* 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 Holboldt 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)
* also known as Antonio Galateo, Galateus Antonus, etc.
* 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
* (Panormi = Palermo)
* Cited by Minasi; and, following him, P&E. 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
* I have not seen this.
* 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 1 Naturae, siue de Morgana Rheginorum in Freto Mamertino,
* siue Siculo" -- here, on p. 801, we have "Vocant autem Rhegini hoc
* spectaculum Morganam," followed by Angelucci's letter.
* 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 paper on
* Harriot.)
* 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)
*
* MIRAGE OBSERVATIONS
*
* 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.
* 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
* BOSCOVICH translated into French
* The same section numbering is used as in the original. There is a
* detailed map included, showing the region surveyed.
* 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."
* 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.)
* 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.
* 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.
* 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 the "vanishing line"; 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."
* This is actually a Postscript (Nachschrift ) to the Fifth Letter,
* beginning on p. 40, and dated 20 April 1779, from Zirknitz.
* Typographical note: this is all set in Fraktur, with little e's over
* the vowels as umlauts.
*
* Full title page reads:
*
* Herrn Tobias Grubers,
* Weltpriesters und k. k. Bau- und Navigationsdirektors
*
* 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
*
* [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
* 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!
* Here, 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. . . .
* Interestingly, he does invoke total internal reflection (p. 53).
*
* 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, appending notes to it -- 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)
*
* 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.
*
* Special thanks to the ILL people for this one at last!
* 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
* 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.
* 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"!
* 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 a 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."
* 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.
* Thanks to Maria Toscano for supplying the citation to this, and
* helping with the translation!
* 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."
* EARLY OBSERVATION & EXPLANATION OF INFERIOR MIRAGES
* 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 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."
* 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.)
* 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 crank theory (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 additional 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 of 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).
* 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, 1797 -- 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.
* GASPARD MONGE explains the INFERIOR MIRAGE as total internal reflection,
* and reports REFLECTED RAINBOWS
* Cf. Le Gentil (1789) for "se mirer".
* 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!)
* 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.
* EARLY MIRAGES
* summaries of the work of others by Ludwig Wilhelm Gilbert:
* EARLY EXPERIMENTAL DEMONSTRATION OF MIRAGE
* Abbé Tobias Gruber (Grüber?) -- see his 1786 paper.
* QUANTITATIVE MEASUREMENTS of MIRAGES and VARIABLE REFRACTION
* Reinhard Woltman (Not "Woltmann", says Pogg.)
* Gilbert attributes the term "Spiegelung" to Woltman.
* [It seems that Woltman was Brandes's supervisor in 1794-95.]
* 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."
* 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 des
* Wasser um 2° F. kälter als die Luft, so fand Hebung der Strahlen
* und nie eine Spiegelung herabwärts statt."
* Note that Gilbert prints double-s as a long followed by a short s.
* EARLY THEORY OF MIRAGE
* Abbé Tobias Gruber (Grüber?)
* 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.
* 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.
* 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".
* 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.
* William Beauford's perceptive review, just before Wollaston's
* Probably this should be the first entry in the FOG file. However, his
* perceptive remarks requite 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:
* Here 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]
* 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:
* "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).
* 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 rowboat 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 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)
* Then there is a Postscript (pp. 155-156) that continues the discussion,
* finding the image position.
* 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
*
* ". . . 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]
*
* 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."
*
* 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!
* BIOT + ARAGO's observation (reported in BIOT's MIRAGE book)
* "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 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.); 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!
* August Schmidt's (1878) comments are appropriate.
* [cf. the German treatment by Brandes, 1814.]
* 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.
*
* Note that the drawings are by Mathieu (cf. Delambre, 1827)
* Jean Baptiste Biot
* Some of the same figures appear in Biot's textbook:
* The miraged man (Fig. 41); the distorted sunsets (42 & 43) 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)
* This 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 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].
* The German treatment of Biot's monograph, by Brandes -- part 2
* 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
* 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 for inversion
* 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?"
* 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."
* 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)
* 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).
* 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.)
* Dr. William Kelly seems to have been as sharp an observer as Willard Fisher
* 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."
