
* "Luftspiegelung . . . bewirkt, daß Gegenstände, die sich u n t e r
* dem Horizont befinden, deutlich sichtbar, also gewissermaßen gehoben
* werden . . . , oder daß ü b e r dem Horizont befindliche Gegenstände
* doppelt, vergrößert oder umgekehrt in der Luft schwebend erscheinen."
* There is a fine laundry list of TERMINOLOGY here: "Die deutschen
* Seeleute nennen diese Erscheinung K i m m u n g , die englischen
* L o o m i n g , die holländischen U p p d r a c h t , die
* französischen M i r a g e . In Indien nennt man die L.
* C h i l t r a m , » Bild « , oder S i k o t a , » Schlösser der
* kalten Zeit « ; bei den Arabern heißt sie S e h r a b ,
* » geheimnisvolles Wasser « , auch Bacher el Alfrid, » Sohn des
* Teufels « , oder Bacher el Gazal."
* Albright's treatment of the green flash is straightforward and accurate.
* But his section 6 on "Mirages" in Chapter XX leaves much to be desired:
* "The mirage is an optical illusion due to the refraction of light as
* it passes through nonhomogeneous layers of the atmosphere. Distant
* objects are seen in an unnatural position, sometimes elevated, sometimes
* depressed, and often inverted." (p. 355)
* He also seems to think that any images in excess of 2 must be due to
* reflection on water; in discussing the superior mirage, he says (p.357):
* "If the mirage occurs at sea, the image of a distant ship and of its
* reflection in the water also may appear in the sky, the image of the ship
* inverted and the image of the reflection erect, as shown in Fig. 231."
* [N.B.: This spurious suggestion was already made in 1806 by Kries.]
* His description of looming confuses it with ordinary terrestrial
* refraction; his illustration on p. 358 shows a flat Earth!
* Thiessen's Glossary cites Albright's text (above), but omits its
* worst errors. Here looming is succinctly described as "An optical
* phenomenon in which objects below and beyond the horizon appear to
* the view of the observer, and even the horizon itself is extended."
* (I think he is saved by also referring to Humphreys.) Unfortunately,
* for "mirage", he simply quotes the first passage from Albright (see
* above). Here again, he cites Humphreys as well. (p. 188)
* Note that this is "W. B. No. 1445 Issued August 1, 1946" and "Reprinted
* May 1949".
* Hans Neuberger (Penn. State) cites 59 references.
* He gives the standard textbook explanation of the green flash, but adds:
* ". . . most observations seem to be associated with refractions in excess
* of the normal," citing Meyer (1939) and Visser & Verstelle (1934).
* He correctly describes looming, sinking, towering and stooping, and
* attributes the mathematical theory of these to Exner (in P&E II).
* His description of mirages as "one or more images of the object"
* clearly means extra images; he seems to fall into the error of
* assuming that one image is "the object" itself.
* A definition that tries to be all things; or at least to cover all
* mirages -- to its detriment:
* "MIRAGE: An optical phenomenon consisting mainly of steady or wavering,
* single or multiple, upright or inverted, vertically enlarged or reduced,
* images of distant objects."
* About all that is useful here is "distant objects"; though "mainly"
* is a nice touch, in light of the rest of the arm-waving! Furthermore:
* "Objects seen in a mirage sometimes appear appreciably higher or lower
* above the horizon than they really are; the difference may amount to as
* much as 10 degrees." So this is all nonsense.
* In addition, they use the curious non-standard terms "lower mirage"
* and "upper mirage" (in place of "inferior" and "superior", respectively.)
* Another completely wrong-headed attempt:
* "mirage -- A refraction phenomenon wherein an image of some object is
* made to appear displaced from its true position."
* On the other hand, looming, towering, etc. are described correctly
* on p. 349, though described as a "mirage effect".
* The WMO is still confused:
* "Mirage: Optical phenomenon consisting essentially of steady or
* wavering, single or multiple, upright or inverted, vertically enlarged
* or reduced, images of distant objects." (p. 117) [Note that "mainly"
* has now become "essentially"; otherwise, their folly goes on unchanged.]
* Worse yet, they now think there is a distinction between an "image"
* and "the actual object":
* "Superior mirage: Special case of mirage , . . . in which the virtual
* image is above the actual object." And:
* "Inferior mirage: Particular case of mirage , . . . in which the virtual
* image is found below the actual object." (both on p. 118)
* (Note that what they call a "virtual image" is in fact a real image, not
* a virtual one.)
* Fairbridge has the same problem:
* "MIRAGE, FATA MORGANA: The mirage is a general category of atmospheric
* optical phenomena involving refraction of light rays bent by differential
* heating of a land or water surface, which results in the distortion or
* displacement of some object viewed, sometimes leading to a misleading
* optical illusion. . . .
* "Three major types of mirage are recognized:
* "The inferior mirage , where the false image is seen below the true
* position of the object viewed."
* Note that the diagram on p. 606 is reproduced from Hutchinson's book
* on limnology. Fairbridge cites all the right references, but seems to
* have misunderstood them. This article is signed by Fairbridge himself.
* . . . and so does McIntosh:
* "Two main classes of mirage occur, (i) `inferior' and (ii) `superior',
* in which the virtual image is below and above the object, respectively."
* (Of course all this nonsense about "virtual images" is quite wrong:
* it is the erect images that are virtual and the inverted ones that
* are real!) Worse yet, after discussing the superior mirage:
* "In such physical conditions multiple reflections may give rise to
* various images, some displaced laterally with respect to the object,
* as in FATA MORGANA."
* Fortunately, the Second Edition is far better -- both more complete
* and more accurate -- than the First. Green flashes are connected with
* mirages; mirages are explicitly stated to be all images, not an "object"
* plus (supposedly spurious) "images". "Lateral mirages" in the
* wrong-headed sense are refuted: "the rare reports of such sightings
* undoubtedly arose from misinterpretations of observations." The lifted
* inversions responsible for superior mirages "are common over, but hardly
* confined to, enclosed bodies of water on warm afternoons when the warmer
* air from the surrounding land flows over the colder water." And the
* initial definition of "mirage" as "An image formed when the atmosphere
* behaves as a lens" is succinct and accurate.
* On the other hand, there are still a few points I'd quibble with.
* Looming and sinking, stooping and towering are all called "mirages".
* Multiple images are attributed to periodic thermal inhomogeneities.
* Inferior and superior mirages are distinguished according to the
* direction of "displacement" of the image. And the Fata Brumosa is
* mistakenly called "Fata Bromosa". Alas, no references are cited.
* Still, this must be regarded as about the best modern summary of
* refraction phenomena available.
*
* Pernter's original 1902 edition, before Exner got involved
* This edition treats only mirages; there is no mention of green flashes.
* It contains only 212 pages, and does not reach halos and rainbows.
* However, there is much material on the Moon Illusion and its possible
* explanations (pp. 42 ff.) that was removed by Exner in later editions;
* notably the references to Ptolemy's "Optics", and the reference (note 1
* on p.42) to Ptolemy's belief in the Almagest that the "vapors at the
* horizon" are involved.
* Dr. Svante August Arrhenius may have the first textbook account
* The "textbook" story appears here: "Da die roten Strahlen die geringste
* Brechung erleiden, verschwindet zuerst das rote Bild der Sonne unter dem
* Horizont, zuletzt das blaue."
* There is also good coverage of mirages, including a reference to Budde
* (but no citation) on pp.832-835.
* Refraction begins on p.827; dispersion appears on p. 829.
* As the organization and title of the chapter on "Meteorologische Optik"
* are exactly the same as in Pernter's book, that was evidently the model
* for this.
* (Cited by Mulder)
* Here Exner adds a great deal of material, including GF on pp.798-799
* at the very end of the volume. He accepts Julius's 1/10 second and so
* must reject Henry's 1 sec., but can't swallow the anomalous dispersion;
* so "Einfacher scheint es, . . . die selective Absorption des Wasserdampfes
* zu berücksichtigen." Though there is no mention of either Abbe or
* Tyndall, I suspect this notion came from Abbe's 1905 editorial in MWR.
* Thanks to Günter Können for a copy of this!
* Sir John William Moore's curious book on meteorology
* The author was a professional physician, and an amateur meteorologist.
* His book is full of speculations about the effects of the weather and
* climate on disease. This 2nd edition contains a two-page Appendix on
* green flashes (listed in the Contents as "The Green Flash at Sunrise
* and Sunset", and on p. 459 both as just "GREEN FLASH" (below the word
* "Appendix") and "The Green Flash on the Horizon at Sunset" (in italics).
* It contains a brief review of the subject, concentrating on the 1906
* discussions in Symons's Met. Mag., and especially on Rambaut's refutation
* of Lippincott. No further mention of refraction phenomena.
* A very brief exposition of the textbook model
* Börnstein mentions only Julius's anomalous-dispersion explanation
* -- which I hardly think qualifies as "Gemeinverständlich"!
* (Full title is "Leitfaden der Wetterkunde -- gemeinverständlich
* bearbeitet von Dr. R. Börnstein, Geh.Regierungsrat" etc.)
* Dritte umgearbeitete und vermehrte Auflage
* ". . . der `grüne Strahl' . . . nennt man das ganz kurz dauernde
* Aufleuchten eines smaragdgrünen Flämmchens an derjenigen Stelle des
* Horizontes, wo die untergehende Sonne gerade verschwunden ist. . . ."
* Thanks to Steve Williams for getting this. (cited by Mulder)
* Author at least reports a couple of GFs he saw himself, as well as both
* inferior and superior mirages (p.82). Good clear presentation of the
* standard model at an elementary level, with clear diagrams.
* A standard textbook account, often cited
* Wegener's mirage theory is reproduced on pp. 151-155.
* Unfortunately, the French literature is shortchanged here: though
* Biot's mirage monograph is cited, and we have a few mentions of standard
* reference works like Mascart's "Traité", Bouguer and Bravais are cited
* only in connection with Halos, and astronomical refraction is mentioned
* mostly in vague gestures toward "astronomical textbooks."
* Green flashes are mentioned only in the last 3 pages (901-903). The
* colored plate at the end of the book shows Wegener's Nachspiegelung.
* Available at the HathiTrust.
* O'C #101
* Alphonse Berget's interesting book, illustrated by Lucien Rudaux
* Chapt. 3 (pp. 20-27) covers refraction phenomena, and contains many of
* Rudaux's monochrome photographs of low-sun phenomena. Fig. 14 on
* p. 24 is noteworthy. P. 25 shows a mirage photograph and drawings.
* There is a nice COLOR PLATE facing p. 24 that shows some of Rudaux's
* drawings of sunsets and green flashes.
* Thanks to Eric Frappa for pointing this out!
* R.W.WOOD
* "It has frequently been contended that the phenomenon is an illusion due
* to contrast, the green spot being an `after-image.' This however is sheer
* nonsense, as any trained observer can testify."
* BUT: ". . . the case of mirage . . . would be unfavorable for the occurrence
* of the green flash" (assuming super-refraction is the cause).
* N.B.: Reprinted by Dover, 1967.
* HUMPHREYS's book
* Pp. 466-467 give the "textbook" GF description; no numbers or diagrams.
* The section on atmospheric optics is a slightly updated version of
* his 1919 J. Franklin Inst. paper; the 2nd ed. (1920), on Google Books,
* says "Pub. for the Franklin Institute . . . by J.B. Lippincott Company".
* The Fata Morgana section is the last 2 pages (pp. 474-475) of the
* mirage discussion. In the 3rd ed., he adds a reference to Schiele's
* thesis, calling it "an elaborate mathematical treatment of" the F.M.,
* and including the Japanese (Geophys. J.) refs. from Schiele.
* Although this is a standard textbook, I have found that some people
* with no background in physics or optics have difficulty in following it.
* In particular, the brief description of "looming" is too terse -- and
* confusing, because of his mentioning the older broad use of that term
* for all sorts of refraction effects at the horizon.
* probably O'C #54 is a garbled version of this book.
* Standard textbook story
* [Newton Lacy Pierce has a prize named after him, awarded by the AAS.]
* BOWDITCH
* Apparently Bowditch acquired the GF paragraph 3821 in 1958;
* the 1943 edition of H.O. 9 lacks it, but it's there in the 1958 one.
* The Decennial Indices to U.S.Govt. pubs. list no edition between.
* Gives the standard Rambaut-Rayleigh story, but with a nice simile:
* "The effect is similar to that of imperfect color printing in which the
* various colors are slightly out of register."
* ". . . the greatest difference, which occurs between violet at one end of
* the spectrum and red at the other, is about ten seconds of arc."
* ". . . under suitable conditions is far more common than generally
* supposed. . . . With a sharp sea horizon and clear atmosphere, an
* attentive observer may see the green flash at as many as 50 percent of
* sunsets and sunrises, although a telescope may be needed for some of
* the observations."
* "Usually it lasts for a period of about half a second to two and
* one-half seconds with about one and a quarter seconds being average."
* ??? WHERE DID THESE NUMBERS COME FROM ???
* This same treatment occurs on p. 500 of the 1995 edition, available
* on-line at
*
* http://www.irbs.com/bowditch/
*
* Full title is:
* The American Practical Navigator, an Epitome of Navigation
* originally by Nathaniel Bowditch, LL.D. [honorary degree from Harvard]
* published by the U.S.Navy Hydrographic Office . . . .
* S.W.VISSER
* Gives the std. textbook story, but then admits it isn't adequate, and
* that "irregular refraction" is certainly necessary for a good display.
* Fairly good short account; cites only O'Connell
* BUT: "It occurs when refraction in the atmosphere close to the Earth's
* surface is abnormally great . . . ."
* Good "Handbuch" treatment of optical subjects
* "Grüner Strahl", pp.352-353, cites only Meyer's article in Hb.d.Geophys.
* and shows a sketch of Lagaaij's green ray (without attribution). The
* explanation of the phenomenon is a bit muddled, but mostly follows the
* textbook story; however, following Meyer's lead, "Treten nun infolge
* außergewöhnlicher Temperaturschichtung -- insbesondere wahrscheinlich
* durch das Vorhandensein tiefliegenden kräftigen Inversion -- zusätzlich
* Luftspiegelungen und damit in Verbindung wohl auch anormale Verhältnisse
* der atmosphärischen Dispersion in diesen Schichten auf, dann können
* Zerrbilde des oberen Sonnenteiles als Erklärung für den grünen Strahl
* angenommen werden. Es wird auch vermutet, daß die Absorptionsbanden des
* Ozons und des Wasserdampfes im sichtbaren Spektralbereich hierbei mit eine
* Rolle spielen. Eine befriedigende Theorie für den ganzen
* Erscheinungskomplex des grünen Strahls gibt es jedoch noch nicht."
* So this is one of the BEST and MOST TRUTHFUL accounts to be found!
* The "Luftspiegelung" article (pp.498-500) also cites P&E, and redraws
* several of Wegener's diagrams. Both articles are credited to Foitzik.
* Thanks to Siebren van der Werf for this reference!
* Maybe this is the source of Fraser's and McIntosh's error:
* "It is related to the greater Rayleigh scattering and refraction in the
* short wavelengths (violet, blue, green) than in the long (red) waves of
* sunlight. Under hazy conditions it may appear blue or violet."
* (sure sounds as if one copied from the other.)
* (Fairbridge buries "Green Flash" under "Twilight")
* Standard textbook story, well presented
* a JUVENILE book
* Unaccountably quotes from Mostyn's 1891 Nature paper, but confuses
* him with Nijland's similar obsn. & says they were together!
* All the photos are in b/w, alas. Ch.2 is "Green and Blue Flashes".
* SUNSET PHOTOS and refraction in final chapter
* Ch.7 and Plates 7-10 and 7-11 show distorted sunsets
* p.177: "All are variations of the same effect and all, in my judgment,
* may appropriately be given the same name." (green flash)
* He even has a section called "The green flash legend" (pp.172-173), and
* quotes from Verne!
* Note his good (though brief) treatment of the Fata Morgana on pp.
* 165-167 and Plates 7-4 to 7-7.
* Alan H. Batten reviews Greenler's book, citing Hogg's JRASC mirage paper
* No mention of GF. Available from ADS.
* MEINELS' BOOK
* probably the best GF treatment available in hard covers, though the
* references are spotty
* Replete with errors from Botley, etc.;
* but they recognize that ADAPTATION plays a part.
* Kurt Nassau's "Fifteen Causes of Color" book
* A good explanation of the "textbook" flash, with "prism" analogy.
* Thanks to Dave Fenner for pointing this out!
* DUTTON
* The same passage appears on p.620 of the 12th edition, edited by
* G.D.Dunlap and H.H.Shufeldt (1969 - 1972), except that Maloney has
* changed "The" to "A" at the start of the final sentence.
* ". . . the longer waves of red being least refracted, the shorter blue
* and violet waves being more refracted. The red, orange and yellow light
* is cut off by the horizon when the blue and violet is still momentarily
* visible. These blue and violet rays cause the green flash." [SIC!]
* [This nonsense seems to have appeared in the 12th edition, in 1969.]
* [It is not in the 4th (1961) printing of the 1957/58 edition.]
* "It is estimated that at sea in the tropics, the green flash may be seen
* as often as 50 percent of the time; it is, of course, easier to observe at
* sunset. The green flash usually lasts for a period of between one-half
* and one second." Again -- cf. Bowditch! -- mysterious numbers.
* This can't be what Cotter (1968) was objecting to:
* "Using the time of the green flash to obtain a line of position is
* merely a variation of the horizon sight described in the previous article.
* It is somewhat easier to determine the time of the flash than to determine
* the instant the sun's upper limb disappears below the horizon, when there
* is no green flash." [because this appeared after Cotter's book]
* 1972 edition of the glossary originally published in 1916 by the Met.Office
* Looks as if the GF entry was not updated since Mulder's book:
* ". . . greater degree of RAYLEIGH SCATTERING experienced by the violet and
* blue rays. In a hazy atmosphere such differential scattering may not be
* appreciable and the flash may then appear blue or violet."
* This is the same error made by Fraser (1972) and it is likely he got it
* from an earlier edition of this, or from Fairbridge (above).
* ". . . the analogous very rare phenomenon of the `red flash' . . . ."
* Vincent J. Schaefer never saw a GF, I'll wager!
* "Plate 9. . . . The green flash is never seen under the conditions that
* produced the sun's image in this photograph." (Actually, it looks like a
* very good opportunity for a mock-mirage flash; the reddening is
* appreciable, but not excessive.)
* "Quite rarely . . . only occurs when the atmosphere is extremely clean . . . ."
* Caption to Fig. C.Pl.9 says "The atmosphere develops small density
* differences that create the spreading [sic] of the image."
* BLUE-SKY CONFUSION error: (quoted by Hechler, 1994)
* ". . . der noch etwas später verschwindende blaue Oberrand der Sonne
* wegen des mangelnden Farbkontrastes zur bläulichen Himmelsfarbe dem
* Auge nicht sichtbar wird."
* NOT YET IN HAND
* Craig Bohren wisely confines his attention to the Green Rim.
* But he brashly states that "there is a Scottish legend . . . ."
* (Thanks a lot, Jules Verne!)
* "It is indeed true that the green flash is rarely observed, but not
* because it is rarely observable. The sad truth is that most people are
* only dimly aware of their surroundings." You said it, Craig!
* Chet Raymo describes his fruitless search for green flashes
* The reason is not hard to find: "I have sat on the high rocky spine of
* the Dingle Peninsula and watched the sun sag into the North Atlantic."
* Much of the peninsula is over 500 m above the sea; the highest point is
* some 950m high -- all much too high for a inferior-mirage flash to be
* seen without aid; and in a region not much subject to strong inversions.
* He depends mainly on O'Connell's 1960 Scientific American article,
* which he mistakenly thinks had the first color photographs. Much of the
* wording here is identical to his 1990s columns in the Boston Globe .
* [Placed here as it is a tutorial account.]
* Review of the paperback edition of Greenler's book in JBAA
* GF is mentioned. Available from ADS.
* not exactly a textbook, but compiled by and for amateur astronomers
* This is one of the few places where one reads that ". . . it can be safely
* observed with binoculars or a telescope." The description applies to the
* inferior-mirage flash; the advice is sound.
* This popular textbook seems to be the source of the canard about the
* Byrd expedition: "Members of Admiral Byrd's expedition in the south
* polar region reported seeing the green flash for 35 minutes in September
* as the sun slowly rose above the horizon, marking the end of the long
* winter." The actual date was Oct. 16, and the observation was made at
* sunset, not sunrise -- see Owen (1929), Davies (1931) and Haines (1931).
* (Note that Little America was some 11 degrees from the Pole.)
* Also, there is a curious statement about "purple light".
* However, there is also the correct statement, "Usually, the green light
* is too faint to see with the human eye. However, under certain
* atmospheric conditions, such as when the surface air is very hot or when
* an upper-level inversion exists, the green light is magnified by the
* atmosphere."
* MARINE OBSERVER'S HANDBOOK
* The 7th Edition (June, 1950) cited by Hilder (1951) bears the cover
* title: "Manual of Meteorological Observing. Part II. Marine Observer's
* Handbook". That edition gives GF on p.74, and very little on mirage.
