THE MIRAGE.

Akaroa Mail and Banks Peninsula Advertiser, Volume 4, Issue 350, 25 November 1879, Page 2

THE MIRAGE.

According to aparagraph in the " Lancet," a' singular/,' example of the optical illusion known as tbe mirage recently occurred at Tenby. A photographer happened to take a photograph of the church spire of that town; whilst-doing so he observed nothing extraordinary, but on the development of .the plate there appeared across the spire the distinct outline of a bpat with colors flying fore and aft. It was ascertained "that exactly at the time the photograph was being taken, & gunboat launched from the Pembroke Dock, exactly answering in appearance toto the outline which >so mysteriously appeared on the photographer's pi ate. It is an undoubted scientific fact that where there happens, from any meteorological cause, to be a stratum of atniosphere of considerably higher power than that immediately below it, the upper stratum acts as a kind of mirror, and may reflebt objects at .a very considerable distance. The extraordinary instance of this phenomenon'ia the wellknown case of Captain Scoresby, who r ', whilst engaged in the whale fishery, obtained the distinct effigy of his f athers's ship suspended in the air, and thus ascertained the fact; of which he had been previpuly unaware, that his father was in the same, qiuwter of the globe as himself. Th& vessel m "question turned oitt to have been--30 mifes distant when its refracted image waa seen. In the hot countries of the south and <3ast the; mirage isfreqnently.seen, and in the Straits of Messina it has acquired the name of .the ' ( Fata! Morgana," from the ancient superstition of its fairy origin. It is, perhaps, a little doubtful whether, if weaccept the apparently truthful account of travellers, the phenomenon of the mirage is entirely explained by the theory of refraction. -Very frequently the_incorporal but realistic visions of thejair are evidently exact images of objects at a distance. But on the coast of Sicily, we are told, the phantoms often take the fdrm of magnificent palaces, stupendous castles, and vast armies of men on foot or on horseback, objects which can scarcely be supposed tohave their counterpart on the adjoining shores.- Again; in the African desert, when the mirage appears in its most cruel form, and the exhausted traveller is cheated by ( the delicious image of distant greves and fountains, it seems at least likely that the illusion arises from a morbid and feverish condition of the retina of the observer, such as that which produces,! for example, the , frightful spectres of ' k delirium tremens," ' rather than from the refraction in the atmosphere of some actual oasis. In some caees, indeed, in which the mirage has been obeerved in the desert, the distance from any real oasis must have been immense.—Globe. .