* Kelly grants that the temperature difference between water and air is
* the main factor, but thinks humidity plays a part as well. He notes
* that mirages are favored by calm, but "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.
* On the whole, a careful, cautious argument; should be taken seriously.
* No.8, August, 1846.
* 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.
* 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".
* 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.
* 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)
*
* 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.]
*
* 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)
*
* 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.
*
* 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)
*
* 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)
*
* Mostly superior mirages, with DRAWINGS
* "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?
* cf. Büsch, 1800, for a similar observation.
* 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)
* 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 . . . ."
*
* 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)
* 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.
* ". . . das erste Bild [der Sonne] welches . . . zu einer sehr schmalen
* Ellipse abgeplattet erscheinen müßte . . . ."
* Available at last from
* http://bibliothek.bbaw.de/bibliothek-digital/digitalequellen/schriften#A9
* The volume for 1860 was published in 1861. Meeting date: 12. Juli
* [cf. Bouguer (1749) and J.de Graaff-Hunter (1913)]
* VERDET translates Kummer's paper
* The section is headed "Mémoires sur la physique publiés a l'étranger.
* Extraits par M. Verdet."
* (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.)
* 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".
* John Parnell's MULTIPLE-IMAGE MIRAGES at Folkestone, 13 April (1869)
* "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."
*
* There had been "fog" in the morning, but at 2 pm "in the course of a few
* minutes the fog had disappeared, leaving the atmosphere in a state of
* unusual transparency."
* ". . . 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".
* 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
* "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." (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)
* "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.)
* 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, a a great elevation, of a stratum in which there
* was a comparatively rapid diminution of refractive index with increasing
* height." [pp. 576-577]
* 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."
* 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."
* 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!)
* 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
* 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.
* "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."
* 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.
* [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
* Note that he admits Wiener's writeup is better
* [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
* THE DEFINITIVE 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.
* A copy of Willem Fortuyn's engraving for Minasi is Fig. 1 (p. 203)
* There is an extensive annotated bibliography at the end.
* 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.]
* 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.
* 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.
* A table (p. 123) compares the various observations.
* 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)
* Claimed mirage of a rainbow, but impossible at 45° altitude
* 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."
* 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 Acrtic 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
* Additional Arab mirage refs. to supplement Erdmann
* 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).
* 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!
* 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)
* 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.
* 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."
* 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 at airport
* Describes LABORATORY DEMONSTRATION of mirages
* 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
* 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.
* Useful comments about "FOG", which he seems to equate to the Fata-Brumosa.
* Useful comments on earlier reports in BSAF, too.
* 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. 1989; then
* (c.1996) was sold to Times Mirror Magazines, Inc.. It is still
* apparently 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
* 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)
* GOOD DRAWINGS showing the change in mirage with DISTANCE of ship
* 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
* 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]
* 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 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."
* 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
* 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 . . . ."
* 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.
* Available on the Web at
* http://www.optometrists.asn.au/ceo/backissues/vol86/no2/2043
* 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 (see cover!)
* Contains comments by ATY. Nice mock-mirage GF shown, too.
* No. 11 (Nov. issue)
*
* 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".
* 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.
*
* 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 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.
* 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.
*
* 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 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
* 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."
* DOUBLE DARK BAND sketched -- just sup. mirages of the ocean?
* "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 "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 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.
* 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.
* 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.
* 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.
* 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.
* Thanks to ADS for making this available!
* 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
*
*
* 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."
* 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".
* NEWCOMB
* Surprisingly full of errors.
* BEMPORAD's Enzyclopädie 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!
* The publication date is uncertain; I have not seen the title page
* of this volume. Bemporad's contribution is dated December 1907, so
* the actual publication date must 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/ ]
* 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, 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!
* 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
* DIP, SUNSET in Chapter 10,
* "Determinations of position in the local reference system"
* 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!
* 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.
* not a book, but a textbook-style tutorial article; so placed here
*
* 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 no now 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.
* 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.
* 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.
*
* original edition of Minnaert's book
* first English translation:
* 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
* 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 not 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 Bromosä. 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.
* 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
* 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" description; no numbers or diagrams.
* 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 . . . .