* Final paragraph mentions 3 forms of GREEN RAY or fog
* CRAIG BOHREN's encyclopedia article
* The GF treatment is on pp. 423-424.
* "Compared to the rainbow, the green flash is not a rare phenomenon."
* It is preceded by a section on the distortion of the setting Sun, which
* follows Fraser in forgetting about dip, so that the miraged multiple
* images are attributed to gravity waves.
* COLLIER'S ENCYCLOPEDIA
* The whole "Atmosphere" article is pp.161-172; the GF is only a
* two-sentence paragraph. The description is vague and incorrect.
* A popular book on meteorology devotes 2 full pages to "the green flash"
* (including "the Scottish saying" and the textbook explanation.)
* Mirages get the same uneven treatment, and the Novaya Zemlya effect
* is made to appear a normal concomitant of green flashes, "after the Sun
* sets". The bogus term "fata bromosa" appears on p. 51. But the authors
* have tried hard to bring meteorology to the public, despite such lapses.
* A curious feature of this book is that all of the numerous photographs
* are in black-and-white -- no color work, even in the rainbow picture.
* [The authors tell me their publisher cheaped them out here.]
* Another odd thing is the confusion over the publisher. The title page
* says "A Touchstone Book . . . Published by Simon & Schuster"; the reverse
* says "A Fireside book" but also "Touchstone and colophon are registered
* trademarks of Simon & Schuster Inc." The authors retain the copyright.
* Amazon.com says "Fireside". The authors' Web page says "Simon &
* Schuster". The review in Kirkus Reviews says "Touchstone".
* [The Svarneys say the publisher should be given as S&S.]
*
* [see also Hoppe (1941) in GF file, and Bessel (1823) in REFR. OBS. file.]
*
* DISCOVERY of RED and BLUE RIMS by Delisle
* Observing at Luxembourg, 25 Jul. 1715, Delisle says:
* "J'ai été fort attentif à examiner si Jupiter & ses Satellites ne
* prenderoient pas à l'approche de la Lune des couleurs semblables à
* celles que j'avois vû dans l'Eclipse de Venus le mois passé ; mais
* je n'en ai pu remarquer aucune qui se puisse attribuer à l'approche
* de la Lune." (He was accompanied by Chardeloup, from the Roy. Soc. in
* London; Delisle used a 20-foot telescope, and Chardeloup an 8-ft.)
* "Pour nous mieux préparer à observer ces couleurs, nous avions examiné
* avant l'Eclipse les couleurs que la Lunette causoit à Jupiter, & nous
* avons trouvé ces couleurs toûjours dirigées au centre de la Lunette,
* le rouge étant en dedans, comme cela devoit arriver. J'ai aussi aussi
* [sic] fait remarquer à M. Chardeloup que Jupiter prenoit vers l'horizon
* les mêmes couleurs, mais qu'elles provenoient d'une autre cause, car
* elles étoient dirigées autrement, le rouge paroissant toûjours le
* plus près de l'horizon, & le bleu le plus éloigné, & cela dans quelque
* situation de la Lunette que l'on place Jupiter. Ainsi les couleurs que
* nous avons remarqué dans cette Observation, provenoient ou des Lunettes
* ou de l'approche de l'horizon, & nullement de l'approche de la Lune,
* Jupiter nous ayant paru très-blanc pendant son Immersion & son Emersion."
* Thus, he was not sure whether the effect near the horizon was real or
* a telescopic artifact. (Cited by Bouguer, 1748.)
* RED and BLUE RIMS DISCOVERED on Sun by BOUGUER
* This is the ``meeting abstract'' -- evidently written by the Secretary,
* as Bouguer is referred to in the 3rd person.
* The paper is mostly about Bouguer's invention of the heliometer;
* but, in the early observations, ". . . il a toûjours trouvé les bords
* supérieur & inférieur plus ondoyans que les bords latéraux, & de
* plus, toûjours affectés de couleurs qui y forment un iris incommode;
* cette apparence peu sensible, lorsqu'on se sert de lunettes de sept à
* huit pieds, telles qu'on les a jusqu'ici employées à la recherche du
* diamètre di Soleil, devient très-marquée dans l'heliomètre; & les
* couleurs même qu'on observe dans les deux bords, lui en ont indiqué
* la cause: on sait qu'un rayon qui nous vient du Soleil n'est pas un
* rayon simple, mais un composé de sept faisceaux de rayons de couleurs
* différentes, & tous différemment refrangibles. Le plus haut point du
* diamètre vertical sera donc vû par le faisceau de rayons bleus qui
* souffrira une plus grande réfraction, & qui par conséquent le fera
* paroître plus haut, & son extrémité la plus basse par le faisceau
* de rayons qui aura souffert la moindre réfraction, c'est-à-dire le
* faisceau de rayons rouges . . . ." (p. 93)
* So Bouguer understood that the effect is due to ATMOSPHERIC DISPERSION.
* No doubt SIMULTANEOUS CONTRAST helped him detect the color difference.
* ". . . on observera toûjours le bord supérieur terminé par un trait
* bleu, & l'inférieur par un trait rouge, au lieu qu'on n'observera rien
* de pareil dans les bords latéraux, parce que la réfraction de leurs
* rayons se fait dans un plan vertical, & sans les déranger en aucune
* façon dans le sens du diamètre horizontal, dont elle ne peut par
* conséquent altérer ni la couleur, ni la netté, ni la mesure." (p. 94)
* (mentioned, but not cited, by Arago in 1836.)
* Cf. St. Chevalier (1913)!
* Actually printed in 1752.
* The details of Bouguer's HELIOMETER and COLORED RIMS on the Sun
* The first 2/3 or so of this paper are devoted to explaining why the
* horizontal diameter of the Sun could not be measured accurately:
* before equatorial telescopes with good clock drives were available,
* the image moved too fast to check the opposite limbs simultaneously
* with a filar micrometer, and the diurnal motion was too fast to allow
* accurate determinations of the east and west limbs by timings with a fixed
* telescope: "Tout la difficulté qu'on trouve dans cette observation,
* consiste à estimer les fractions de secondes . . . on se trompera
* aisément d'un tiers ou d'une moitié de seconde de temps, ce qui en
* produire jusqu'à cinq ou six, ou même sept de degré sur le diamètre."
* There is also the problem that the clock escapement is not exactly
* symmetrical, so that long and short intervals alternate (pp. 20-21).
* Furthermore, the Moon usually (because of its phase) shows only a full
* diameter in an oblique direction, and so cannot be well measured at all.
* Bouguer seems to have been inspired by the binocular: "On sait
* que le binocle avoit été imaginé pour procurer aux observateurs la
* prétendue commodité de regarder le même objet avec les deux yeux.
* Le nouvel instrument, l'héliomètre ou l'astromètre dont nous
* voulons introduire l'usage, fera voir au contraire avec un seul oeil deux
* objets à la fois, ou deux parties du même, quoique considérablement
* éloignées l'une de l'autre . . . ." [p. 23]
* He diminishes both the brightness and the chromatic aberration by
* reducing the apertures to 6 or 8 mm: ". . . on peut diminuer extrêmement
* les ouvertures des objectifs; % ce sera toûjours le mieux, lorsqu'on ne
* se proposera de mesurer que les diamètres du Soleil. Il sera avantageux
* de réduire alors par des diaphragmes, les deux verres à une simple
* partie de pouce, ou à trois ou quatre lignes de largeur; car on évitera,
* par ce rétrécissement, presque tout le mauvais effet de la séparation
* des rayons colorés qui ternissent les bords de l'astre." [p. 25]
* The state of technical optics in 1748 was dismal: "Un Artiste adroit
* a taillé dans le même bassin huit objectifs de 18 pieds de foyer; &
* c'est entre ces huit verres que j'en ai choisi deux : la précaution
* d'en faire tailler plusieurs s'est trouvée utile; deux ou trois de ces
* objectifs, soit que cela vînt de leur figure ou de ls diverse densité
* de leur matière, avoient leurs foyers différens de 7 à 8 pouces,
* quoiqu'on eût tachéde les rendre parfaitement égaux." [p. 27]
* Finally, he reports his preliminary attempts to verify the sphericity
* of the Sun: "On sait que c'est un des effets de notre atmosphère de
* diminuer un peu les diamètres verticaux apparens du Soleil & de la
* Lune; ce qui vient de ce que la réfraction élève un peu plus le bord
* inférieur de leur disque que le supérieur. Il n'y a personne qui n'ait
* vû ces deux astres sous une forme sensiblement elliptique, lorsqu'ils
* étoient très-voisins de l'horizon & sujets à des réfractions
* plus fortes. Il doit arriver encore quelque chose de semblable dans
* les grandes hauteurs, quoique la différence des deux axes soit alors
* moins considérable, & cesse d'être aperc,ûe à la vûe simple.
* Cette petite quantité devoit être de deux secondes sur le Soleil,
* aux environs de midi, pendant le mois d'Octobre dernier, qui est le
* temps où j'ai commencé à observer : cependant, bien loin de trouver
* cette différence, j'ai toûjours remarqué que le diamètre vertical
* étoit plus grand que l'horizontal ; c'est ce dont je me suis assuré
* en appliquant tantôt l'oeil immédiatement à l'héliomètre, & tantôt
* en recevant l'image des deux portions de disque sur une tablette que je
* plaçois en dehors perpendiculairement à l'axe de l'instrument. . . .
* Qu'on mette à une seconde, ou seulement une demi-seconde, le petit excès
* que j'ai aperc,û, ce sera une demi-seconde à joindre aux deux dont les
* réfractions raccourcissent le diamètre vertical. Il suivroit de là
* que ce diamètre seroit plus grand que l'autre de deux secondes & demie
* ou de trois secondes : le Soleil auroit la forme d'un sphéroïde oblong,
* & la différence des deux axes seroit au moins d'une 750e partie." [p.30]
* He decided to suspend judgment until having made observations at
* different altitudes and with heliometers of different focal lengths.
* In examining the limbs more closely, he noticed that the upper and lower
* limbs were less well defined than the lateral ones, and more subject to
* "ondulations importunes". Then: "Lorsque cet inconvénient n'a pas
* lieu, le haut & le bas de l'image sone encore toûjours sujets à une
* gradation de couleurs qui nuit à sa distinction ; à peu près de la
* même manière que la pénombre empêche de distinguer les limites de
* l'ombre avec laquelle elle confine." [p. 31]
* "Si le défaut continuel de netteté des bords supérieur & inférieur
* du Soleil, est très-capable d'embarraser les Observateurs scrupuleux, it
* offre aussi un sujet de problème pour les Physiciens, qui ne manqueront
* pas d'en demander la solution : elle n'est pas difficile à trouver, &
* je crois pouvoir l'indiquer d'une manière sûre. Cette apparence ne peut
* venir que de la décomposition que souffre la lumière en traversant notre
* atmosphère ; les rayons bleus ou violets qui partent en même temps que
* les rayons des autres couleurs, du haut du disque, sont sujets à un peu
* plus de réfraction que ces derniers, ils se courbent un peu davantage;
* ils nous paroissent donc venir d'un peu plus haut, en portant plus loin
* l'illusion ordinaire des réfractions. C'est tout le contraire si nous
* jetons la vûe sur le bord inférieur, nous devons le voir principalement
* par des rayons rouges qui souffrent un peu moins de courbure dans leur
* trajet ; ces rayons, en se courbant moins, doivent frapper nos yeux comme
* s'ils partoient d'un point plus bas, & par conséquent faire paroître
* un peu en dessous la partie inférieure du disque qu'ils étendent,
* pendant que les rayons bleus & violets contribuent à étendre ce même
* disque par sa partie supérieure.
* "Tout ce que nous avançons ici deviendra incontestable, si l'on
* considère plus attentivement l'image du Soleil fournie par une longue
* lunette, & rec,ûe sur une tablette. On verra que la partie de l'image
* qui répond au bord supérieur, est terminée par un trait bleu, pendent
* que le rouge domine sur le bord opposé." [p. 32] -- and he cites
* Delisle's 1715 observation of Jupiter.
* Then he introduces the analogy of the PRISM: "l'explication que nous
* en donnons, est outre cela tout à fait conforme à ce qu'on sait de
* la nature des couleurs, dont la lumière primitive ou celle du Soleil
* est formée. Lorsque les rayons de cet astre pénètrent obliquement
* les différentes couches de la masse d'air qui nous environne, & qui
* sont successivement plus denses, ils doivent être sujets aux mêmes
* accidens que s'ils traversoient obliquement les faces d'un prisme,
* puisqu'ils coupent les couches de l'atmosphère dans des endroits qui
* ne sont pas réciproquement parallèles les uns aux autres . . . ." [p. 33]
* Dated 24 Avril 1748; actually printed in 1752.
* RED RIM on Sun; EARLY MOCK MIRAGES
* "A little before sun-setting, I have often seen the edge of the Sun with
* such protuberances and indentures, as have rendered him, in appearance, a
* very odd figure; the protuberances shooting out far beyond, and the
* indentures pressing into, the disk of the Sun, and always through a
* telescope magnifying fifty-five times, the lower limb has appeared with a
* red glowing arch beneath it, and close to the edge of the Sun, whilst the
* other parts have been clear.
* "At sun-setting, such protuberances and indentures have appeared to
* slide or move along the vertical limbs, from the lower limb to the higher,
* and there vanishing, so as often to form a segment of the Sun's upper limb
* apparently separated from the disk, for a small space of time.
* "At sun-rising, I have often seen the like protuberances, indentures,
* and slices, above described; but with this difference of motion, that at
* sun-rising they first appear to rise in the Sun's upper limb, and slide or
* move downward to the lower limb; or, which is the same thing, they always
* appear at the rising and setting of the Sun, to keep in the same parallels
* of altitude, by the telescope. This property has been many times so
* easily discernable, even by the naked eye, that I have observed the Sun's
* upper limb to shoot out towards right and left, and move downward, forming
* the upper part of the disk an apparent portion of a lesser spheroid than
* the lower part at rising, and the contrary at setting."
* "These protuberances and indentures . . . enabled me to conclude, that
* certain strata of the atmosphere, having different refractive powers, and
* lying horizontally across the conical or cycloidal space traced out by the
* rays, between the eye and that part of the atmosphere first touched by the
* rays, must have been the cause of such apparent protuberances and
* indentures, in an horizontal direction, across the Sun's limbs . . . ."
* Jim Mosher points out that Mr. Samuel Dunn was a prominent cartographer
* and mathematics teacher in this period. He died in 1794.
* PETER DOLLOND's remark about dispersion
* This is mostly about the use of 2 glasses with a common spherical
* surface, placed before the objective (!) of a telescope to correct
* refraction by sliding the concave glass over the convex one.
* But near the end, on p. 335 (mis-numbered 535), he says:
* "It must be observed, that when a star or planet is but a few degrees
* above the horizon, the refraction of the atmosphere occasions it to be
* considerably coloured. The refraction of the lens acting in a contrary
* direction would exactly correct that colour, if the dissipation of the
* rays of light were the same in glass as in air; but as it is greater in
* glass than in air, the colours occasioned by the refraction of the
* atmosphere will be rather more than corrected by those occasioned by the
* refraction of the lens."
* (mentioned, but not cited, by Arago, 1836.)
* WILLIAM HERSCHEL's remarks on atmospheric dispersion
* The remark appears as a footnote to the catalogue of double stars.
* On p.83, Herschel lists entry #107 as "Congerie Stellularum Sagittarii
* borealior" and gives his approximate measurement, with the remark:
* "As accurate as the prismatic power of the atmosphere, which lengthens
* the stars, will permit." At the end of the entry he has the footnote:
* "What I call the prismatic power of the atmosphere, of which little
* notice has been taken by astronomers, is that part of its refractive
* quality whereby it disperses the rays of light, and gives a lengthened
* and coloured image of a lucid point. It is very visible in low stars;
* FOMALHAND, for instance, affords a beautiful prismatic spectrum. That
* this power ought not to be overlooked in delicate and low observations,
* is evident from some measures I have taken to ascertain its quantity.
* Thus I found, May 4, 1783, that the perpendicular diameter of ε,
* FLAMSTEED's 20th Sagittarii, measured 16'' 9''', while the horizontal was
* 8'' 35'''; which gives 7'' 34''' for the prismatic effect: the measures
* were taken with 460, near the meridian, and the air remarkably clear.
* And though this power, which depends on the obliquity of the incident ray,
* diminishes very fast in greater altitudes, yet I have found its effects
* perceivable as high, not only as α or γ Corvi in the meridian,
* but up to Spica Virginis, and even to Regulus. Experiments on these two
* latter stars I made November 20, 1782; when Regulus, at the altitude of
* 49°, shewed the purple rather fuller at the bottom of the field of
* view than when it was at the upper edge; which shews that the prismatic
* powers of the edges of the eye lens were assisted in one situation
* by the power of the atmosphere, but counteracted by it in the other.
* I turned the lens in all situations, to convince myself that it was not
* in fault. This experiment explains also, why a star is not always best
* in the center of the field of view; a fact I have often noticed before
* I knew the cause."
* [Most of the footnote spills onto p. 84.]
* RED and BLUE RIMS ON MARS
* "With a power of 170 and upwards, the disk of the planet appeared much
* elongated, especially when near the horizon; the upper limb was of a fine
* blue, the lower of a deep red." (p.378)
* [reprinted in German in Bode's Astron. Jahrbuch (1819) pp.113-120]
* [and in French, in vol. 5 of Bibliotheque Universelle (at BHL)]
* Stephen Lee, Clerk and Librarian to the Royal Society
* O'C #79
* Wide-ranging discussion of refraction, dispersion, scintillation,
* chromatic scintillation, spectroscopy, etc., with Greek and Latin quotes
* refers to Lee's 1815 paper.
* "Read before the Meteorological Society of London in February and March
* 1824, and published by permission."
* ARAGO's fight with CAUCHY
*
* The trouble began when Cauchy donated to the Academie a copy of his
* work on the theory of light, which contained the claim that gases did
* not show dispersion. Arago noticed this lapse, and tried to correct it
* with a letter, printed under ``Correspondance'' at the end of the 29
* Aug. 1836 meeting:
* "A l'occasion d'un nouveau mémoire de M. Cauchy sur la théorie
* de la lumière, présenté aujourd'hui à l'Academie, M. Arago croit
* devoir signaler une erreur de fait dans laquelle l'auteur est tombé au
* sujet de la dispersion des substances gazeuses. M. Cauchy suppose cette
* dispersion nulle. M. Arago dit, au contraire, qu'elle est sensible et
* qu'il l'a mesurée pour un bon nombre de gaz simples et composés.
* Dans une prochaine séance, M. Arago fera connaître tous ses
* résultats."
* CAUCHY refuses to take his medicine:
* "Il serait assez singulier que l'erreur de fait se trouvât, non dans
* le mémoire lithographié, mais dans l'assertion qu'on vient de lire,
* appliquée, comme elle semble l'être, à ce nouveau mémoire; . . . .
* Ce que M. Arago aura dit, c'est que jusqu'à ce jour les physiciens
* n'avaient point observé la dispersion dans les gaz. C'est là ce que
* j'ai dit moi-même dans la 9e livraison d'un mémoire plus ancien, où,
* après avoir établi et vérifié les lois de la dispersion dans les
* corps solides, après avoir expliqué comment on s'assure que ce
* phénomène disparaît dans le vide, j'ajoute que jusqu'à ce jour on
* n'a pu découvrir dans les gaz aucune trace de la dispersion des
* couleurs . . . . La note insérée dans le Compte rendu prouve
* elle-même l'exactitude de cette proposition à l'époque où
* j'écrivais ces lignes, et c'est parce que les physiciens n'avaient
* jusqu'ici rien découvert à cet égard, que les observations promises
* par M. Arago contribueront notablement au progrès de la science. Mais
* personne ne s'étonnera que je n'aie point parlé de ces observations
* plusiers mois avant qu'elles fussent publiées et peut-être même
* entreprises."
* [printed under ``Correspondance'' for the 3 Octobre 1836 séance.]
* ARAGO lambastes Cauchy for his obstinacy:
* He calls Cauchy's blunder "une erreur de fait capitale," and goes on:
* "En essayant ainsi de détourner M. Cauchy de persister dans la peine
* qu'il se donnait pour déduire de sa savante théorie une conséquence
* que l'observation démentait de tout point, M. Arago croyait avoir droit
* à des remercîments. Loin de là, M. Cauchy s'est montré offensé.
* Son confrère se voit donc obligé d'examiner ses griefs.
* He then documents in detail Cauchy's wrong statements, and quotes
* Cauchy's claim that Arago should have said that the physicists had
* never observed dispersion in gases "to this day". Then: "M. Arago
* déclare ne pouvoir accepter cette rectification ; il montre en effet,
* que la dispersion de l'atmosphère terrestre avait été aperçue
*
* En 1748 par Bouguer
* En 1761 par Lemonnier
* En 1779 par Dollond
* En 1783, en 1785 et en 1805, par Herschel"
*
* and tops this list with his own measurements from 1812, adding:
* "Enfin, en 1815, M. Stephen Lee lut à la Société royale de
* Londres, et publia dans les Transactions philosophiques , un mémoire
* intitulé : Sur la force DISPERSIVE de l'atmosphère et ses effets
* sur les observations astronomiques .
