FATA MORGANA, is the name given to an optical phenomenon, sometimes seen in the straits of Messina, between the Island of Sicily and the Italian coast. This remarkable phenomenon, which has not hitherto received any explanation, has been described by Kircher, Angeluc ci, Scotus, Giardina, Gallo, Leanti, Brydone, Swinburne, and F. Antonio l\linasi, the last of whom published a dis sertation on the subject at Rome, in 1793.
After having observed the Fata Morgana three times, INlinasi has given us the following description of it, which NVC believe to be the most correct that had hitherto been published.
" When the rising sun," says Minasi, (c shines from that point whence its incident ray forms an angle of about 45 degrees on the sea of Reggio, and the bright srixface 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 appears in the water, as in a catoptric theatre, various multiplied objects ; viz, numberless series Of pilasters, arches, castles well delineated, regular co lumns, lofty towers, superb palaces with balconies and windows, extended valleys of trees, delightful plains, with herds and flocks, armies of men on foot and horseback, and many other strange figures, in their natural colours, and proper actions, passing rapidly in succession along the sur face 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 and waves, or rarefied by the sun, it then hap pens, that in this vapour, as in a curtain, extended along the channel to the height of about four or five-and•twenty feet, 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 hazy and opaque, and at the same time dewy, and adapted to form the iris, then the above mentioned objects will appear only at the surface of the sea, as in the first case, but all vividly coloured or fringed with red, green, blue, and other prismatic colours." Minasi divides these phenomena into three classes; the marine morgana, the aerial morgana, and the pris matic morgana ; and he endeavours to prove, that all the appearances are representations of the objects upon the two Coasts. He considers the sea as an inclined speculum, on account of the rapid current which runs through the straits ; and he supposes it to be divided into different planes, by the contrary eddies which take place when the current changes its directioh. He ascribes the aerial mor gana, to the refractive and reflective power of effluvin suspended in the air.
Many other phenomena of a similar kind, have been long observed under the names of Looming and Mirage. In our article atmosphere, we have mentioned a very sin gular phenomenon observed by Dr Vince of Cambridge ; and Dr Buchan has described another in Nicholson's Jour nal, vol. xiv. All these phenomena obviously arise from the rarefaction of the air in the neighbourhood of the sur face of the sea, in consequence of which, a distant object appears to be depressed instead of elevated by the refrac tion; and it is sometimes seen both depressed and eleva ted, one of the images having in general an inverted po sition. Dr Wollaston has investigated this subject with much ingenuity, and has shewn, that this class of pheno mena may be imitated, either by viewing a distant object along a red hot poker, or through a saline or saccharine solution, with water and spirit of wine floating upon it. See Nicholson's Journal, vol. i. 4to, and vol. xiv. page 310, 8 vo. Wollaston, Phil. Trans. 1798. Gilbert's Journal, vol. xvii. p. 183. Dr Thomas Young's natural Philosophy, vol. i. p. 441, 442. Vince, Edinburgh Transactions, vol. vi. p. 245. ,Biot, Mem. de ['Institut.; and our articles ATMOSPHERE and REFRACTION. (Vr)