* « Personne, dit M. Cauchy, ne s'étonnera, que je n'aie pas parlé
* des observations de M. Arago, plusiers mois avant qu'elles fussent
* publiées ET PEUT-ÊTRE MÊME ENTREPRISES. »
* A l'insinuation peu bienveillante que ce passage renferme, M. Arago
* répond par deux faits : Ses mesures de la force dispersive de
* l'atmosphère datent de 1812; elles furent citées, quelque temps après
* cette époque, par M. de Lindenau dans le Journal astronomique de
* Gotha . Quant aux mesures de la DISPERSION des gaz et des vapeurs
* que M. Arago avait faites avec M. Petit, son beau-frère, elles
* remontent à 1815 ; on en trouve une analyse détaillée dans le
* premier article du premier cahier du premier volume des Annales
* de physique et de chimie PUBLIÉ en février 1816! M. Arago
* aurait donc, peut-être le droit de remplacer le dernier paragraphe
* guillemetté de M. Cauchy, par le suivant, où quelques expressions
* seulement sont changées :
* « Tout le monde s'étonnera que M. Cauchy n'ait pas connu les
* observations de M. Arago, vingt ans après qu'elles avaient été
* publiées! »
* ARAGO says the effect is well known
* "Les astronomes qui ont essayé, même une seule fois dans leur vie,
* de déterminer la valeur des réfractions horizontales, savent combien
* peu il est permis de compter sur les résultats. C'est ordinairement le
* bord du soleil qui sert de point de mire; mais près de l'horizon, ce
* bord paraît si fortement dentelé, si vivement irisé, si déchiqueté;
* ces diverses irrégularités sone d'ailleurs tellement changeantes que
* l'observateur ne sait où diriger le fil du réticule, à quel point, à
* quel hauteur arrêter sa lunette sur le limbe gradué de l'instrument
* qu'il emploie." (p. 211)
* BESSEL on DISPERSION
* ". . . la loi de la chaleur . . . est évidemment très-variable . . . ."
* "Jusqu'à ce qu'on ait réussi à exprimer cette loi en fonction du
* temps, il sera impossible de former une table qui représente parfaitement
* la réfraction pour chaque distance au zénith et pour chaque temps."
* ". . . quoique l'air parût être parfaitement clair, le rouge et le bleu
* du spectre étaient seuls visibles, de manière que l'étoile resemblait
* en quelque sorte à une étoile double, composée d'une étoile rouge et
* d'une bleu."
* "Il paraît donc que des observations faites dans des distances au zénith
* plus grandes que 85° ne seraient que d'un très-petit poids pour
* l'astronomie, même si l'on pouvait exactement calculer les réfractions
* nécessaires pour les réduire."
* ". . . l'influence des variations de la loi de la chaleur des couches de
* l'air ne commence à être sensible qu'au delà du 85e degré."
* "Au delà de cette limite, c'est-à-dire entre le 85e degré de distance
* au zénith et l'horizon, l'influence des variations de la loi de la
* chaleur des couches de l'air croît rapidement, ce que la théorie
* indique."
* Day-night variations in refraction residuals amount to 30" at 1/2 deg.
* altitude; "Il est évidemment impossible d'expliquer de telles
* différences sans connaître les variations de la loi de la chaleur des
* couches de l'air dépendantes du temps. . . . Mais cela serait un problème
* dont la solution, supposée possible, aurait plus de prix pour la
* météorologie que pour l'astronomie."
* (Many of these remarks are prefigured in his 1823 A.N. paper.)
* ARAGO indulges his penchant for priority disputes and reminds Bessel
* and others that he saw atmospheric dispersion first!
* "M. Arago a rédigé une Note historique où toutes ces recherches sont
* analysées et appréciées." [Was it ever published? Montigny (1855,
* p.55) thinks not; and in Arago's Œuvres Complètes, T. XI, p. 737, we
* read: "Le Mémoire annoncé par M. Arago n'a pas été rédigé. It then
* records his observations of atmospheric dispersion going back to 1811.]
* RED AND VIOLET RIMS PREDICTED (but thought unobservable)
* "Da nun die Strahlen bei ihren Durchgange durch die Atmosphäre
* gebrochen und somit ohne Zweifel auch zerstreut werden, so muss das Bild
* der Sonne ein in verticaler Richtung liegendes S p e c t r u m bilden.
* Unmittelbar ist freilich dieses Erscheinung nicht bemerkbar, dazu ist der
* Zerstreuungswinkel viel zu klein, dem ungeachtet können wir uns das
* Sonnenbild als eine Reihe farbiger Bilder denken, die einander zwar nahe
* aber nicht vollkommen decken, indem das rothe Bild die kleinste, das
* violette hingegen die grösste Höhe über dem Horizonte haben muss,
* woraus sogleich folgt, dass Blendgläser von verschiedener Farbe auch eine
* Verschiedenheit in der beobachteten Sonnenhöhe zur Folge haben werden."
* (He observed only through such colored glasses, so failed to discover
* the green rim.)
* REFRACTION DEPENDS ON STAR COLOR:
* "Wegen der Farbenzerstreuung der Atmosphäre muss bei den
* verschiedenfarbigen Sternen die Refraction etwas Verschieden sein, bei den
* rothen Sternen geringer, als bei den weissen oder grünen."
* ATMOSPHERIC REDDENING AFFECTS APPARENT REFRACTION:
* "Gewöhnlich ist das Sonnenlicht mehr oder weniger roth, wo dann die
* blauen Strahlen grossentheils absorbiert sind. Hieran knüpft sich von
* selbst die Bemerkung, dass die Refraction der weissen Sterne nahe am
* Horizont sich jener des rothen Strahles nähert, vorausgesetzt, dass die
* scheinbare Mitte des vorzugsweise roth erscheinenden Sternes pointiert
* wird." (p.107)
* (Here the double-s is spelled with two small s's.)
* MONTIGNY:
* OBSERVATION OF --> SOLAR <-- COLORED RIMS (over a century after Bouguer!)
* "On sait sans doute, que, si l'on examine au télescope le soleil près
* de l'horizon, une partie des arcs inférieur et supérieur de son disque
* sont colorés, le premier en rouge et orangé, et le second en bleu.
* "Les arcs rouge et orangé qui bordent la partie inférieure du disque
* solaire en s'amincissant à leurs extrémités, près du diametre
* horizontal, sont très-distinctes; le jaune l'est parfois aussi. Le 27
* septembre, le matin, alors que le bord infèrieure s'elevait sur
* l'horizon, l'épaisseur des trois teintes était de 19''.
* "Quand le ciel est pur, on distingue aisément le teinte violette
* indigo au-dessus de l'arc bleu supérieure; elle est parfois
* très-prononcée. Le vert se voit aussi au-dessus du bleu, mais il se
* distingue moins fréquemment." (p.46)
* Also mentions colors in SUNSPOTS.
* NOTE: Read at the meeting of 5 Nov. 1853, but apparently published in 1855.
* An extended German abstract of this paper appeared in
* "Fortschritte der Physik im Jahre 1855", 11, pp. 575-580 (1858).
* (A shorter version appeared the previous year, in FdP 1854, pp. 633-634.)
* O'C #92
* Casual mention of blue and red rims seen at a low-altitude solar eclipse
* The passage is on p. 41; the observation was not understood.
* ARAGO's collected works: unpublished material from his observing logs
* This volume has two title pages, one for the "collected works", and
* one for the "scientific memoirs". So this is Vol. 11 of the "Œuvres
* Complètes" but only Vol. 2 of the "Mémoires Scientifiques".
* Arago's papers were edited by J. A. Barral, and amount to some 20
* volumes in all.
* The discussion of atmospheric dispersion arose from a dispute with
* Cauchy, who incautiously said in 1836 that gases showed no dispersion.
* Arago, who knew better, had to protest; but never published his promised
* review of the subject, nor the details of his own early observations
* that are recorded here. The section on pp. 733-748 is entitled ``Sur
* les pouvoirs dispersifs'' and the section on air beginning on p. 737 is
* called ``Dispersion de l'atmosphère''.
* Most curiously of all, nothing appears here about his observations
* with Biot. Perhaps those were recorded only in Biot's observing logs;
* perhaps Arago felt their publication on the meridian survey was enough;
* or perhaps the later disputes between Arago and Biot were the reason.
* Anyhow, this is useful supplemental material.
* The discussion begins with the dispute with Cauchy (p. 736; see above)
* and he then mentions his own observations of 1812, which he says were
* cited by Lindenau in Journal Astronomique de Gotha.
* The details of these observations appear on pp. 737 ff.:
* "9 mai 1811. -- A 12h 50m de temps sidéral la bordure rouge du
* bord inférieur réel de la Lune était encore bien visible avec le
* groissement de 200 fois (1ee lunette de Lerebours). Le bord supérieur
* réel (inférieur apparent) ne présentait alors que de très-légères
* traces de bleu verdâtre. Avec le groissement de 90 fois la bordure
* rouge était presque invisible; quant au bord inférieure on ne voyait
* pas la moindre nuance de couleurs." He also notices the colored rims on
* Mars, where (I suppose by contrast) the upper limb appeared blue-violet.
* There is then reported an interesting series of experiments to null
* out the dispersion with a prism placed before the eyepiece, while
* looking at the colored rims of the Sun a little before sunset. The
* upper limb appeared "rouge jaunâtre" while the lower (apparent) limb
* was "bleu violacé" -- so I suppose the Sun was still several degrees
* high, though he says nothing about eye discomfort.
* After describing in detail the prisms' deviations and dispersions in
* the laboratory, he concludes that the "dispersive power" of air was to
* that of crown-glass as 10 : 13.04.
* The discussion of the dispersion of air is followed by those of
* various other gases and vapors.
* A half-size scan of this is available at Gallica.
* MONTIGNY's first follow-up note, on dispersion of air
* He uses Cauchy's dispersion formula to calculate refractivity for 2
* additional wavelengths. He mentions the Sun's colored upper and lower
* rims. On p. 534, he gives the difference in refraction of red and blue
* at the horizon as 28''. He assumes the refraction is proportional to
* the refractivity, even near the horizon.
* MONTIGNY's second follow-up note, on solar colored rims
* Here he wants the occasional appearance of red in the blue rim to be due
* to the chromosphere!
* RAMBAUT's DISPERSION paper
* Good historical coverage, going back to Bouguer (1729) and explicitly
* mentioning Stephen Lee (1815) and Montigny (1867).
* This is a lengthy discussion of observations, a few his, mostly others'.
* Not exactly an "early" paper; but it somehow seems to fit in here:
* He compares the Sun's vertical and horizontal diameters on photographs,
* finding the difference to be about 0.17 arcsec times tan Z.
* (The purpose of the original study was to look for polar flattening.)
* Note that this is a side-effect of the colored rims.
* Cf. Bouguer (1748)!
* and the Popular Books file;
* also Biot (1810) in Mirage file
* Biot & Arago (1821) in Mirage file
* Tait (1883) in Mirage file
* Musgrave (1990) in Fake Mirage file
*
* Looks like a false alarm. When I first saw the German version in
* Kiessling's ``Dämmerungserscheinungen'' I thought it might be a
* genuine very early GF report; the phrase "green, such as I had never
* seen before, except in a prism, and surpassing every effect of paint, or
* glass, or gem" sounded promising. But the actual assertion that "there
* were in the immediate neighbourhood of the sinking sun, and for some
* time after his disc had disappeared, large tracts of a pale translucent
* green" makes it sound much more like the green of nacreous clouds.
* Reginald Heber was the Bishop of Calcutta.
* EARLIEST SUNSET GREEN FLASH (pre-1829)?
* The author is identified only as "W.H., R.N. Yeovil, April 22, 1829."
* "I remember once to have noticed the last ray of the setting sun,
* on a fine calm evening at sea, which was of a bright emerald green.
* I believe the fact is noticed by Lord Byron, in some of his works.
* Does not this prove the blue colour of the sea, in the same way that the
* green appearance sometimes observable on each side of the setting sun
* may be accounted for by knowing that his golden rays intervene between
* us and the colour of the blue sky beyond?"
* (The reference may be to Commodore John Byron's 1764 Circumnavigation.)
* In the "Queries and Answers" section.
* Thanks to Google Books for making this discovery possible!
* EARLIEST SUNRISE GREEN FLASH (Jan. 17, 1837)
* (Note that Meinels have both author & title wrong, in "Sunsets. . . " !)
*
* (after mentioning a daylight green meteor he had missed):
* "In the morning however, at a quarter before ten o'clock, while standing
* on a hummock about seventeen feet high, I had observed the upper limb of
* the sun, as it filled a triangular cleft on the ridge of the headland,
* of the most brilliant emerald colour, a phenomenon which I had not
* witnessed before in these regions." (p.191) -- Sir George Back
* EARLIEST SCIENTIFIC ACCOUNT?
* PIETRO GIUSEPPE MAGGI
* This is a long meeting abstract. "The Author had often observed how,
* when the Sun sets behind distant mountains, the last disappearing edge
* is dyed a vivid blue. Because of its long duration, this coloration
* can not be caused by diffraction" but must be due to "the dispersive
* power of the middle air." "The telescope allowed him to know how the
* image of the Sun always appears (besides the well-known flattening)
* fringed with a blue rim in its upper half, and a red one below . . . ."
* "But neither of them has enough width for the naked eye to grasp,
* when, with the solar rays traversing a uniform atmosphere, the image
* suffers no greater alteration than the ordinary flattening mentioned.
* When the equality of temperature and humidity of the air are disturbed,
* new and very visible changes deform the solar disk, and the colored
* borders and then expand, so that the blue becomes clear and distinctly
* seen even by the naked eye . . . ." He mentions Biot's "treatise on
* physical Astronomy" in which "no mention is made of any colored light
* effect," though the distortions of the disk involved are similar.
* "The more notable conditions" involve "separated pieces . . . above and
* below the image of the Sun." So it seems he noticed mock mirages.
* He supposes there are "lenticular masses" of warmer air that are
* responsible, and thinks they are related to the formation of "the clouds
* called cumuli." So he thinks the "appearance of the blue light which
* dyes the last rays of the Sun" is a precursor of "the change of weather
* from clear to rainy."
* According to Pogg., Maggi was born April 30, 1809 and died March 17, 1854,
* not quite 45 years old. He became Professor of Mathematics at Padua in
* 1853.
* Former earliest scientific account. Nice OMEGA drawing
* DISCOVERY attributed to Joseph Baxendell (Pogson's brother-in-law!)
* who had been a sailor -- see obits in Nature 36, 585 (1887) and
* M.N. 48, 157-160 (1888), and (especially) James Bottomley in
* Mem. Proc. Manch. Lit. Phil. Soc. (4) 1, 28-58 (1888).
* N.B.: Title appears only in Index, not on article page.
* "Mr. Baxendell noticed the fact that at the moment of
* the departure of the sun below the horizon, the last glimpse is coloured
* bluish green. On two or three occasions I have noticed this, and also
* near sunset an appearance like what I have rudely depicted.
* Just at the upper edge, where bands of the sun's
* disk are separated one after the other by refraction, each band becomes
* coloured blue just before it vanishes."
* (The referent of "what I have rudely depicted" is an Omega-shaped sunset.)
* A completely garbled abstract appears in Fortschritte der Physik
* im Jahre 1874, 30, 1377-1378 (1879): "Am unteren Rande der wenig vom
* Horizonte entfernten Sonne befand sich eine streifige Wolkenschicht,
* unter der nach dem Horizonte zu die oberen Theile eines Sonnenbildes
* erschienen." [signed Sch. (= Schwalbe), who noticed only the woodcut]
* Fisher #60; not read by him
* O'C #63
* reprint of Joule's letter
* GENUINE AFTERIMAGE REPORT
* Afterimage moves, is smaller than Sun, and "greenish" in color;
* timescale: 10 sec (4 such, gradually fading out)
* EARLY ACCOUNT by David Winstanley (RED and GREEN RIMS isolated)
* "During the past eighteen months the writer, from his residence
* in Blackpool, . . . has noticed the phenomenon of the final coloured ray
* certainly more than fifty times."
* FIRST MENTION of VARIABLE DURATION:
* "The period of its duration too is likewise variable. Sometimes it
* lasts but half a second, ordinarily perhaps a second and a quarter, and
* occasionally as much as two seconds and a half."
* TERMINOLOGY:
* ". . . the phenomenon of the final coloured ray . . . . To the naked eye its
* appearance has generally been that of a green spark of large size and
* great intensity . . . ."
* ". . . the green ray . . . ."
* FIRST USE of term SEGMENT (but not "green segment"):
* ". . . it begins at the points or cusps of the visible segment of the sun . . . "
* EVIDENCE for (but not recognition of) inferior mirage:
* "From the fact of the green cusps being rounded I apprehend that
* irradiation contributes to the apparent magnitude of what is seen."
* FIRST MENTION of (telescopic) CLOUD-TOP flash:
* "That the waters of the ocean have nothing to do with the production of
* the colour is made manifest by its visibility when the sun `sets' behind
* the edge of a well defined cloud. On the 14th and 15th of June, for
* instance, it was seen at upper contact of the solar limb with clouds.
* . . . And on several other occasions the writer has observed the effect
* when the disappearance of the sun has taken place at an elevation of
* six or eight degrees behind a heavy bank of clouds."
*
* "Of the objective nature of the phenomenon it is needless to offer
* evidence; for it needs to be but seldom seen to preclude the idea of an
* optical illusion."
* "The different colours seen, together with the order of their
* appearance, are suggestive of the prismatic action of the atmosphere as
* the cause of their production."
* (verified telescopically by using an artificial occulter)
* "I apprehend that the results here given sufficiently prove that
* atmospheric refraction is the cause of the coloured rays seen at the
* moment of the sun's departure below the horizon."
* O'C #160
* Joule and Winstanley quoted in Nature -- but without Joule's figure!
* Fisher #161, O'C #161
* Nature's reprint of Winstanley's paper, abstracted
* JULES VERNE's FIRST mention of the "green ray" (1877)
* This novel is set mostly in a coal mine -- in Scotland! The heroine
* has spent her whole life underground, and is about to see her first
* sunrise, in Edinburgh:
* "Enfin, un premier rayon atteignit l'oeil de la jeune fille. C'était
* ce rayon vert, qui, soir ou matin, se dégage de la mer, lorsque
* l'horizon est pur." [This is in Chapter XVII, "Un Lever de Soleil".]
* I have seen only the 1967 Hachette edition, where this passage occurs
* on p. 186. Interestingly, the biographical note at the end (on
* unnumbered pages) claims that "Le physicien et astronom Jules Janssen,
* le mathématicien Joseph Bertrand refont les calculs de Jules Verne --
* et vérifient, dit-on (il serait sans doute imprudent de ne pas placer
* ici un point d'interrogation), l'exactitude des courbes, paraboles et
* hyperboles qui définissent le trajet du boulet-wagon de De la Terre
* à la Lune ."
* As Verne went to Scotland in 1859, and was much taken with the place,
* it seems likely that he may have seen green flashes there: both his
* mentions of the flash are set in Scotland. Also, this book is full of
* talk about how superstitious and full of folklore the Scots are; so the
* invention of the ``legend'' later on seems more natural.
* Thanks to Hezi Yizhaq for pointing this out!
* James Anthony Froude's flash of Aug. 28, 1874
* FIRST USE of "FLASH" ??
* Froude was a controversial historian and excellent writer. This is
* from the section of his book called ``Leaves from a South African
* Journal.'' While sailing to South Africa, he says:
* "The sea calm as Torbay in stillest summer. . . . Last night we had a
* remarkable sunset. The disk, as it touched the horizon, was deep
* crimson. As the last edge of the rim disappeared there came a flash,
* lasting for a second, of dazzling green -- the creation I suppose of my
* own eyes."
* He also tells many poignant stories of South Africa, and saw Kimberly
* in the early days, when the mine was only 120 feet deep.
* An older brother, William Froude, was an engineer and naval architecht
* who devised the Froude Number of hydrodynamics. The family name rhymes
* with "food"; many supposedly authoritative websites get this wrong.
* Many thanks to Agnes McLean for finding this!
* The "BLUE SPARK" quote traced to its source!
* Lt. Claude Reignier Conder of the Royal Engineers was in charge of the
* survey of Palestine in 1872-1875, when he turned the work over to Lt.
* H. H. Kitchener (later to become an Earl, and controversial for his
* use of concentration camps in South Africa -- but this was the young
* Kitchener's first job in the Royal Engineers). On pp. 264-265, Conder
* describes a sunset and sunrise observed from the top of Mt. Hermon,
* including the TRIANGULAR MOUNTAIN SHADOWS. But our interest is in a
* single sentence, set off as a separate paragraph:
* "The sun underwent strange changes of shape in the thick vapours --- now
* almost square, now like a domed temple --- until at length it slid into
* the sea, and went out like a blue spark."
* MANY THANKS to Andrew Alden, of Oakland, CA, for finding this!
* According to Wikipedia, Mount Hermon is 2,814 m above sea level, and
* the highest point in Syria. Conder says his observation was made from
* a height of 9150 feet. It appears to have been made on "Monday, the 8th
* of September" (1873).
* Available at
* https://archive.org/stream/tentworkinpalest01conduoft#page/264/mode/2up
* and
* https://books.google.com/books/about/Tent_Work_in_Palestine.html?id=ltiQteXzxNIC
* Henry Bedford's pre-Verne observation
* sunset and sunrise of July 14/15, 1878: ". . . the sun -- the green
* sun --- appears. A distant low range of rocks comes between us and its
* point of rising; and, as we glide on, an opening between them shows us
* the sun, a bright emerald, as pure and brilliant as ever gem that
* glistened; again we lose it, and again an opening shows it to us in
* its own golden light; and then once more it is the bright green; and
* now it rises higher, clears the ridge, and is once more the golden orb.
* This is what we saw, but another observer, our alter Ego , assures us
* that, when he first saw it, the colour was a fiery red, which soon turned
* to green. Evidently an optical effect of what is called polarization
* of light, as these complementary colours seem to show." (p.48)
* Bedford's long travelogue was serialized in Month 34, 290-304 (Ch. I),
* 395-411 (Ch. II) (1878); vol. 35, pp.43-58 (Ch. III), pp.167-184 (Ch.IV),
* 334-351 (Ch.V), 473-490 (Ch.VI) and vol. 36, 17-37 (Ch. VII) (all 1879).
* N.B.: these are volumes XV to XVII, New Series.
* Bedford was a convert to Catholicism; The Month appears to have been a
* magazine for British Catholics.
* JULES VERNE's NOVEL
* I was surprised to discover, from the facsimile of the original edition
* that was published by Hachette in 1977, that the original title was
* hyphenated. The Hachette edition also has the original illustrations,
* including drawings depicting the "ray" like narrow crepuscular rays;
* see Mulder's complaint about this on p.3 of his book.
* Cf. Moncrieff's complaints (1905) about Scottish errors.
* Thanks to Stephen Williams for turning this up!
* Fisher #144, O'C #145
* For the origin of the "legend", see the 2002 publication of Verne's
* correspondence with Hetzel, his editor -- and its actual inventor.
* (Quoted in its entirety in Rambaut's 1906 Met.Mag. paper)
* ". . . the parting ray is a brilliant emerald green."
* "The . . . effect is not produced by the sun setting behind a distant bank
* of clouds. Probably the first ray from the rising sun would be the same
* unexpected colour."
* Fisher #58
* former "EARLIEST" OBSERVATION (Sept. 13, 1865)
* William Swan observed from summit of the Rigi.
* misinterpreted as due to contrast with red sky:
* "I do not doubt the phenomenon was purely subjective, for before sunrise
* the sky was all lit up of a magnificent crimson hue."
* NOTE: This is the William Swan for whom the "Swan bands" of C2 are named.
* Fisher #141, O'C #135
* Mostly about the Krakatoa effects, but half a paragraph on GF
* (pp.601-602) says "Mr. Henry Bedford . . . in an English magazine" of
* 1878, as well as G.H.Hopkins (see above). The Bedford quote describes
* an Arctic Circle sunset and sunrise in July: ". . . the sun -- the GREEN
* sun --- appears. A distant low range of rocks comes between us and its
* point of rising, and, as we glide on, an opening between them shows us
* the sun, a bright emerald, as pure and brilliant as ever gem that
* glistened; . . . and now it rises higher, clears the ridge, and is once
* more the golden orb." (slightly mis-quoted; see Bedford, 1879)
* The Bedford quotation is pre-Verne, but no detailed citation is given.
* (in the March issue)
* Thinks it is a CONTRAST EFFECT
* "A sun seen as green or blue for hours together is a phenomenon
* witnessed only after the late Krakatoa eruptions . . . ; but a sun which
* turns green or blue just at setting is, I believe, an old and, we may say,
* ordinary one, little remarked till lately. I have a note of witnessing
* it . . . on June 23, 1877, the sunset being very clear and bright.
* "The sunset was bright this evening, the sun of a ruddy gold, which
* colour it kept till nothing was left of it but a star-like spot; then this
* spot turned, for the twinkling of an eye, a leaden or watery blue, and
* vanished."
* a GEOMETRIC CRANK -- one of de Morgan's ``paradoxers''
* Starts off by mentioning Verne's novel, and quoting the florid paragraph.
* A wonderfully ingenious and completely CRANK THEORY OF COLOR is used to
* explain the green ray as the COMPLEMENT of the INVISIBLE INFRARED rays!
* It all is based on a confusion of additive and subtractive color mixing,
* together with the mistaken notion that the spectrum contains all possible
* colors. From these mistakes, he goes on to a marvelous GEOMETRIC
* CONSTRUCTION, and hence a mechanical device to illustrate the theory:
* "Ce petit instrument . . . donne, dans la practique des résultats
* beaucoup plus exacts que le cercle chromatique de Chevreul. . . ."
* ". . . il serait particulièrement curieux de blanchir une partie de
* l'espace v'v'' avec des rayons obscurs et, inversement, de rendre
* lumineux les rayons obscurs en les mélangement avec des rayons verts."
* [Indeed it would be!]
*
* NOTE: La Nature published 2 "Semestres" per year,
* BOTH with the SAME volume number, and both starting at p.1 !!
* Extreme care is required to determine the correct half of the year;
* either the date or the issue number must be given.
* AUGUSTE TREVE's observations and simultaneous-contrast theory
* (This was the great-uncle of the modern scientist Yvain Treve)
* "Sa durée est celle d'un éclair. C'est, pour le navigateur, comme un
* adieu chargé de promesses, toujours fidèlement tenues, d'un beau temps
* pour le lendemain; il est, en effet, bien peu d'exemples, s'il y en a,
* qu'un beau coucher de soleil ait été suivi d'un mauvais temps."
* Cf. the similar claims made by Wegener (1926), and the remark of
* "Another Engineer Officer" (1904) about this being standard French
* navigational instruction lore.
* Fisher #142
* Almost word for word the same letter published in C.R.
* cited by Polo in his 1904 letter
* A short followup to the Trève paper of Oct. 1885
* He offers a mechanical theory for successive contrast!
* Thanks again to Yvain Treve for providing this reference!
* One-paragraph abstract of the 1885 Trève paper in C.R.
* "M. Trève has described to the French Academy of Sciences a phenomenon
* of a beautiful green ray which he has observed . . . ."
* Besson's sunrise observation, with a VENUS flash on setting as well
* A convert from the "contrast" idea, thanks to seeing a sunRISE flash
* in the Azores: "Voici une excellente occasion de vérifier la théorie
* du commandant Trève." He saw another (not as good) the next morning.
* "La théorie du contraste des couleurs me paraît donc fausse."
* This is Vol. 22 of the 3rd Series, 1er Semestre, dated 3 Avril 1886
* in the section "Correspondance et Chronique".
* Available at Gallica.
* SUNRISE OBSERVATIONS OVER MOUNTAINS in letter to Mascart
* "Tous les touristes qui frequentent l'Égypte et la mer Rouge ont été
* témoins de ce phénomène . . . ."
* ". . . dans le mer Rouge, plusiers fois et notamment en octobre dernier,
* j'ai assisté, moi et mon second, au lever du Soleil à l'horizon de
* la mer, et que la première impression sur nos deux rétines a été
* d'un beau vert émeraude.
* Le lendemain, assistant tous deux au lever du Soleil derrière des
* montagnes élévées de 1° à 2° au-dessus de l'horizon, la même
* impression lumineuse franchement verte a encore frappé nos yeux."
* [Note the correct altitude here, but not in his 1898 letter.]
* "Je ne puis citer le nombre de fois que j'ai observé et fait observer
* ce même phénomène au coucher du Soleil et encore derrière des
* montagnes."
* Fisher #87, O'C #237
* This is an extract from the C.R. letter
* No.707, 18 Dec. 1886
* O'C #238
* Fisher #88
* de Maubeuge's letter quoted again, in l'Astronomie
* This was *before* it merged with B.S.A.F. The full title is:
*
* L' A S T R O N O M I E
*
* REVUE
* D'ASTRONOMIE
* POPULAIRE,
* de Meteorologie et de Physique du Globe,
* exposant
* les progrès de la science pendant l'année;
* publiée par
* CAMILLE FLAMMARION,
* avec le concurs des principaux astronomes français et étrangers
* FIRST USE of term "GREEN FLASH"?
* "At sunset tonight I observed a phenomenon which has, I believe, been
* seen from on board ship, but never probably from a place with such a
* distant sea horizon as we have here -- some seventy miles. The sky for
* a short distance above the point where the sun set was perfectly clear
* of cloud or haze, and I watched carefully the last portion of its disk
* disappear into the sea. As soon as the last speck of the yellow
* vanished, a momentary bright green flash shone out. This was quite
* different from the complementary green seen after looking at the setting
* sun; brighter and bluer in tint. I have seen it stated that the cause
* of this green light is the sun shining through the water that hides
* it, and would be glad to know if such is the true explanation."
* Robert Trail Omond was a Scottish meteorologist, Superintendent of the
* Ben Nevis Observatory (1883-95) when this was written, and later (1903-?)
* Honorary Secretary of the Scottish Meteorological Society [see WW, 1909].
* Fisher #111, O'C #99
* RICCO's reply to Omond
* Fisher #126, O'C #116
* Early description of GREEN RIM
* FIRST refutation of CONTRAST EFFECT by HUE ?
* ? Joseph Solange Henri Pellat (Pogg.)
* ". . . ni à un contraste des couleurs qui, du reste, vu la teinte jaune
* d'or du disque, donnerait une couleur bleue et non pas verte."
* Pellat's report, in German
* Here is an explicit mention of THOLLON:
* "During the autumn of 1886 I visited M. Perrotin and M. Thollon, at the
* Nice Observatory, and watched the setting sun with M. Thollon on five
* clear evenings, to catch sight of the last blue ray . . . . The sun at that
* period of the year set over the bare edge of an opposite mountain, but on
* four out of the five nights I saw the blue ray, though I have only seen it
* on two other occasions from the sea-level."
* (article is mostly about Lick Obs.)
* N.B.: A. Cowper Ranyard was editor of "Knowledge" from 1904-1910;
* the editor when he published this article was R.A.Proctor.
* Ranyard was apparently impressed by John Evershed, who inherited
* Ranyard's instruments in 1894, after knowing him only a year.
* I see from the Nov. 13, 1863 issue of M.N. that Ranyard became a Fellow
* of the RAS at that time -- as Foucault and Bond became Associates.
* Fisher #124
* The ENGLISH MECHANIC series for 1889 follows.
* Note that Eng.Mech. published 2 volumes per year.
* The "Letters" section of E.M. occupied the ecological niche today held
* by Usenet: a heterogeneous mixture of professionals, amateurs, and cranks.
* Letter-writers often used only initials, or pseudonyms.
* Letters are numbered in squared brackets; I preserve those numbers here,
* as many letters in small print appear on each 9 x 12-inch page.
* One letter may touch on many topics besides the GF; rather than list the
* many irrelevancies, I simply give the number. Note that queries and
* letters have separate numbering systems!
*
* This thread was started by someone signing as "F.R.A.S." (i.e., "Fellow
* of the Royal Astronomical Society") in a previous issue. Here, "H.B.F."
* asks "F.R.A.S." for an explanation of the "Green Ray" at sunset, which
* he describes as "a drop of the most vivid emerald green". He continues:
* "My attention was first drawn to the alleged phenomenon by the perusal
* of M. Jules Verne's story, `The Green Ray,' and believing it to be
* fictitious, I set myself to observe. For about three months of the summer
* the place of my residence -- an island in the Levant -- allowed an ocean
* horizon for the setting sun. On the very first evening of observation I
* was rewarded with the sight of that wonderfully brilliant flash, and on
* successive evenings I continued the observations. About two out of every
* three observations were successful . . . . Believing that the phenomenon
* might still be a purely subjective one, I asked my wife to join in the
* observations, and, sceptical as she at first was, on each occasion,
* whether the green ray was visible or not, our observations exactly
* coincided. On the whole, out of some fifty successive observations, I
* should say we succeeded in obtaining a glimpse of the `ray' about thirty
* times."
* Eric Hutton identifies "A Fellow of the Royal Astronomical Society" as
* Captain Noble, J.P. of Uckfield, Sussex. [EM ref. No. 3105 p326]
* No. 1275, Aug. 30, 1889
* Fisher #167
* Alas, the otherwise reliable Fellow offers "H.B.F." the AFTERIMAGE theory!
* (Evidently, he had never seen a GF)
* "I fancy that the green ray of which my querist speaks must have a
* cognate origin to this, and that the eye, deadened to the sensation of red
* by the brilliant crimson of the sun's disappearing limb, must temporarily
* select the green from the more composite light illuminating the horizon."
* Eric Hutton identifies "A Fellow of the Royal Astronomical Society" as
* Captain Noble, J.P. of Uckfield, Sussex. [EM ref. No. 3105 p326]
* No. 1276, Sept. 6, 1889
* Fisher #172
* Another ignoramus offers the "WAVE" notion:
* "Surely the `emerald drop' so often seen by `H.B.F.' page 11, can be no
* other than solar light transmitted through the sea . . . ."
* No. 1276, Sept. 6, 1889
* Fisher #164
* Another vote for afterimages:
* He cites the Pears' Soap ads as an example.
* No. 1277, Sept. 13, 1889
* "H.B.F." knows it isn't an afterimage:
* "I should have explained, however, that I failed to observe it on
* occasions when the sun presented a red appearance, and only when he set
* with a pale golden colour has it been visible. Moreover the ray has
* not that dull appearance noticeable in this and in other similar optical
* illusions, nor has it the like permanency."
* He also rejects the light-through-a-wave explanation of "E.L.G.", as
* ". . . only when the sea has been exceptionally calm, has it been visible."
* COMMENT: Note that the experienced observer here quite rightly dismisses
* the arm-waving of the would-be theorists who have *never* seen a flash.
* No. 1277, Sept. 13, 1889
* Fisher #168
* Another vote for afterimages:
* "I may, however, add that if this is the correct explanation, the
* phenomenon is more likely to be observed within the Tropics than at higher
* latitudes, since the more vertical the path of the setting sun, the
* greater the rapidity of its apparent motion, and the more sudden the
* change from light to darkness."
* No. 1277, Sept. 13, 1889
* FRAS switches to the "wave" idea:
* cites HBF's 30351 letter
* Eric Hutton identifies "A Fellow of the Royal Astronomical Society" as
* Captain Noble, J.P. of Uckfield, Sussex. [EM ref. No. 3105 p326]
* No. 1278, Sept. 20, 1889
* Fisher #173
* BLUE is commonest color at sea?
* Believes flash is due to Sun shining through water
* "I have had numberless opportunities of witnessing the same appearance
* in mid-ocean, where the water appears blue, and the flash is also of an
* exquisite blue."
* "I have repeatedly drawn the attention of others to this, especially
* between the Tropics, to all of whom the flash appeared blue."
* cites E.M.50,11
* No. 1278, Sept. 20, 1889
* Fisher #166
* cites and quotes Ranyard's paper in Knowledge
* No. 1278, Sept. 20, 1889
* O'C #114
* "E.L.G." criticises "F.R.A.S." for afterimage theory
* ". . . no sunset, in any latitude, has a colour complemental to green."
* He now recognizes the problem with his model:
* "The emerald light must somehow have got a dip through sea-water; but
* how, is a great puzzle with so little refraction. It would seem, it
* must enter and leave very steep wave surfaces, though `H.B.F.' calls the
* sea `calm.' He does not give a hint of the height of his station, a most
* important element, if it is never, as he thinks, visible from a ship's
* deck."
* No. 1278, Sept. 20, 1889
* Fisher #165
* HBF's 3rd letter: he decides to accept the "wave" story, but modified:
* ". . . the last glimpse of the sun after he has passed beneath the visible
* horizon, seen through the depth of a clear and placid ocean , and not
* through a mere superficial wave or two." [N.B.: ignores refraction!]
* "The verandah from which most of my observations were made stands 664ft.
* above sea-level, at a distance of three miles from the shore."
* No. 1279, Sept. 27, 1889
* Fisher #169
* At last, "E.L.G." puts the pieces together!
* "If this is, after all, a blue ray, and can be seen, as the observer at
* Nice tells us, after sunset behind a mountain, of course the sea has
* nothing to do with it. The last explanation must be taken, and it gives us
* the first proof that air, like other refracting media, refracts the
* different colours with different indices. Now I believed, about thirty
* years ago, that I had a proof of this on watching, through a good
* achromatic glass, a very clear sunrise in the north suburbs of London.
* The sun rose . . . with so little colour that it could not be called even
* `pale golden.' It was merely creamy; but from the first emergence till
* the lower limb was up, the upper limb had a distinct edging of blue, and
* the lower one of red."
* (So we have here an independent, if uncertain, rediscovery of the colored
* limbs.)
* With this item, the *green* ray series ends. But see the next 2 items!
* No. 1279, Sept. 27, 1889
* A. COWPER RANYARD speaks up:
* "I need only remind `F.R.A.S.' of a paper by Sir G. B. Airy, published
* in the Monthly Notices for 1869, on an eyepiece for correcting the
* effects of atmospheric dispersion, to recall to his mind the phenomena
* which are always observed when a star or the sun is near to the horizon."
* "When the sun or a planet is near to the horizon the blue fringe along
* its upper limb and the red fringe along its lower limb is a very marked
* feature when it is observed with a power of two or three hundred."
* The Airy paper is probably O'C. #4
* FIRST CALCULATION SCALED TO HORIZONTAL REFRACTION ? (1/60)
* "To express it in numbers, the atmospheric dispersion from B to G of the
* spectrum is about one-sixtieth of the atmospheric refraction. On the
* horizon at the sea-level, the horizontal refraction is about 34 minutes,
* and the length of the spectrum from B to G is 34''."
* He favorably notes "E.L.G."'s observation.
* No. 1280, Oct. 4, 1889
* Fisher #125
* "FRAS" recants, with an excuse, and a damning admission:
* "There can be no doubt that Mr. Ranyard does suggest a -- or the --
* vera causa for the phenomenon of the final blue flash incident on
* sunsets; but, as far as I am concerned, it is one which I have never
* witnessed . . . ."
* [NOTE: Both this and Ranyard's item were indexed under "blue" by the E.M.]
* This apparently ends the entire episode in E.M. for 1889.
* No. 1282, Oct. 18, 1889
* Fisher #174
* Possible GREEN RAY ?? or BLANK-STRIP flash?
* ". . . den Eindruck eines vertikalen blaugrünen Flämmchens . . . "
* "Ziemlich nahe vor Sonnenuntergang war hier die Sonne durch einen
* schmalen Wolkenstreifen in zwei Theile getheilt. . . ."
*
* Leonhard Sohncke (1842-1897) was a well-known crystallographer who
* became head of the meteorological stations in Baden when he was made
* professor of physics at the Technische Hochschule in Karlsruhe (1871-1883).
* His green-flash work is rather obliquely mentioned in the DSB.
* Fisher #138
* Sohncke's paper reported in Nature; cited by Michie Smith (see below)
* March 27 issue
* Fisher #139
* Nature's report of Sohncke's paper re-reported in Science
* in the "Notes and News" department, which began on the previous page.
* April 11 issue
* SECOND MENTION OF VARIABLE DURATION
* "If the colour were due simply to refraction it would last for only a
* fraction of a second, and the colour would be much more blue than green.
* But, so far as my own observations go, the colour may last for several
* seconds, and is a bright pea-green . . . ."
* Charles Michie Smith's first appearance. He was Pogson's successor at
* Madras, and established the Kodaikánal Observatory in 1899.
* Note that Evershed, his successor, always refers to him as
* "Michie-Smith" (hyphenated) in his autobiographical note in Vistas,
* Vol. 1, p.33.
* Fisher #136, O'C #285
* April 10 issue
* GREEN RAY
* ". . . the sun had sunk behind a hill, when, suddenly, my companion and I
* both saw a flash of green light against the thickest cloud; it lasted
* one or two seconds, just long enough for there to be no doubt about it.
* We compared it to the glare thrown by `green fire,' extending over an
* area whose diameter appeared about four times that of the moon."
* Fisher #39
* First calculation of duration of green at sunset ?
* 2nd CALCULATION SCALED TO HORIZONTAL REFRACTION ?
* "Cette dispersion atmosphérique démontre que, dans un coucher de
* Soleil, le rayon vert doit persister, sour notre latitude, une
* seconde environ après la disparition du rayon jaune."
* (Prosper Henry)
* The Henry brothers, Paul and Prosper, invented the 13-inch astrograph
* used to make the Carte du Ciel , the monster project that absorbed the
* efforts of a whole generation (or two!) of astronomers.
* Fisher #55, O'C #50
* cited by F.K., who blames Fisher
* This is about crepuscular rays, NOT green flashes!
* Biart's letter is confined to p.116; but the editorial comment on the
* next page is included here.
* This was *before* l'Astronomie merged with B.S.A.F.
* Fisher #8
* SUNRISE better than SUNSET (according to Charles Mostyn)
* NO GF under INVERSION conditions; TWO TYPES of sunsets distinguished
* "The best displays took place took place when the refraction near the
* horizon was of such a character that the sun assumed a balloon, or vase,
* shape as he came close to the sea-line. When, on the contrary, the sun
* appeared flattened out in its horizontal diameter, the `green ray' was
* either entirely absent, or was seen only in an indistinct and uncertain
* manner."
* Seen 3 times as the ship rose and fell on waves in "the Southern Ocean."
* Apparently, this refers to Mostyn's trip from London to Sydney at the end
* of 1890 and beginning of 1891 (thanks to Edward Gilbert for the info!)
* This is the Aug. 13 issue.
* Fisher #103, O'C #253
* Mostyn's note reprinted (with slight editing) in "Science"
* Sept. 18, 1891 issue; the column runs from pp. 157-159.
* The 1891 E.M. series begins with E.Reginald Blakeley, who saw a
* crepuscular ray:
* "Surely it could not be the green ray Verne has written about?"
* No. 1379, Aug. 28, 1891
* A reply to E.Reginald Blakeley, pointing out that what he saw were
* crepuscular rays (though not so named).
* No. 1380, Sept. 4, 1891
* HBF's 4th letter: he continues to accept the "wave" story:
* "I have not the least doubt but that the explanation of the phenomenon
* given by `E.L.G.' (letter 30324) is the correct one . . . ."
* But there is a nice account here of a double flash at sunset made
* visible by "the sea . . . swelling in great easy rolls."
* No. 1380, Sept. 4, 1891
* Fisher #170
* Mostyn's Nature letter replayed by Scientific American
* Sept. 12 issue -- must have been a weekly then.
* Packer points out that crepuscular rays are often mistaken for green
* flashes and other things, citing Col. Markwick's letter in No.1281.
* No. 1383, Sept. 25, 1891
* Blakeley thanks Clapham and "HBF", agreeing that he saw a crepuscular ray
* and not a GF.
* No. 1383, Sept. 25, 1891
* A minor GF observation (blue, actually) from Mt. Hamilton
* This is probably an observation of a flash above a Wegener's
* "BLANK STRIP", from the description. The dark strip in the drawing is
* about 2 degrees above the apparent horizon, roughly right for the dip
* there.
* Fisher #33
* William N. GROFF's work on ANCIENT EGYPTIAN depictions
* contains some of his own observations
*
* Groff was an interesting character about whom little is known. He was
* born in 1857 in Cincinnati, Ohio, and died relatively young in 1901 in
* Athens, Greece. I'd guess he picked up his astronomical interest in
* Cincy, as the observatory there was important in the mid-19th Century.
*
* He was obviously an experienced GF observer; so we take his GF work
* seriously. He seems to have learned most of his astronomy from
* Flammarion's "Astronomie Populaire" and Burritt's "Geography of the
* Heavens". With such a weak scientific background, it is remarkable that
* he managed to figure out the correct cause of the GF on his own.
*
* Note that he describes the green flash at sea as ``le `soleil vert' des
* matelots,'' which confirms my opinion that these phenomena were long known
* to sailors.
*
* N.B.: Each volume, or "No." as it is called, was printed in the year
* after the date of the meeting in which the paper was given. Thus
* "1893" here really means "given in 1893, published in 1894".
* Fisher #50; O'C #40
* comment on Groff's paper
* Dr. Abbate pacha thinks it is an afterimage.
* His comment that "Newton . . . a été le premier à parler de ce
* phénomène intraoptique, tout en le rapportant au changement qui
* survient du rouge intense à la couleur complémentaire, le vert"
* seems to have given rise to a mistaken impression that Newton commented
* on green flashes, not just on afterimages.
* Dr. Abbate seems really to be the FIRST to believe the Verne "LEGEND":
* ". . . le charmant petit livre a J. Verne, Le Rayon Vert . . . . Ceux qui
* le consulteront, sûrement avec plaisir, trouveront comme récompense,
* outre la délicate illusion qui est produite par la peine d'observer
* attentivement le phénomène du rayon vert , un bonheur ineffable,
* mystique, qui s'y rattache, selon la vielle légende, née au pays des
* Highlanders, en Ecosse."
* O'C #1
* Groff's 2nd paper
* This is the second of two notes published as a single item; the first is
* on the Nile. These notes were additions to earlier papers.
* Fisher #51; O'C #41
* Groff's 3rd paper
* This is a short note mentioning the green flash, but associating green
* and blue with the "other world" and death (via the setting of the Sun).
* [Note that the "III" here means it is the third note in this group, not
* the third in the GF series (though it is that as well).]
* Groff's 4th paper
* This is a short note giving further examples.
* Popular summary of Groff's work
* in No.531, 30 Mars 1895
* Daressy objects to Groff's view that the Egyptians meant to depict the
* green flash: "Est-il probable qu'en peignant ainsi le caractère
* hiéroglyphique, les Egyptiens aient eu l'intention de représenter
* le phénomène du rayon vert? Plusiers arguments me semblent indiquer
* que telle n'a pas été leur pensée."
* Unfortunately, his second reason is that "On sait que le rayon vert est
* un phénomène dû à une illusion d'optique . . . d'une durée
* infiniment courte . . . ." -- and, as "mon honorable confrère parle d'un
* rayon vert au lever du soleil" when Daressy thinks "Les conditions
* requises ne se trouvent plus réunies: l'astre étant plus brillant que le
* ciel, son apparition ne peut donner lieu à une impression lumineuse de
* couleur inverse . . . ." Worse, he asserts that "Ce ne peut donc être que
* par une prédisposition spéciale aux illusions d'optique, une sorte de
* daltonisme, que certaines personnes croient voir le disque émettre une
* lumière verte à son lever." [Talk about adding insult to injury!]
* "Si donc les Egyptiens n'ont pas représenté le rayon vert avec le
* soleil couchant, il est fort improbable qu'ils l'aient reproduit avec le
* soleil levant."
* Fortunately, his later arguments are sounder; he argues that the colors
* are chosen for religious rather than observational reasons, and that
* the "sunrise" symbol is derived from the rounded shape of a box lid.
* MRS.STEEL's NOVEL
* "And Marjory, cresting the knoll, thought instantly that here, indeed,
* was a chance of the Green Ray. For ever since she had read Jules
* Verne's book the idea of this, the last legacy of a dying day, had
* remained with her fancifully. . . . Even if the legend was no legend, and
* the phenomenon simply a natural one, due to refraction, there must be
* something exhilirating in seeing that which other people had not seen
* . . . ." (p.125)
* "`I have often heard you mention this Green Ray, Miss Marjory, but I am
* not quite sure to what you allude.'
* `To a fiction of Jules Verne's, that is all,' put in Paul quickly.
* `Nothing of the sort; people have seen it,' corrected the girl,
* eagerly." (p.161)
* " `. . . it is like the Green Ray, something to dream about.'" (p.162)
* Fisher #140 says "Flora Annie Steel" but not read
* Groff's 5th paper
* This is his long paper that discusses the green flash in detail.
* GOOD QUOTE:
* "En traitant des questions scientifiques on rencontre deux difficultés:
* si l'on se borne à annoncer les résultats des recherches, on court le
* risque d'être obscur, ou même d'être incompris; si l'on donne, en
* détail, des preuves à l'appui de chaque assertion, on se perd dans des
* digressions et on court le risque d'être inintelligible."
* Well said! So, "Peut-être la meilleure méthode est-elle, tout en
* donnant les résultats des recherches, d'indiquer brièvement sur quoi
* elles sont fondées, puis, si l'occasion s'en présente, de discuter plus
* en détail le sujet et de développer à l'appui des conclusions ce qu'on
* n'avait fait qu'indiquer." So Daressy's note gives him this
* opportunity.
* TERMINOLOGY:
* "Nous disons rayon , mais il serait plus correct de dire
* zone lumineuse , zone lumineuse rouge, orange, jaune, verte, bleue
* (indigo ou violet), qui s'appliquerait à la lumière (en apparence)
* émise par le disque du soleil à l'horizon, et que differentes personnes,
* sur une même méridienne observeraient simultanément."
* Regarding AFTERIMAGES:
* "Si l'on regarde un objet rouge ou rougeâtre -- le disque du soleil,
* par exemple, puis qu'on ferme les yeux, on peut bien voir la couleur
* complémentaire verte ou verdâtre, mais on distingue bien entre le
* phénomène d'optique et la couleur verte du disque du soleil apparaissant
* ou disparaissant -- la sensation est tout autre."
* The TURNING-AROUND EXPERIMENT (this seems to be the FIRST mention of it):
* "Si plusiers personnes A, B et C par exemple, vont constater la couleur
* du dernier rayon du soleil couchant, A regarde le soleil, B et C ont le
* dos tourné vers l'occident; quand A voit la dernière partie du disque
* disparaissant prendre la couleur verte (ou bleue); il dit à B et C de
* regarder; B et C, qui n'avaient pas regardé le disque tournent et peuvent
* bien voir le disque disparaissant de couleur verte (ou bleue), mais est-ce
* à dire qu'on ne voit jamais la couleur complémentaire au moment du
* coucher du soleil? je crois l'avoir constatée, mais la sensation est tout
* autre que celle produite sur l'observateur par la couleur réelle, ou
* apparent du disque."
* HISTORY:
* ". . . j'avais espèré trouver le phénomène étudiée et expliqué dans
* des ouvrages et avoir, ou la confirmation de l'hypothèse à laquelle
* j'étais arrivé, ou la vraie explication. Mais, malgré toutes mes
* recherches, je n'ai rencontré nulle part l'étude du phénomène du
* premier et du dernier rayon (zône lumineuse) du soleil à l'horizon sur
* le désert. Mais assurément le phénomène des couleurs du soleil à son
* lever et à son coucher sur le désert a dû être étudié et expliqué
* et j'espère pouvoir compléter plus tard les indications données ici à
* ce sujet: la seule indication directe que j'aie rencontrée jusqu'ici est
* dans Jules Verne, Le Rayon vert, p. 181 s. . . . " [p.248]
* LATITUDE effect:
* He also predicted that the flash would be visible much longer in the
* polar regions: "Dans le pays du nord (et même près di pôle sud) où
* l'atmosphère est très lourde, le disque du soleil surgit et disparaît
* très lentement, le phénomène des couleurs du soleil à l'horizon (si
* l'atmosphère est assez pure), doit être plus long et plus marqué que
* dans les pays plus près de l'équateur." [Note, p. 250]
* Mostly about scattering, which the author calls "diffraction".
* Having (correctly) attributed the red color of the normal sunset to
* this, he then gets into the green (or blue) flash. The whole paper is
* purely qualitative argument from analogy -- the worst kind of sloppy
* thinking. "Relativement au rayon bleu, je pense pouvoir dire aujourd'hui,
* presque avec certitude, qu'il n'est engendré ni par la réfraction ni par
* la diffraction." He tries to observe the spectrum of the setting Sun, but
* it fades out on him; so he argues it can't be due to refraction, which
* would cause one color to be left at the end.
* "Pour démontrer que le phénomène du rayon vert ou bleu, etc., n'est
* pas engendré par la réfraction, on pourrait citer beaucoup d'autres
* faits, mais j'ai hâte de finir." Yeah, sure.
* "On peut donc conclure que le phénomène du rayon vert ou bleu est un
* phénomène intraoptique, et je crois qu'il tire son origine du contraste
* entre la couleur orangée ou jaune du Soleil et la couleur bleu du Ciel;
* ou encore, entre la couleur blanch de l'auréole qui entoure le Soleil et
* la couleur noirâtre du désert et de la mer." (!!!) All garbage!
* Groff's 6th paper
* This is the continuation of the long paper of the previous year.
* Mostly, it supplies examples of the uses of blue and green coloring in
* ancient art and writing to support his inferences about the sunrise
* and the green flash, so that ". . . par ces mentions, représentations et
* usages nous avons été induits à reconnaître que le phénomène naturel
* ou astronomique, le plus ancien dont on possède des attestations sur des
* monuments originaux, est le phénomène du rayon vert ou bleu."
* a novice's useless report
* Fisher #40
* DOUBLE BLUE FLASH due to MOTION OF SHIP
* (report of Captain Salveson of the Royal Norwegian Navy)
* Is this the first GF report in JBAA? (probably)
* EARLY CALCULATION SCALED TO HORIZONTAL REFRACTION (1/40)
* note change of year but not volume number
* Goodacre (1905) thought this was the first in JBAA; it is not.
* But it is almost certainly Whitmell's first paper.
* (Note a paper by the infamous "Leo Brenner" (Gopchevic) above this!)
* Fisher #146
* Comment by "M. le President" on Schmoll's observations of a deformed Sun
* This seems to be the first GF mentioned in BSAF.
* Fisher #30, O'C #196
* Ernst Wölffing's adds to Ekama's observation his own (useless)
* Fisher #162
* Mostly citations of earlier works, esp. in Eng.Mech., and Ranyard's
* "Knowledge" article (1889)
* Note change in volume number but not year: JBAA changed volumes
* between the Sept. and Oct. issues.
* GF refs. in Nature
* Observations of green *Sun* and refs.
* unidentified PLANET flash
* Fisher #83
* Mostly citations of earlier works
* O'C #153
* Arthur Mee indulges in purple prose
* Mostly references to JBAA reports; requests observations from SAF members.
* O'C #246
* relay of a GF report from J.F.Young; not useful, and confuses additive
* and subtractive color mixing (cf. his BSAF paper above)
* Note change of year but not volume number
* Fisher #163, O'C #245
* Not about green flash or "green ray" at all, but green *Sun*
* (Note a paper by the infamous "Leo Brenner" (Gopchevic) immediately above!)
* Whitmell corrects confusion between additive and subtractive color
* mixing, and provides some references
* Letter is dated 24 Jan. 1898.
* Whitmell summarizes his earlier papers
* The item is dated 5 March 1898, but the Journal is for 1897.
* Thanks to Ray Emery for supplying this!
* Seems to be an exact reprint of his 1896 paper in Bull.Inst.Egypt.
* Whitmell reports seeing the colored rims
* One of a series of "Miscellaneous" items, signed by Whitmell, p.93.
* (This seems to have appeared about mid-year, 1898.)
* Thanks to Ray Emery for supplying this!
* SUNRISE observation of GF over the Sinai (cf. Escher, 1930)
* ". . . ce fait, que le rayon vert ne se voit pas toujours , même dans
* les meilleures conditions de pureté d'atmosphère."
* Fisher #89, O'C #240
* Abstract of de Maubeuge's report to the Académie des Sciences
* This version reports "un rayon de couleur vert émeraude, qui a couvert
* un arc de 10° au-dessus de l'horizon." But the C.R. version merely
* says "Le sommet des montagnes était à environ 10° au-dessus de
* l'horizon." Probably this was a typo, and 1 degree was intended; in any
* case, the C.R. report makes this appear to be a normal flash, not a green
* ray. Cf. his 1886 letter, in which the altitude is 1° or 2°.
* O'C #239; Fisher #90
* Report of de Maubeuge's letter, in the account of "Académie des
* Sciences de Paris, 26 Septembre --- 3 Octobre 1898"
* O'C #241; Fisher #91
* Another remark on the shape that predicts the inf.-mir. flash:
* ". . . le spectacle est souvent accompagné de déformations du disque
* solaire, déformations des plus curieuses, imitant depuis la forme d'un
* ballon jusqu'à celle d'une ligne brisée."
* Fisher #72
* PIOT-BEY invokes Groff and de Maubeuge
* "Peu de contrées paraissent se prêter autant que l'Égypte à la
* manifestation du rayon vert."
* Fisher #117, O'C #106
* An account of Piot-Bey's C.R. paper
* MIS-cited by F.K., who gave the year as 1915!
* Fisher #118 has it right
* RED and VIOLET rims observed; photographs of flattened sunsets
* Drawings of typical sunset distortions
* O'C #109 -- he has the wrong date
* A report of de Maubeuge's CR paper, propagating the 10° error
* and giving his initial as K., not H.
* Hix sets off a thread with Question 536
* Brocard (below) says Hix refers to de Maubeuge's CR paper.
* AFAS = Association Française pour l'Avancement des Sciences
* Report on de Maubeuge's CR 127, 453 paper; cited by Plassmann
* This is issue Nr. 48
* Plassmann objects to de Maubeuge's explanation in Nr.48
* He cites the obvious objections: that solar protuberances would be
* seen easily at eclipses, and that the green would be transmitted far
* better high in the sky. He then suggests it might be due to selective
* atmospheric absorption, giving a very vague and arm-waving concept,
* and suggests "Fortgesetzte Spectralbeobachtungen".
* This is Nr. 51, 17.Dez. 1898 of Naturwissenschaftliche Rundschau,
* Wöchentliche Berichte über die Fortschritte auf dem Gesammtgebiete der
* Naturwissenschaften.
* An experienced observer supports the refraction explanation
* Comments on the items in Nr. 48 (de Maubeuge) and Nr. 51 (Plassmann)
* Fisher #134, not read
* Report on Libert's letter to Cornu in CR 127, 792 (1898)
* This is issue Nr. 3
* Report on Piot-Bey, Groff, and de Maubeuge
* This is issue Nr. 6
* Reply to Hix (Question 536)
* "L'explication, toute physico-physiologique, et, par conséquent, je le
* répète, purement subjective, est des plus simples."
* AFAS = Association Française pour l'Avancement des Sciences
* Reply to Hix (Question 536), citing Piot-Bey and Groff
* "De ses observations M. Piot-Bey conclut que le rayon vert est un
* phénomène absolument objectif." [ A nice juxtaposition! ]
* AFAS = Association Française pour l'Avancement des Sciences
* Reply to Hix (Question 536), naming (but not citing) Cornu.
* AFAS = Association Française pour l'Avancement des Sciences
* Reply to Hix (Question 536)
* A curious explanation: at sea, he will have the waves be the prism; but
* on land. "l'effet de prisme y est formé par la couche atmosphérique
* ondulée, plus dense, qui avoisine le sol . . . ."
* Perhaps we could regard this as a precursor to Fraser's INVERSION-WAVE
* suggestion?
* AFAS = Association Française pour l'Avancement des Sciences
* Final reply to Hix (Question 536)
* This remarkable letter terminated the discussion; and no wonder:
* it contains a remarkably complete bibliography.
* Brocard cites all of Groff's papers in Bull.Inst.Égypt,
* 14 references in all.
* AFAS = Association Française pour l'Avancement des Sciences
* Another reference to de Maubeuge giving his initial as K., not H.
* This is mainly about the reports of Plassmann and Schülke, however.
* Probably this is the note cited in Prometheus 14, 48 (1903), though
* the page number given there is 425.
* Note that volumes overlap years!
* 29 March, No.494
* reviews of the works of Piot-Bey, Groff and de Maubeuge
* Guébhard's talk at the 21 Avril 1899 Séance de la Soc.Fr.de Physique
* Guébhard mis-cites "Trèves" in C.R. 101, 845, as well as citing
* Dr. Abbate Pacha, Groff, and Daressy. He seems never to have seen
* a GF. His paper is contested by Pellat (see below), who cites his own
* observations in 1887. Then Guébhard cites Franceschi back at him.
* These discussions were reviewed in Ciel et Terre later in 1899
* (see below).
* Note that these are in the section "Résumés des Communications"
* where the page numbers bear a superscripted asterisk, not the
* full-length papers printed with simple page numbers.
* [This volume contains papers by the Curies and by Becquerel on radium;
* papers by Cornu on optics, by Amagat on the equation of state; by
* Poincaré and by Deslandres; by Pellin and Broca on their
* constant-deviation spectrometer; etc.! What a wonderful time this
* must have been to be a French physicist!]
* Pellat refutes Guébhard
* "M.Pellat, tout en reconnaissant que le phénomène des couleurs
* consécutives peut jouer un rôle dans la vision du rayon vert,
* considère le rayon vert comme ayant une existence réelle."
* He then cites his own 1887 paper and observations.
* Raveau's GREEN RAY BELOW the horizon
* "M.Raveau a observé un phénomène très différent de celui que
* décrit M. Pellat. Au moment où le bord supérieur du soleil venait de
* disparaître, il a vu la mer s'éclairer, pendant un temps très court,
* d'une lueur verte; cette lueur a occupé d'abord un petit triangle, ayant
* sa base sur l'horizon, à l'endroit où s'était évanouie la petite ligne
* lumineuse qui constituait la dernière partie visible du disque du soleil.
* La région éclairée s'est graduellement resserrée vers l'horizon et a
* disparu, l'ensemble du phénomène ressemblant à l'écoulement rapide
* d'un liquide lumineux."
* long, sensible account; RED FLASH DISCOVERED
* ". . . nombreuses observations que j'en ai faites."
* "J'avais . . . été frappé par ce phénomène réputé extrèmement rare
* (si l'on en croit la romanesque idylle de Jules Verne) . . . ."
* "Piqué au vif, par ces observations fréquentes et faciles . . . j'ai
* exploré avec un assez fort groissement, l'extrême bord apparent de
* l'astre radieux et j'ai eu la satisfaction de constater, au moment
* où le point opposé du limbe du Soleil quitte la Terre, un
* rayon rouge fort vif ."
* "Avec une lunette, il est facile de constater le rayon rouge et orange
* du dessous du limbe solaire, lorsque celui-ci prend contact, ou bien
* perd contact (au lever) avec l'horizon."
* "Le rayon vert est un simple phénomène de réfraction et il doit se
* produire aussi bien pour la Lune et pour les étoiles que pour le Soleil,
* aussi bien au lever qu'au coucher d'un astre suffisamment brillant, et
* le rayon rouge pourra être observé, avec certaines précautions; ces
* deux rayons complémentaires sont observables en montagne, aussi bien
* qu'en plaine et qu'en mer; . . . ."
* (Unfortunately, he then tries to connect the red ray with the color of
* lunar eclipses.)
* This is almost identical to Turquan's note in Revue Scientifique (4),
* Vol. 11:1, No. 4, pp. 122-123 (28 Jan. 1899), which evidently appeared
* before the BSAF version.
* Fisher #143, O'C #143
* Useless nonsense; contrast colors
* O'C #85
* Wordy description of mock-mirage flashes. He seems to think some of
* this has to do with the Sun's atmosphere. Nice use of colored filters to
* bring out the red and green limbs.
* Early mention of WAVELENGTH DEPENDENCE of LIMB DARKENING: he knows the
* limb is redder than the center. He also invokes atmospheric dispersion,
* but apparently is flummoxed by the mock mirages.; vague references to
* the "black drop" at Venus transits, and atmospheric scattering.
* J.J.Taudin Chabot writes German as if it were French.
* See corrections of typos here in Met.Z.16,p.523. (Fisher #19)
* See corrections of typos here in his 1900 paper, Met.Z.17,p.335.
* Fisher #18
* LORD KELVIN's incredible estimate
* ". . . in an instant I saw a blue light . . . which, in less than the
* one-twentieth of a second became dazzlingly white . . . ."
* See further discussion in 1910 !!
* This is in the 31 August issue.
* An Erratum appeared in the 1 Sept. issue, saying that 5 o'clock should be
* 4 o'clock, and that "of sunrise" should be added after "light" in line 7.
* Fisher #64, O'C #69
* Report on Kelvin's letter to Nature
* This is issue Nr. 40
* (This is a report of the discussion at a meeting of the French
* physical society, involving Guébhard, H. Pellat, and Raveau.)
* "Guébhart" is Paul Émile Adrien Guébhard, who had recently
* published several papers on vision, and as a medical man was
* predisposed to a physiological theory of green flashes.
* Guébhart's "bibliographie complète dans un mémoire
* présenté à la Société française de physique" is probably no
* more than the references cited in the "Séances" (1899).
* Is Raveau's observation that "la mer s'éclairer, pendant un temps
* très court, d'une lueur verte" a green fog below eye level?
* Seems to be a summary of Groff's work; all derivative, anyway (no refs.)
* EARLIEST VENUS GREEN FLASH?
* passengers on board the "Saint-Laurent"
* part of O'C. #303
* passengers on board the "Saint-Laurent"
* Note discrepancy in 5th passenger's name.
* 31 Mars issue
* Fisher #176
* part of O'C. #303
* translated from the Revue Scientifique account
* part of O'C. #303
* Jules Garnier refers both to the St.Laurent report and his own in 1899
* This time he omits mentioning the waves; only atmospheric refraction
* forms "un spectre . . . devant l'oeil de l'observateur, lequel ne retient
* des sept couleurs de ce spectre que le vert, qui est la couleur la plus
* intense . . . ." [Seems to be the first to claim that green is seen
* because it is "brightest" to the eye!]
* 21 Avril issue
* H.H.Turner sees a GF at the May 23 eclipse in Algiers -- see item on p.300
* J.J.Taudin Chabot, thinking the "green radiation" has something to do
* with the Sun or Moon, observes a partial solar eclipse without result.
* Footnote corrects his earlier paper in Met.Z.(1899)
* Fisher #20
* cites his earlier paper in Met.Z.(1899)
* As the Sun followed the slope of a mountain, "blieb dieses Mal eine
* grün leuchtende Stelle nahezu 30 Sekunden lang sichtbar"
* O'C #191; Fisher #21
* abstract of the 7 passengers' account in Revue Scientifique
* Fisher #177
* part of O'C. #303
* not useful
* Col. E. E. Markwick, F.R.A.S.
* Fisher #84
* Not a very useful observation; only a couple of sentences on p.5
* This is the lead article in Vol. 1, No. 1 of "Das Weltall"
* WHITMELL's first land-horizon flash (2nd GF)
* "Green Flash is a more suitable name than Green Ray."
* Fisher #147
* The same item, cut down slightly, and citing his vol. 5 note.
* reference to previous year's Intermediaire de l'Assoc.fr. pour
* l'avancement des sciences
* JANSSEN reports Hansky's GF on Mont Blanc, and adds his own
* Aleksey Pavlovitch Hansky was an assistant at Pulkovo who spent
* some time at the Meudon Observatory. He specialized in photographing
* the solar surface, and monitoring its activity. He seems to have been
* the first person to notice the relation between the shape of the corona
* and the sunspot cycle.
* Hansky is quoted as describing a morning flash, with the textbook
* explanation; but modified: ". . . s'il existe beaucoup de vapeur d'eau,
* il ne reste du spectra que le partie rouge et une faible bande dans le
* vert ; mais, si l'air est très sec, la partie verte du spectre est
* intense et c'est elle que nous voyons au premier moment de l'apparition
* du Soleil, quand le spectre passe devant l'œil de l'observateur."
* To this, Janssen adds: "Cette explication est exacte, mais il faut
* remarquer que c'est encore plus l'absence de brumes que de vapeur qui
* importe à la production du phénomène, car j'ai vu très nettement le
* Rayon vert dans le Pacifique."
* (Presumably this was during his 1883 trip to the Carolines -- too late
* to have influenced Jules Verne.)
* At the end of this volume are several scientific notes in sections
* denoted by capital letters; this is section F. The Hansky quotation
* is on pp. F.7 and F.8. The index is section I.
* Reprinted in Janssen's works, Vol. 2, pp. 544-550 (see pp. 548-549)
* in 1930. A slightly edited extract from Hansky's account was also
* reprinted in 1907 by Radau (q.v.).
* Available at Gallica. The volume is a sort of combination of the
* Rubber Bible and the Nautical Almanac, with the World Almanac thrown
* in: there are the tables of weights and measures (and currencies) of
* various countries; conversions among the Julian, Gregorian, Moslem and
* French Revolutionary calendars, as well as a variety of physical and
* chemical tables.
* a badly confused account; thinks "actinic" rays change the response of
* the eye?
* O'C #74
* PRIORITY DISPUTE; no GF info
* J.J.Taudin Chabot has a priority fight with T.J.J.See over the use of
* colored glasses:
* ". . . erlaube ich mir die Anfrage, ob sie durch eine redaktionelle Notiz
* auf meine Priorität gegenüber Professor Thomas J. J. Se [sic], U.S.Naval
* Observatory, Washington, in Sache der Einschaltung selektiv absorbirender
* Medien zur Verdeutlichung der Beobachtung am Fernrohr hinweisen wollten."
* (and cites his paper in Met.Z.16,425(Sept.1899).)
* In fact, both were scooped by Stampfer (1851).
* J.J.Taudin Chabot uses his filter method to examine colored rims, and
* finds that a smoke plume 450m away does *not* have colored edges.
* He seems not to be a "morning" person:
* "Der häufigen Beobachtung des `Sonnenaufgangs' . . . stellen sich
* Schwierigkeiten verschiedener Art in den Weg, deren nicht geringste,
* vielleicht indessen nur individuellen Charakters die ist, dass zu jener
* im Allgemeinen ziemlich frühen Tagesstunde die persönliche Schärfe
* des Wahrnehmungsvermögens sich nicht immer schon in vollem Umfange
* eingestellt hat . . . ."
* O'C #192; Fisher #22
* EARLY CALCULATION SCALED TO HORIZONTAL REFRACTION (1/200 = 10" = 2/3 s)
* Anomalous dispersion proposed: cf. the Julius file (far below).
* ". . . the physicist of the Committee, Dr. W.H.Julius, of Utrecht. . . "
* (from Nijland's account of the Expedition to Sumatra, Amsterdam, 1903)
* (Nijland was the Sec.-Treas. of the Eclips-Commissie; part of his report
* is on the Web at http://www.exploratorium.edu/eclipse/1901.html .)
* Julius proposed anomalous dispersion as the explanation of everything
* in sight: the solar limb, prominences, sunspots, stellar spectra. . . .
* (see J. Hartmann, A.N.175, Nr.4197, 341-368 (1907) for refutations.)
* Fisher #61 indicates this volume is in series 2.
* O'C #64 agrees
* not useful
* Fisher #6
* not useful; only half a sentence is devoted to GF
* The page number is mis-printed without the "2", explaining the wrong
* reference to p.56 given by O'Connell, who also mis-copied the name.
* Why did he bother with such trivia and yet reject (as he says) 200
* references?
* O'C #282
* John Franklin-Adams sees a GF like Baily's beads [WAVES!]
* ". . . the phenomenon here described may have been caused by the waves of
* the sea taking the place of the mountains of the Moon. The evening was
* calm, and the waves not large enough to make this possible unless images
* of the waves were thrown up by a mirage state of the atmosphere. I have
* twice seen from a steamer's deck mirage images of the sea waves, about
* a mile distant, thrown up sufficiently to entirely hide the horizon."
* N.B.: We often see such an effect here; I have several pictures of it.
* cf. Evans, 1914.
* This is the May 1901 paper mentioned in Admiral Maclear's 1906 letters.
* Caution: M.N. volumes do not coincide with years here (Nov.1901).
* Fisher #1
* JBAA abstracts the above
* This appears to be a reprint of J.F.-A.'s note in M.N.
* No.1892, June 28, 1901
* "F.R.A.S." comments on Franklin-Adams's observation;
* he is troubled by the "Baily's beads" allusion, taking it literally.
* Note that the heading is a sub-head within a long letter of many parts
* that begins on p.424; the main title is "Greenwich Observations".
* No.1892, June 28, 1901
* The "BILIOUSNESS" tale:
* Only the last sixth of this letter deals with the notorious GF story:
* The full heading is:
* "Sunspots and terrestrial magnetism; To ``F.R.A.S.'' -- the green flash
* a sign of biliousness"
* "I was much interested in ``F.R.A.S.'s'' observations on the ``Green
* Flash.'' I have repeatedly seen this very curious phenomena [sic] ;
* but really, I have never taken any notice of it, and it is the first time
* I have observed it mentioned in print. I remember it struck me most
* vividly when I was staying at Torquay, and I communicated my ideas to a
* medical friend, who promptly said I was suffering from biliousness, and
* there and then prescribed. I remember I looked again for it the day after
* I had taken some medicine, and my friends saying that I should not see it
* again -- at all events for some time to come -- came true, and I had
* forgotten all about it until I saw the remarks of your valuable
* correspondent."
* No.1893, July 5, 1901
* O'C #71
* Langford [44949] identifies "Treadle" as C. Mostyn, from his letter in
* Nature 44,352(1891). Cf. similar remarks in his 1906 Knowledge paper.
* I regard this identification as secure.
* EXPERIENCED: "Having been much at sea in former years, I have had many
* opportunities of observing this very beautiful and interesting
* phenomenon. . . . many scores of observations . . . ."
* EARLY RECOGNITION of the Type A sunset and mirage effects:
* "I have noticed that a particular form of refraction was most favourable
* to its appearance. When the sun, on approaching the horizon, assumed
* curious shapes as of a goldfish-globe or a pear, then there would nearly
* always be a green or bluish flash at the moment of disappearance. On the
* other hand, when the sun assumed the shape of an oval with major axis
* horizontal, the flash did not appear."
* He correctly diagnoses Franklin-Adams's "beads": "I fancy they must be
* caused by ripples on the sea-surface at the horizon. . . ."
* His triple flash was seen from "the old Macquarie , now a training-ship
* for officers under Lord Brassey's scheme."
* Edward Gilbert finds that this trip from London to Sydney was from
* October 28, 1890 to January 29, 1891, and that the ship was built in
* 1875 as the Melbourne ; renamed Macquarie in 1888, and renamed again
* to Fortuna in 1904, before being broken up in 1953. Gilbert also says
* that the pseudonym "Treadle" was taken from Mostyn's interest in treadle
* bicycles.
* No.1893, July 5, 1901
* Fisher #104
* Completely irrelevant remarks that have nothing to do with green
* flashes, as Langford [44949] soon makes clear.
* No.1893, July 5, 1901
* The citation of letter 44819 of "T.R." actually means 44919 of "F.R."
* -- an example of the numerous typos in the E.M.'s letter columns.
* "But to some eyes it was red , not green."
* No.1894, July 12, 1901
* Langford identifies "Treadle" as Mostyn, and implicitly chastises "F.R.".
* He succinctly summarizes the subject in 1 paragraph!
* No.1894, July 12, 1901
* Whitmell's 1-sentence announcement of a cloud-top flash
* No.1902, Sept. 6, 1901
* Fisher #150
* Whitmell's full report of the above observation
* Evidence of VISUAL ADAPTATION:
* "I also noticed that, before sunset, the decreasing segment of the
* setting Solar disc, originally yellow, became gradually whiter in tint.
* Mr. Scriven Bolton, who was with me, also observed the flash. We both
* used opera-glasses."
* (This seems to be vol. 9, 1901).
* Thanks to Ray Emery for supplying this!
* PICKERING's original GF note, "confirming" Franklin-Adams's observation
* -- but without the beads!
* Cited as a "minor publication" in HCO's Annual Report for 1901/02, p.15
* Caution: M.N. volumes do not coincide with years here (Nov.1901).
* Fisher #113
* JBAA abstracts the above
* Naturwiss.Rundschau abstracts Pickering's report
* Nr. 50
* Fisher #115
* PICKERING's "optical illusion" paper
* Caution: M.N. volumes do not coincide with years here (Nov.1901).
* "The effect, I presume, is subjective, and merely a case of
* complementary colours . . . . The fact that my assistant could not see it at
* sunrise . . . confirms this view."
* Fisher #116, O'C #105
* This is the NIJLAND paper that prompted HAVINGA to observe!
* EXCELLENT ADVICE to amateur observers!
* ". . . Prof. W.H.Julius and J.H.Wilterdink, and me, members of the Dutch
* expedition to observe the total solar eclipse of 18 May near Padang . . . "
* Early use of the term "GREEN SEGMENT" (it was first used by Winstanley):
* "This green segment , that I have observed more, though not so
* brilliant, is badly conveyed by the name ``flamelet''."
* ALBERT ANTONIE NIJLAND
* 530 nm given twice
* double flash observed "Durch die Bewegung des Schiffes". (WAVES)
* (For the benefit of people unfamiliar with Astronomische Nachrichten ,
* I should point out that its columns are numbered, rather than pages.)
* Fisher #107
* JBAA abstracts the above
* DISPERSION proposed (!) -- red and green rims seen
* Abstracted in JBAA 12, 299 (1902), which also mentions Hills (next).
* (I file the JBAA summary after Hills, some months too early.)
* See his obit. in M.N. 81, 245 (1921), which mentions his GF observations.
* He was VP of the RMS in 1918 and 1919.
* Fisher #4
* BLUE and VIOLET seen after green with 12x binocular
* ". . . the narrowing segment . . . is first seen to turn green at its two
* extremities; the green colour then appears to run inwards until the whole
* area of the segment appears coloured. . . . after . . . about a second the
* green fades away and is momentarily replaced by a blue or blue-violet.
* The latter is immeasurably more feeble than the green . . . ."
* Major E.H.Hills, R.E.
* Fisher #57, O'C #51
* Schmidt discusses Julius's chromospheric and GF theories, both based on
* anomalous dispersion. It seems the English word "FLASH" has led to this
* confusion (cf. "flash spectrum"). Schmidt compares Julius's theories to
* his own for the solar atmosphere, involving critical refraction --
* essentially, an early example of Hasse's ``Kimmfläche''. Schmidt doesn't
* accept Julius's chromospheric model, but seems favorably inclined toward
* his GF theory.
* cf. the shorter version in Met.Z. 19, 337 later in the year (below)
* Fisher #131
* Ricco quotes from, and comments on, Prinz:
* He seems to draw no distinction between the green rim and "punto verde".
* the 2 photos reproduced show flattening, not distortion
* WARNING: the nutty librarians seem to catalog this journal as
* "Società Astronomica Italiana. Memorie" -- though nothing of
* the sort appears in the published volumes! (That's because the Italian
* Astronomical Society took it over later.)
* O'C #118
* Belated account of Pickering's *first* paper in M.N.
* Fisher #114
* JULIUS republishes his SCALED REFRACTION calculation
* (This appears to be an exact reprint of the 1901 paper)
* NOTE: this appears to be Julius's last GF publication.
* O'C #65; Fisher #63
* Keatley Moore replies to Query No. 69
* and refers to Col. Markwick (see above, 1900)
* He believes it is an afterimage: "The ghosts persist with me about 2
* seconds, which is also the time the green flash lasted."
* Incorrectly cited by Mulder (1922), whose error was copied by
* Feenstra Kuiper (1926). Fisher has it right.
* Fisher #102
* Keatley Moore receives Whitmell's response (below)
* Whitmell counters Moore with earlier references
* Fisher #148
* HUGH ROBERT MILL's first GF report: green, blue, violet
* ". . . there was only one night on which the sunset was sufficiently clear
* to show the interesting phenomenon of the green ray. This was on Sunday,
* August 11, when, as the upper edge of the sun touched the sea-horizon, a
* beam of yellow light, almost instantaneously passing through green to blue
* and dying away in violet, was distinctly visible. It is remarkable that
* so few observers have noticed this striking appearance, which must [sic]
* be visible every time the unclouded sun dips beneath a sharp horizon."
* (pp. 418/419) -- so he evidently believed the "textbook" story.
* This was the Antarctic expedition organized by the Royal Geographical
* Society in 1901 and led by Robert Falcon Scott. Mill notes on p. 422
* that "Lieut. E. H. Shackleton undertook the salinity determinations, and
* proved a very apt and enthusiastic pupil" -- a prophetic remark that
* reminds me of Picard's remark (1680) about Römer.
* A nice halftone photo of this sailing ship is on p. 421.
* RED FLASH discovery? [No; it appears Turquan (1899) beat him to it.]
* "It occurred to me some time ago that, under suitable conditions, there
* might be seen at sunrise and at sunset not only a green flash but also a
* red flash. . . ."
* "In the belfry of the Wesleyan Chapel, on the west side of Woodhouse
* Moor, there are narrow horizontal openings, through which, at certain
* times, the setting sun can send his rays to an observer at the large
* band stand, about 300 yards away.
* "On Saturday, 26th April, between 7 1/4 and 7 1/2 p.m., I was so
* exceptionally fortunate as to observe through the openings no fewer
* than three green and three red flashes."
* (Monday, 28th April, 1902; col. 4.)
* Reprint of the above item, with minor differences in editing:
* "In the belfry of the Wesleyan Chapel, there are narrow horizontal
* openings, through which, at certain times, the setting sun can send
* his rays to an observer at the large Band stand, about 300 yards away."
* An account of Whitmell's talk appears in Obs. 25, 226 (1902).
* Fisher #149, O'C #296
* The original manuscript of the above, printed in full, it appears. The
* JBAA version is improved by editing. But this version has appended the
* text of Prof. E. E. BARNARD's letter from Mt. Hamilton, in addition to
* an observation of a red flash due to cloud, as suggested by Whitmell.
* Barnard, in his letter, says "I have seen the phenomenon (at sunset),
* many, many times in the past fifteen years." (But, clearly, never at
* sunrise.)
* Whitmell answers Query No.72, adding further evidence
* summary of Backhouse's M.N. paper in March
* A summary of W. H. Pickering's M.N. report
* This is the item mentioned by Katherine Bracher in 1992. It mentions
* Kelvin's observation "three years ago", and that "Professor Nijland, of
* Utrecht, Holland, has lately seen it several times at sea." As it says
* that ". . . Pickering calls attention . . . to what he names the `green flash'
* at sunset", one can see how the notion arose that WHP had named it.
* "Observations may be made with the naked eye, though a small telescope
* or opera-glasses will be found advantageous."
* reprinted from A.N., with typos & other editorial changes added!
* Juli 1902 issue
* Fisher #108, O'C #255
* a series of GF papers followed Nijland's:
* First, a simple visual observation of a few sec. duration.
* "Frau Marie Jautz aus Wien in St. Andra" bei Triest" sees a classic
* inf.-mir. flash:
* ". . . verwandelte sich der noch sichbare Rest derselben in ein flaches,
* grünes Scheibchen, welches auf der Meeresoberfläche zu schwimmen
* schien." [nice observation of the mirage!]
* Fisher #175 ?
* J.J.Taudin Chabot's attempt to observe a GF at a partially-eclipsed
* sunrise was clouded out.
* Fisher #23
* Condensed version of Schmidt's Deutsche Revue paper in April (above)
* Only the first half of Schmidt's D.R. paper is quoted here; the part
* comparing his solar theory with Julius's is omitted.
* Fisher #132
* Alexander Herschel's GF over cumuli (see footnote, p.294)
* Cites Hopkins (1883) and Swan.
* July 24 issue
* Fisher #56
* BOILING associated with an inferior-mirage flash
* O'C #293
* Brief review, citing Biot's text, Krifka/Sterneck, and Arctowski
* (Properly belongs in the "distorted sunsets" file; but kept here, as it
* elicited the following GF observations)
* (#1525, 16 Août 1902)
* Seems to be a GREEN FOG observation
* ". . . tout à fait à l'horizon même, l'épais rideau de nuages noirs et
* pluvieux ainsi que le fond éloingé du paysage prirent une teinte
* verdâtre bien prononcée pendant quelques instants seulement,
* comme s'ils eussent été éclairés par la lumière électrique."
* (#1530, 20 Sept. 1902)
* Whitmell corrects "H.P.", and argues TERMINOLOGY:
* "The term ``green ray'' is a bad one. ``Green flash'' is much better.
* . . . There is nothing like a ``ray.''"
* "On August 24 I witnessed three green flashes in succession, as the
* sun's tip sank behind two strips of clouds and the horizon."
* No.1957, Sept. 26, 1902
* "Sigma" corrects "H.P." in a strange way
* "What ``H.P.'' describes is not the green ray, but only a dispersion
* effect among the clouds."
* Eric Hutton has identified "Sigma" (Mr Sprague) [ref. No. 3105 p326]
* No.1957, Sept. 26, 1902
* FRAS corrects "H.P"'s crepuscular-ray observation (query 285, p.135)
* One paragraph headed "The Green Ray" in a much longer letter
* No.1958, Oct. 3, 1902
* Whitmell takes "Sigma" to task:
* "The letter by ``Sigma'' (p.154) affords an excellent illustration of
* the danger of a writer dealing with a subject about which he is ignorant."
* No.1958, Oct. 3, 1902
* Refers to Prinz's paper (1898) and Riccò's work
* (#1533, 11 Oct. 1902)
* long observations of "green ray" [probably visual illusion; see below]
* "Le 13 mars 1899, il a duré 112 secondes 1/2, et le 14 mars 1899, 364
* secondes. A cette dernière date, beaucoup de personnes ont été
* frappées de la coloration verte si prolongée. Le 23 mars de cette
* année, j'ai encore revu le phénomène pendant 107 secondes.
* . . . Dans l'ordre de décomposition apparaìt d'abord le rouge, puis
* l'orangé et le jaune et enfin le vert."
* cf. Cornsweet et al. in VISION file for probable explanation (BLEACHING).
* (#1535, 25 Oct. 1902)
* Fisher #71, O'C #80
* ADAPTATION?
* ". . . the flash was very distinct, but seemed to my vision to be such a pale
* green as to be almost white."
* No.1965, Nov. 21, 1902
* Fisher #96
* a 3-sentence abstract of Libert's La Nature 30:2, 332 (1902) paper,
* calling him "Lucian" (instead of Lucien) Libert;
* also mentions the original report in No.1525, (wrong) p. 161 (copied
* from Libert)
* also mentions Garcin's paper on p. 161 in Aug. 1902 (not naming Garcin).
* Dez. issue
* WHITE, then GREEN FLASH -- evidence for ADAPTATION
* "Da ich den Sonnenuntergang mit Rücksicht auf das eventuell auftretende
* Phänomen erwartete . . . ."
* Clearly an inf.-mir. flash: ". . . den ganzen Tag über herrschte leichte
* Bora . . . ."
* Fisher #45
* a 3rd-hand account of the GF and Julius's theory, attributed to Met.Z.
* sounds like a useless novice report, but might be a real GREEN RAY?
* "Au moment précis où le disque solaire s'effeçait derrière la ligne
* des eaux, instantanément éclata à l'horizon un foyer d'un
* vert émeraude intense projetant dans tous les directions des rayons
* qui se détachaient sur une atmosphére émeraude très clair. Notre
* correspondant insiste sur la beauté féerique de ce phénomène
* absolument remarquable."
* Nice summary of how the inf.-mir. "segment" becomes green from the ends
* and is followed by blue and violet (nameless observer using binoculars)
* Knight again, observing in Italy
* "I am inclined to believe that a change in latitude affects its colour
* to a certain extent. Such is my opinion from thirty-three observations
* made in Italy since Aug. 17 to [Sept. 25]."
* GF mentioned only in short 2nd paragraph of longer letter.
* No. 2011, Oct. 9, 1903
* Fisher #66
* Clapham is uninformative
* ". . . observed on several occasions, and always found it best to be seen
* on a clear sea horizon."
* No. 2013, Oct. 23, 1903
* Chabot seems confused -- useless
* O'C #14 -- why did he bother with this? There are mentions of
* green and red rims, and the use of copper- and cobalt-glass filters.
* But Chabot's earlier papers are more interesting.
* MOUNTAIN sunset GF from 2565m
* Fisher #36
* The interview with Jules Verne that was excerpted in "T.P.'s Weekly",
* in which Verne cannot recall the name of his novel, and has to be
* reminded of it by his wife: "'. . . a visit to Fingal's Cave . . . was the
* origin of my book, "The -- the --"' M. Verne paused. 'I really forget
* the name,' said he. 'Do you remember it?' he asked, turning to his wife.
* '"The Green Ray," was it not,' suggested Madame Verne.
* 'Oh yes, that was it, of course -- "The Green Ray." One must be
* excused,' added he, laughing, 'if, among so many titles the right one
* is not for the moment forthcoming.'"
* The interviewer was Gordon Jones.
* Available at HathiTrust:
* https://babel.hathitrust.org/cgi/pt?id=uc1.b3042632&view=1up&seq=676
* and at Google Books.
* June, 1904 issue of this monthly.
* BEGIN T.P.'s WEEKLY series
* As these items are mostly in the "T.P.'s Letter Box" section, and
* unsigned except for initials or pseudonyms, they are a bit difficult to
* give in standard bibliographical form. This magazine lacked the useful
* identifying numbers of English Mechanic, too.
*
* This is the item that started it off, merely by mentioning Verne's
* book:
* No GF, but an interview with Verne from "the current number of 'Temple Bar'"
* is quoted in which he mentions "Le Rayon Vert" -- as well as H.G.Wells.
* Some of these early issues are now (2019) available at the HathiTrust
* website:
* https://catalog.hathitrust.org/Record/000503105
*
* as well as at Google Books. From the information in their catalog,
* one learns that "T.P." was Thomas Power O'Connor (1848-1929).
*
* Note: Part II of Joseph Conrad's "Nostromo" begins on the facing page!
* No. 83, June 10, 1904
* A novice relates 2 sightings, with no useful details, and asks for an
* explanation: "I am curious to know whether it is only seen when the sun
* is setting over the sea."
* June 24, 1904
* Whitmell stirs up enthusiasm again, noticing the YELLOW stage:
* Another Southport flash!
* "The disc of the setting sun was decidedly orange. As it sunk below
* the horizon, the diminishing segment paled to yellow, the colour
* changing to a beautiful green when only the tip of the sun was left."
* No.2052, July 22, 1904
* Fisher #151
* Responses to Whitmell begin here:
* "Phusis" fails because of his "low-lying hill horizon"
* "I have looked for this phenomenon rather vainly for a long time. Is it
* necessary that the horizon should be a sea level?"
* (The similarity to "S.W."'s question in TPW is remarkable.)
* No.2053, July 29, 1904
* Whittle criticises "the crude idea that the sea water is the cause of
* the green ray, as if it were possible for light to pass through at such an
* angle."
* No.2053, July 29, 1904
* "I examined it with a binocular, and distinctly saw the feather wisp as
* described by Mr. Whitmell at the final disappearance of the sun's limb."
* No.2053, July 29, 1904
* We now interleave the letters to E.M. and T.P. in chronological order:
* Responses to "S.W." begin here:
* Another novice responds with the "Pears' Soap ad" theory, with a good
* description of the ad itself.
* July 29, 1904
* Cope reports an INFERIOR-MIRAGE flash over LAND horizon
* "Through a field-glass the last visible part of the sun appeared to
* assume an oval shape, with its longest axis horizontal, and at the same
* time the two ends became of a beautiful green colour, which extended
* towards the centre . . . ."
* No.2055, Aug. 12, 1904
* Fisher #29
* A more experienced observer refutes the "Pears' Soap ad" theory.
* ". . . several of us tested it, but with negative results. We looked
* fixedly at the red sun, and then looked quickly up at a white cloud, with
* the result that some saw a green image of the sun; but that is entirely
* different from the ``green flash,'' which is horizontal and very little
* more than momentary, whereas the visual impression of the sun on the cloud
* (and in Pears' experiment) lasts for some time."
* Aug. 26, 1904
* FIRST CLASSIFICATION?
* This issue has 3 replies. The first is a SPLENDIDLY CLEAR account of the
* difference between green flashes and GREEN RAYs:
* "In the course of sixteen years sailing the seven seas I have very
* frequently seen the green flash and also the green ray. Fine weather and
* an absolutely clear horizon are, or course, essential, but this form of
* refracted light requires other atmospheric conditions, which have not yet
* been scientifically explained, and the flash may be often looked for in
* vain when the conditions seem to be most favourable. The flash appears
* like a magnificent emerald the moment the sun sinks -- sometimes vanishes
* instantly and sometimes fades in three or four seconds. Occasionally, in
* the latter case, a luminous green ray springs from the flash and shoots
* vertically upwards to a height of about five of the sun's apparent
* diameters. Strangely enough, this phenomenon is not commonly known among
* British seamen, although it has been described for many years in a
* standard French Naval Instruction Book as a sure sign of continued fine
* weather." [cf. Trève (1885) and Wegener (1926).]
* Sept. 9, 1904
* Confusion between "green Sun" and green flash; ignore
* Sept. 9, 1904
* A beginner notices the HEIGHT effect:
* "Although both of us gave our undivided attention, there was no green
* ray visible. At the same time, however, two other friends at a distance
* of several hundred yards from us, and on slightly lower ground, declare
* they witnessed the phenomenon."
* [This is evidently the paper "Phusis" (E.M., Oct.14) had in mind.]
* Sept. 9, 1904
* a fuzzy-minded promoter of "color is entirely subjective" nonsense.
* Sept. 16, 1904
* Another refutation of "Pears' Soap"
* "I know the ``Pears' Soap'' effect well, and have seen green suns often,
* but this flash could have nothing of the same character. . . ."
* Sept. 16, 1904
* "Phusis" cites a troubling argument (evidence for ADAPTATION):
* ". . . the theory has been advanced that it is an optical illusion. How
* in else manner can any of our readers account for its visibility to some
* and its invisibility to other observers at the same time? In other words,
* is the colour flash produced by dispersion, or is it a complementary
* colour effect? If it is the former, then it should be visible to all."
* No.2061, Sept.23, 1904
* Another after-imager.
* Sept. 23, 1904
* "C.B.S." quotes an irrelevant passage from Longfellow; ignore.
* Sept. 23, 1904
* Good explanation of the standard textbook story
* "`Phusis' . . . seems to doubt whether the phenomenon known as the `green
* flash' is anything more than an optical illusion due to a complementary
* colour effect (query, complementary to what?)"
* No.2062, Sept.30, 1904
* Whitmell recommends a telescope, and mentions RED flash:
* "I have seen it once or twice, and believe I am the first to draw
* attention to it."
* No.2062, Sept.30, 1904
* "Treadle" (Mostyn) relates a beautiful sunrise flash, and adds:
* "It is never seen unless a great deal of refraction is about, as is
* evidenced by the sun assuming curious shapes --- a goldfish globe, &c."
* A clue to his identity: of the "Bedford Level Experiment," he says
* "I was concerned in it."
* No.2062, Sept.30, 1904
* Fisher #105
* Another ignoramus pushes after-images; ignore.
* "Though not having seen the green flash personally, . . . ."
* Sept. 30, 1904
* SUPERIOR MIRAGES with SUNSET drawings
* "FOG" in blank strips; GF in "cap"
* Fisher #128, O'C #272
* GREEN SUN distinguished from green flash
* "J'ai à plusiers reprises observé le rayon vert, mais le soleil vert
* en différait par sa longue durée d'abord, par la situation du soleil
* au-dessus de l'horizon ensuite, et c'est à ce titre que j'ai voulu le
* signaler."
* letter to editor from a first-time observer who claims a green flash;
* but the description clearly shows that this was only a crepuscular ray.
* An example of CONFUSION due to inappropriate TERMINOLOGY.
* "Phusis" points out some visual effects (evidence of ADAPTATION)
* "Two persons watching the sun at the same time : one sees the flash and
* the other does not, although both are careful observers."
* (attributed to T.P.'s Weekly, Sept.30, p.444 and "previous issues for
* the past few weeks.") Cf. "T.D.", Sept.9, in TPW.
* No.2064, Oct.14, 1904
* More after-imagery; though "If fatigued by a red light and then exposed
* to a yellowish light, the yellow will appear green."
* Oct. 14, 1904
* Whitmell cites some earlier works ("Phusis", Kelvin)
* No.2065, Oct.21, 1904
* Mostyn ("Treadle") counters "Phusis"
* "When I was at sea, the officers of the watch had orders to send and call
* me. . . " makes it sound as if he was the captain; but Edward Gilbert finds
* that Mostyn was only a passenger.
* No.2065, Oct.21, 1904
* This might be Rambaut? There is a reference to Froude's "Leaves from a
* South African Journal" without details; see Froude (1877).
* ". . . take care not to fatigue the eyes by staring at the setting sun. A
* wise plan is to turn the back to the sun, turning round from time to time
* for a brief glimpse, to make sure that it has not disappeared, and only
* fixing the eyes upon it finally when nothing remains visible but the upper
* edge of the disc. Unless the horizon is distant and low, the watch may be
* in vain."
* Oct. 21, 1904
* Whitmell gives several references, and confirms that "Treadle" is Mostyn
* No.2066, Oct.28, 1904
* Clearly this is Charles Mostyn, finishing the TPW series.
* "I have seen it dozens, nay, scores, of times at sunrise at sea. The
* horizon is much more frequently clear in morning than in evening."
* Oct. 28, 1904
* VIOLET flash
* ". . . what we saw was a flash that was distinctly violet in colour."
* No.2067, Nov.4, 1904
* O'C #193; Fisher #25
* Whitmell admits the simple explanation is not adequate:
* "Mr. Childe's question as to why the flash is often absent, though
* circumstances seem favourable to its production, is not easily answered."
* No.2068, Nov.11, 1904
* Mostyn ("Treadle") notices the symptoms of INFERIOR MIRAGE for shipboard
* flashes (again!)
* "I used to observe that the flash was most often seen when the sun, as
* it approached the horizon, was distorted horizontally and assumed the
* appearance of a gold-fish globe or an egg on its side . . . . On the other
* hand, when the refraction was vertical --- when the sun took on the shape
* of an egg on its end . . . --- the flash was seldom if ever to be seen."
* ("Treadle" was identified as C. Mostyn by Langford in 1901.)
* No.2067, Nov.4, 1904
* Fisher #106, O'C #291
* Wilkins proposes sunlight shining through waves (!) despite Whittle's
* July letter
* No.2067, Nov.4, 1904
* Great line criticizing the "ocean waves" notion of Wilkin [sic]:
* "The horizon may be of sea, land, or cloud. Of course, this utterly
* demolishes Mr. Wilkin's explanation, which on other grounds also is quite
* untenable. Over land the flash might with equal probability be ascribed
* to waves of grass."
* No.2070, Nov.25, 1904
* Another put-down of Wilkins's "waves":
* "If Mr. Wilkins possessed the most elementary acquaintance with the laws
* governing the transmission of light through media of different densities,
* he would see at once that a horizontal ray of light entering a wave-shaped
* body of water would be deflected downward, and therefore could not
* possibly emerge from its opposite face to continue its original course in
* a straight line to the eye of a distant observer."
* No.2070, Nov.25, 1904
* Most, but not all, of Whitmell's GF letters to E.M. during 1904;
* Contains several references to other people's letters, including Childe's.
* SCHERING refutes Julius's anomalous-dispersion theory
* See Mon.Wea.Rev.33,408-409(1905) for a translation.
* Phys.Z. strangely indexes this under "Julius" and not "Schering", which
* explains Fisher's listing it under "Julius" as his #62.
* Hartmann's long refutation of Julius's other anomalous-dispersion
* theories in A.N.4197 mistakenly gives the year as 1904.
* 1 Jan. 1905 issue
* Fisher #62 ("Julius") *and* #129 ("Schering")!
* Mentions GF only in 1 sentence: ". . . der übrigens sehr oft, aber nicht
* immer, im letzten Moment den viel erwähnten grünen Strahl zeigte . . . ."
* Feb. issue
* Fisher #100
* telescopic JUPITER FLASH
* No. 2087, March 24, 1905
* O'C #205; Fisher #41
* Whitmell's comment on Ellison's Jupiter flash
* No. 2088, March 31, 1905
* An exact reprint of Whitmell's E.M. letter [258].
* Thanks to Ray Emery for supplying this!
* Discussion of Whitmell's paper on the Sun's supposed reflection in the sea
* These two items really belong with the Ricco and Forel files, as they
* depend mainly on their work.
* "If one only occasionally watched the sun rise and set, one did not know
* what were unusual phenomena and what were not, and if one then saw an
* unusual phenomenon, one did not recognise it as such, because one did not
* know what the usual appearances were."
* ". . . it was noticeably green for a period of two seconds, not what might
* be called a flash, but lasting a sufficient time for it to be seen that it
* was green; . . . ."
* Fisher #53
* Whitmell's report on rotundity (cf. Forel and Ricco, whom he cites)
* ". . . I have left out of account the influence of refraction. Doubtless
* it would modify some of the results, but would not affect the general
* reasoning."
* "M. Ricco appears to have been the first to observe the contraction in
* the sun's image reflected from the sea." [but cf. Bravais, 1853!]
* Properly, this should be filed with either the Ricco or the
* Forel/Dufours file; but it is here as it logically follows Mr.
* Hardcastle's comments on green flashes (previous item).
* Comment on oral presentation of Goodacre's paper (next item)
* and discussion by Goodacre:
* ". . . Mr. Goodacre said he always saw the flash with unaided vision,
* though he had read that it was much better seen with a binocular."
* "Mr. Hardcastle . . . would describe the duration of the flash as being
* two seconds, but, of course, a far greater amount of the sun was visible
* within two seconds of its rising than ought to be according to the
* movement of the sun. It occurred rapidly, as one saw it rising, evidently
* due to refraction, and not to the movement of the earth."
* Joseph Alfred Hardcastle was a grandson of Sir John Herschel, and worked
* as a professional astronomer (see his obits in JBAA 28, 28-29 (1917).
* and M.N. 78, 246-248 (1918).)
* Fisher #49 (listed under Goodacre); O'C #218
* third mention of VARIATIONS IN DURATION and SIZE of flashes ?
* This is mostly a translation of Schering's Phys.Z. paper, but
* the editor has an introductory paragraph that mentions Tyndall:
* ". . . the green ray seen just as the last glimpse of the sun disappears
* below the sea horizon was originally introduced into meteorology by
* Tyndall as an evidence of the special absorptive power of the aqueous
* vapor in the lowest layer of the atmosphere." He then mentions Julius's
* paper, and Schering's review of it.
* Fisher #130
* REFRACTION SCALED:
* "If we take the horizontal refraction as 32', the factor 1/40 gives
* about 50" for the vertical length of the spectrum of a luminous point,
* such as a star or the tip of the sun when on the horizon."
* "With a telescope it is quite easy to observe, at low altitudes,
* a bluish-green fringe on the upper part of the sun's limb. The
* final development and sudden disappearance at sunset of this dispersion
* phenomenon constitute the green flash."
* Fisher #152
* useless novice observation of sunrise GF
* Fisher #101, O'C #251
* A dubious first-time observation; possible green RAY ??
* ". . . suddenly there shot out from the point where we had seen the last
* of the sun a brilliant flash like a beam of electric light.
* It appeared to flash white, blue, and green in succession . . . ."
* No. 2114, Sept.29, 1905
* Fisher #26; O'C #206? (garbled)
* Jocular account of an eclipse expedition, with passing mention of GF
* "The green flash has excited general interest, and some surprising
* observations have been made. A lady has seen a green flash extend almost
* to the zenith several minutes after the Sun went down, and it has been
* quite common to see the Sun reappear somewhat faintly, but distinctly
* green all over! It is, in fact, not quite easy to separate the real
* green flash from the effects of retinal fatigue, and the writer is not
* sure that he has ever succeeded. The last segment of the disappearing
* Sun certainly changes colour, but the result is not always a brilliant
* green. . . . it is to be wished that some observer returning from an
* eclipse could set up his instrument and get the `green flash' spectrum."
* [pp. 416-417] -- "A.R.H." may be A.R.Hinks.
* Thanks to the NASA ADS full-text search for turning this up!
* Admiral Maclear: (has some earlier refs.)
* Apparently the Admiral sent nearly the same letter to Symons's (see below).
* Here, he says "stars"; there, "planet". There are other minor changes.
* Prof. W.M.Davis's "Elementary Meteorology" cited (p.50).
* The full title is "Knowledge & Illustrated Scientific News"
* conducted by Major B. Baden-Powell and E.S. Grew, M.A.
* (N.B.: this "volume" *begins* on p.315, though it spans a calendar year.)
* O'C #234
* replies to Admiral Maclear (March issue)
* Many interesting observations described, including a sunset with
* multiple flashes. One observation notes the red lower limb.
* "I have seen the green, or rather many-coloured flash also behind the
* mountains at sunset in Egypt; but it is neither so clear nor of such long
* duration when seen over land as at sea."
* Evidence of ADAPTATION:
* "At first the whole of the visible portion of the disc of the sun
* turned intense fiery red. Then when a little more than half the disc
* had disappeared it changed to yellow."
* Good color description:
* "Then when the sun is almost down the whole visible part became greenish
* with violet flashes. Then the rest of the disc becomes a line with deep
* violet at each end, blue next to the violet, and green in the middle parts
* of the line."
* ". . . the altitude above sea level about 55 feet; weather calm, light
* S.W. wind . . . ."
* "I used no dark glass on the telescope."
* Full title: Knowledge and Scientific News (March, 1906)
* CHARLES MOSTYN again -- an experienced and careful observer.
* ". . . in a favorable display . . . the `flash' changes rapidly from green
* to blue and violet . . . ."
* SUNRISE better than sunset:
* ". . . far the finest view of the `green flash' is to be obtained,
* according to my experience, oft repeated, at sunrise . . . ."
* "And the horizon is more apt to be clear and sharp at sunrise than at
* sunset, while the brilliance of the flash to the un-tired eye is
* magnificent."
* "Also, the best shows were when the sun, on the horizon, was much
* distorted by refraction."
* [cf. his E.M. letter where this is made explicit.]
* Admiral Maclear: (has several earlier refs.)
* "The phenomenon is frequently observed, but very little has been
* published about it. . . ."
* [The Editor follows with a quote of the MWR Sept. 1905 paper, which
* mentions Tyndall. This quote continues on the next page.]
* Fisher #81
* CAREFUL about Symons's dates: last issue of each volume (ca. p.210ff.)
* was always in Jan. of following year!
* Admiral Maclear: (has some earlier refs.)
* ". . . it is stated that after sunset every solar beam will be broken up
* into a short vertical spectrum; is this the explanation? if so why should
* the last flash be green? . . . I would like to see that matter worked out."
* Fisher #82
* R.C.CANN LIPPINCOTT's crusade for afterimages begins!
* Fisher #75
* R.C.CANN LIPPINCOTT contradicted by Major George H.Courtenay
* N.B.: the 1854 date is VERY EARLY !
* "I saw it continually on my way from Tasmania, in 1854, in the South
* Pacific. But then it occurred at sunrise . I used to get up to
* observe it morning after morning."
* "[Major Courtenay's observation of the green ray at sunrise . . . seems to
* dispose of Mr. Lippincott's argument that the appearance is due to fatigue
* of the eye . . . , a suggestion often made before seeing the phenomenon but
* rarely upheld by one who has actually observed it. -- Ed. S.M.M.]
* NOTE that this is a VERY EARLY OBSERVATION, before Joule!
* Fisher #31
* Col. Markwick reports a small naked-eye flash
* This is only the last paragraph of a long letter mainly on other topics
* No. 2134, Feb. 16, 1906
* Fisher #85
* FIRST REVIEW ARTICLE -- SCALED REFRACTION calculated again (1/72)
* N.B.: cites *nothing* but English journals!
* Dr. Arthur A. Rambaut, F.R.S.; earliest refs. are to Nature in 1883.
* Rambaut had been Radcliffe Observer since 1897.
* first mention of violet as complement to yellow?
* "It was then quite unmistakable, and those who are so fortunate as to
* see it, as I and several of my fellow-passengers on the Durham Castle
* did on that occasion, will not, I think, retain any lingering doubts
* as to the objective character of the phenomenon."
* Another independent inventor of the OCCULTING DIAPHRAGM!
* "This is an observation by which any possessor of a telescope can easily
* satisfy himself that the flashes are due to atmospheric dispersion of
* light, and is at least less expensive than building a Wesleyan Chapel
* with horizontal openings in the belfry." (cf. Whitmell's RF paper.)
* The curious figure purporting to show how the textbook flash is formed
* contains only red, yellow and blue -- suggesting that Rambaut made
* the common error of thinking that blue + yellow makes green.
* Fisher #122 and #123
* Cann-Lippincott again insists on afterimages, even at sunrise!
* Lippincott pursues the same line in QJRMS
* This letter is dated March 24, 1906.
* Fisher #73
* Gregg starts a round by inquiring about the green ray's visibility
* No. 2141, April 6, 1906
* H.P.Hollis replies to Gregg, citing Rambaut's first installment.
* Note: this heading is a sub-head of a long letter of many parts; the
* general heading is "Magnitude of the fixed stars".
* No. 2142, April 13, 1906
* Whitmell replies to Gregg, and cites papers in Leeds Astr.Soc.
* No. 2142, April 13, 1906
* Variability. . .
* "It should be noted that the green ray . . . is not always seen even when
* the sun sets at sea on a perfectly clear horizon."
* Fisher #7
* Unsigned editorial by H.R.Mill, with a synopsis of Verne's story
* "We have seen it only a dozen times in twenty years. . . ."
* Mill seems to believe the "old Highland legend".
* Cited with title in Kimball's "Recent Papers," MWR 34, 219 (May 1906)
* Fisher #97 and 98
* GREEN RAY observation
* "The common `green,' or as I would rather call it `blue' flash which I
* have seen, perhaps a hundred times, is undoubtedly caused in the way
* described by Dr. Rambaut, but there is another phenomenon which I have
* seen on a few occasions, which is almost as certainly caused by
* atmospheric absorption. In it the upper part of the sun's disc when
* setting becomes a vivid green for several seconds before disappearing,
* and in the light then given objects of a green colour appear with
* extraordinary vividness. Probably closely allied with this phenomenon
* is one which I have seen here on two or three occasions, when the whole
* sky became filled at sunset with what seemed to be a green mist, which
* produced the most lurid effects." ("here" = Kodaikanal)
* Fisher #137
* (mostly useless)
* Fisher #32
* first ref. to Mrs. Steel
* "As another example of the mention of the Green Ray in fiction, I may
* instance Mrs. F. A. Steel's novel, `Red Rowans.'"
* LIPPINCOTT refuses to give up!
* Fisher #76
* Capt. Carpenter replies to Lippincott in QJ, who responds (next item)
* "The extraordinary explanation of the above . . . by Mr. R. C. Cann
* Lippincott, needs some correction. . . . a complementary coloured spot will
* only fade away slowly, whereas the green flash is momentary, seldom
* exceeding 1 1/2 seconds."
* This is in the July issue.
* Lippincott responds to Carpenter with nonsense
* Another report from Southport !
* This seems to be associated with looming; needs to be investigated.
* Cites his earlier report in E.M.No. 2114, p.183.
* No. 2155, July 13, 1906
* Fisher #27
* Lippincott again
* This is a further reply to Capt. Carpenter's letter in the July issue.
* Fisher #74
* ramblings about particulate EXTINCTION and IRRADIATION
* "[. . . the question of the infrequency of the phenomenon is an
* interesting one, on which, perhaps, more can be said. -- Ed. S.M.M.]"
* "The duration may be largely affected by the observer's latitude and the
* extent by the refractive condition of the air."
* Fisher #153
* "I cannot believe that the phenomenon has ever been seen, unless the red
* edge or red colour or red ray of the rising or setting sun has been first
* seen above the horizon."
* A "convert to the physical theory" testifies for Rambaut
* Fisher #80
* Whitmell sees a a red flash below cloud
* (Alex.Thurburn is still confused)
* Varying width of green rim (N.B.: now Jan.1907)
* Fisher #46
* Hansky's sunrise flash of Sept. 4, 1900, reprinted by Rodolphe Radau
* The GF report is an extract of Hansky's report in Janssen's Note on
* his Mont Blanc observatory in the 1901 Annuaire.
* An English translation of this item appeared in the Annual Report of
* the Board of Regents of the Smithsonian Institution, for the year ending
* June 30, 1906 [GPO, Washington, DC (1907]). Unfortunately, Radau's
* initial appears there as "H.", not "R." This error was then propagated
* by the Nov. 23, 1907, supplement to "Scientific American", which abstracted
* the English translations of this and earlier Radau articles on Janssen,
* omitting Hansky's GF observation.
* Rodolphe Radau spent much of his life working at "Revue des Deux
* Mondes". He was part of the German community in Prussia, but moved to
* Paris after studying math and astronomy at Königsberg.
* The Editor's patience is exhausted! LIPPINCOTT's last gasp
* Note the Editor's sermon at the end!
* Fisher #77
* Adrien Guébhard won't admit defeat, and gets in another lick:
* "Quant au prétendu météore du rayon vert , il n'a pas davantage
* d'existence colorée objective : c'est la simple ombre portée,
* au milieu du crépuscule rouge, d'une pointe se détachant sur
* le disque solaire à sa disparition . . . ."
* This article is mostly about color perception; only 1 paragraph on GF.
* NOT a green flash -- completely PHONY description.
* "As the sun there [Egypt] descends nearer and nearer to the horizon,
* apparently hastening to disappear behind one of the Libyan hills, as if
* burying itself in the sand at their base, the immensely enlarged flaming
* disc suddenly becomes, for an instant, of a brilliant green colour, and
* immediately a series of green rays suffuses the sky in many directions,
* well-nigh to the zenith." (All a fantasy; certainly not seen.)
* Fisher #109, O'C #98
* Joseph Offord's awful paper reprinted in E.M.
* No.2186, Feb.15, 1907
* Fisher #110
* an account of Nijland's A.N. paper; first mention of GF in H&D?
* exact citation is vol.4, no.2, Maart 1907
* Thanks to Ernst Raimond for a copy of this!
* The second half of this letter concerns a TELESCOPIC green flash
* "In watching the sun set to-night beneath a land horizon, through a
* small telescope without eye-screen . . . it was evident that this green
* border was the more refrangible part of a spectrum ."
* [Looks like No. 2203 or 2205 -- can't read date on photocopy: June ?]
* Whitmell's GF letter to E.M. published on 5 July 1907;
* refers to Allison's letter, p.494
* Whitmell discuses the prolongation of a flash at the Arctic Circle,
* calculating 12 minutes (6 each before and after midnight).
* "For such a duration the word `flash' seems scarcely suitable; but the
* disadvantage of the word `ray' lies in the fact that it conveys to many
* persons the impression that a long green streamer is seen shooting up
* towards the zenith. This is unfortunate, as observers are led to look
* for something which never occurs as part of the green flash, properly
* understood."
* Reprint of Whitmell's GF letter to E.M., 5 July 1907;
* refers to Allison's letter, p.494
* Fisher #154; not read (hence the error in journal name)
* He thinks a GF is a SOLAR PROMINENCE
* He sees flashes with 10x telescope; but thinks the last previous
* observations were those of Exner in 1902 and Dorn in 1903.
* "Vermutlich ist er veranlaßt durch aufflammende Gasausbrüche am
* Sonnenrande, sogen. Protuberanzen besonderer Art." At sunrise,
* "Grüne Randerscheinungen konnte ich . . . mehrmals feststellen.
* . . . Es handelte sich dabei um eine ganze Korona grünlicher Flammen, die
* sich auf je etwa 30 Grad heliographischer Breite nördlich und südlich
* (im Sonnenbild links und rechts) vom Sonnenäquator aus erstreckten."
* (The continuation of the article on p. 329 is about ordinary solar
* activity.)
* Aug.1, 1907 issue
* Col. Markwick's review of atmospheric optics
* One long paragraph here devoted to the GF: ". . . the sight of it is
* decidedly rare, and should be treasured up in the memory afterwards."
* "It generally lasts about a couple of seconds, and the change of colour
* is most impressive. A binocular vastly assists the eye in the observation
* of the phenomenon, which is doubtless due to atmospheric dispersion . . . ."
* No.2212, Aug. 16, 1907
* HARTMANN's refutation of Julius's wild applications of anomalous
* dispersion to everything in sight. He cites Schering's 1904
* refutation of the GF model.
* This item is followed by a letter from the infamous H.H.Kritzinger!
* Allison's letter, describing the MOCK MIRAGE phenomena
* "It was curious to note how the refraction of the air caused both
* notches and projections to appear upon the limbs -- especially the upper
* one -- which notches and projections remained permanent for one or two
* minutes. Sometimes two notches would approach one another, and finally
* cut off, apparently, a piece of the luminous disc which floated above the
* rest of the sun. . . . the uppermost part of the projections on the upper
* limb continually shot out green flakes . . . ."
* No.2221, Oct.18, 1907
* Whitmell confirms what Allison's letter, p.237, reports
* Whitmell recommends using a telescope to see the green and red "flames".
* No.2222, Oct.25, 1907
* GROFF's works reprinted
* The GF papers are on pp. 171-180, 190-196, 221-224, 225-227, 249-258 and
* 258-272. The biographical note is in pp. I-IV.
* use of PINHOLE to attenuate the Sun
* Maxwell Hall
* Fisher #52
* our "last glimpse" of R.C.CANN LIPPINCOTT !
* "I am convinced that the so-called `green flash' is the after-image or
* visionary image of the impression produced on the retina by the last rays
* of the setting, or by the first rays of the rising sun, seen in the
* complementary blue-green colour."
* (Letter dated 10 Feb. 1908)
* Whitmell relays an observation by Ivo Gregg in Egypt
* ". . . where he has been staying with Professor Flinders Petrie."
* ". . . in the Libyan desert, near Wadi Halfa, he saw, with the naked
* eye, at sunset, the Green Flash, a phenomenon for which I had asked him
* to look out. Just as the solar disc disappeared, its tip assumed a fine
* green colour."
* As Whitmell asked Gregg to observe, this might be the cause of Petrie's
* 1914 report?
* The same item, reprinted in the Leeds Trans.
* Thanks to Ray Emery for supplying this!
* 2 minor mentions of GF observations in a long article on other matters
* Prof. Ward calls it "the `green ray'" (in quotes) on pp. 335 & 339.
* Oct. issue.
* Fisher #145
* green rim + green flash
* O'C #271
* R.C.Cann Lippincott sees something at last: GF or Cornsweet effect?
* Fisher #78
* ORANGE LINE becomes GREEN BAND at Southport !
* "The disc was much distorted as it sank; for the last 30 seconds or so
* it seemed an unvarying bright orange line; then the orange simply faded
* and all but disappeared. I was just about to register one more failure
* when a distinct and bright green band took the position and apparent size
* of the orange of about 20 seconds previously; it continued for perhaps
* seven seconds and then gradually faded away."
* Fisher #70
* GF with inf.mirage, 10. August 1909 at Zandvoort
* ". . . ein Spiegelbild auf der Meeresfläche entstand. Nur ungefähr eine
* Sekunde vor dem völligen Verschwinden w u r d e d a s l e t z t e
* s e g m e n t d e r S o n n e g l e i c h z e i t i g m i t d e m
* S p i e g e l b i l d e grün."
* Not certain about details, "da mir die Erscheinung neu war und mich zu
* sehr überraschte." (typical BEGINNER'S REACTION)
* Also a good story about the "junge Dame": "Im Augenblick, als die Sonne
* verschwunden war, wandelte sie sich mit dem Ausdruck höchsten
* Erstaunens zu mir und sprach nur das eine Wort: grün!"
* Ellison Hawks reports a 6-second flash, "peacock blue" at end
* Fisher has "Hawkes" in error, and F.K. does too.
* No. 2317, Aug. 20, 1909
* Fisher #54
* Whitmell asks for an explanation of "the rarity of the flash although
* circumstances are apparently quite favourable for its appearance."
* "I have seen the green flash at least a score of times, but failures
* have outnumbered successes.
* "The difficulty of the problem is enhanced by the fact that a
* telescope directed to a low sun in a clear sky invariably exhibits
* atmospheric dispersion, the upper limb being fringed with bluish-green,
* the lower with orange-red, and the green flash is simply the ultimate
* development of the former colour upon the tip of the setting sun."
* No. 2318, Aug. 27, 1909
* Reprints of the two E.M. letters by Hawks and Whitmell
* Hawks letter [70] dated Aug. 14, 1909
* Thanks to Ray Emery for supplying this!
* Reprints of the two E.M. letters by Hawks and Whitmell
* Whitmell letter [98] dated Aug. 27, 1909
* Thanks to Ray Emery for supplying this!
* pompous presentation of GF in a description of twilight phenomena
* must be # 1035, from F.K.'s citation
* O'C #90 -- there is a second installment on pp. 753-756, he says.
* LIPPINCOTT vs. WHITMELL in E.M. (1909)
* "R. Claude Lippincott" sees a green flash at last; but maintains it is
* due to "simultaneous physiological contrast".
* No. 2322, Sept. 24, 1909
* Fisher #79
* Whitmell replies to Lippincott:
* No. 2323, Oct. 1, 1909
* Lippincott augments his description, asserting "simultaneous contrast".
* No. 2325, Oct. 15, 1909
* Whitmell replies to Lippincott:
* No. 2326, Oct. 22, 1909
* Cann Lippincott has his final say in E.M., shooting himself in the foot
* as he does so:
* "With reference to Mr. Whitmell's suggestion that I should study the
* appearance of the sun through a telescope when it is low or setting, I may
* remark that the telescope would introduce a new condition, which would
* produce a modification of the natural phenomenon. My present residence
* is not well situated for observations of either sunrise or sunset, because
* it is surrounded by hills on which there are trees, which interfere with
* the view of the sun about the time of sunrise or sunset."
* No. 2328, Nov.5, 1909
* CARLO BONACINI's early GF credential
* Short abstract of a paper presented in 1907: he saw the red and green
* rims, and realized that they should be attributed to atmospheric
* dispersion; and "that to this is connected, at least in part, the noted
* and discussed phenomenon of the `green ray'."
* Review of Groff's collected works
* Probably this belongs in the "biographies" file, but is included here
* for Ernst Andersson's comments on Groff's GF work: ". . . une série
* d'études très intéressantes." He seems to think it Groff's best work,
* and quotes at some length from Groff's conclusions.
*
* MANY THANKS to Orell Witthuber, Fachgebiet Aegyptologie der
* Philipps-Universität (Marburg, Germany) for providing this useful
* reference!
* LORD KELVIN's first GF
* ". . . the first time I saw it, it passed quickly from white through green,
* to intense violet. The sun was very clear, with very little of the
* redness which we generally see at sunset." That was in 1896, before the
* sunrise flash of 1899.
* (See next 2 papers for discussion.)
* Fisher #65, O'C #70
* little more info from Silvanus P. Thompson; comments on violet
* Fisher #24
* Whitmell quotes most of Kelvin's Nature paper; further comments on violet
* Described in part of one paragraph on p.246
* This is mostly about other weather phenomena, esp. anti-crepuscular rays.
* "Hochgebiete" turns out to be 1500-2000 m.
* Full title: Das Weltall, Illustrierte Zeitschrift für Astronomie und
* verwandte Gebiete, herausgegeben von Dr. F.S.Archenhold, Direktor der
* Treptow-Sternwarte
* ". . . about ten (or less) seconds after it had disappeared a bright green
* single flash, just like a railway signal lamp, but brighter far, met our
* view. . . "
* Fisher #5
* 3 GFs on an island horizon
* ". . . the reputed rareness . . . is a striking proof of the unobservant
* habits of most people."
* error: "Whitmill" for Whitmell
* Fisher #99
* KREBS's crank connection of green rims with solar activity
* ". . . eine grüne Umrandung besonders des Ostrandes der untergehenden
* Sonne . . . der Westrand, solange es sichtbar war, gewöhnlich nicht die
* gleiche Erscheinung erkennen ließ." He seems to have used the low
* Sun simply to make use of the atmospheric extinction to render it
* observable in a 3-inch telescope. The reappearance of an active
* region "am Ostrande der Sonne war . . . begleitet von ausgeprägter
* grüner Strahlung. Besonders deutlich trat sie auf bei dem ersten
* Akte des Sonnenunterganges hinter einer 3° hohen bleigrauen Bank.
* Diese erwies sich in der Folge als der total reflektierende Teil einer
* Sprungfläche der Atmosphäre. Denn unterhalb des etwa gradbreiten
* dunklen Bandes, hinter dem die Sonne verschwunden war, trat sie wieder
* hervor. Doch war die Scheibe erheblich breiter und kirschrot statt, wie
* vorher, orangefarbig. . . . die grüne Berandung stellt sich vor und
* nach dem Passieren des dunklen Bandes, das sein Auftreten der
* Totalreflexion verdankte, am natürlichen Ostrande der Sonne ein, während
* sie an dem künstlich von diesem Bande geschnitteten Ostrande ausblieb."
* Nov. issue.