(or the castles of the "fairy Morgana"), a remarkable optical illusion depending on mirage or unusual atmospherical refraction, which has been described by various philosophical writers and travellers as observed in the Straits of Messina, between the coasts of Sicily and Calabria. The following account of this aerial phenomenon is taken from Minasi's dissertation on the subject, published at Rome in 1773. "When the rising sun shines from that point whence its incident ray forms an angle of about 45° on the sea of Reggio, and the bright surface of the water in the bay is undisturbed either by the wind or the current,—a spectator standing upon an eminence in the city, with his back to the sun and his face to the sea, beholds in the water, as in a catoptric theatre, various multiplied objects, i.e. an indefinite series of pilasters, arches, castles well-delineated, regular columns, lofty towers, superb palaces with balconies and windows, extended alleys of trees, delightful plains studded with herds and flocks, multitudes of men on foot and horseback, with many other strange images, all in their natural colours and proper actions, passing rapidly in succession along the surface of the sea during the short period of time while the above-mentioned causes remain. But if, in addition to the circumstances described, the atmosphere be highly charged with vapour and dense exhalations, it then happens that in this vapour, as in a curtain extended along the channel to the height of about thirty palms, and nearly down to the sea, the same objects are beheld not only reflected from the surface of the sea but likewise in the air, though less distinct and well-defined. 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." It is further shown by Minasi, from observations of the coast and town of Reggio, that the images of the Fata Morgana are derived from objects on shore. He tells us that he had beheld this magnificent spectacle three times; and although his account of it and those of other writers differ considerably from each other, these variations are only such as may be attributed to different conditions of the atmosphere at the time of the respective observations. That some of these descriptions may have received a certain degree of embellishment from the imagination, is not improbable; but there is certainly no reason to impugn—as some have done—their general accuracy. It may be observed, however, that the remarks of Minasi upon the causes of the several phenomena of the Fata Morgana are more fanciful and ingenious than satisfactory. It seems that the phenomenon in question appears to depend upon the calmness of the sea, and one or more strata of superincumbent air differing in refractive and consequently in reflective power; and that the confined situation of the sea in the Straits of Messina is peculiarly favourable to the development of the exciting causes of the phenomenon. For a more particular account of the Fata Morgana, the reader is referred to Nicholson's Journal, vol. i. 4to, p. 225, &c. Similar in character is the mirage observed in the great sandy plains of Persia, of Asiatic Tartary, in Lower Egypt, and on the plains of Mexico, &c.

In the Philosophical Transactions there is an account of a very singular instance of atmospheric refraction which occurred at Hastings, when the coast of Picardy, which is between 40 and 50 miles distant from that of Sussex, appeared close to the English shore. The sailors and fishermen, in amazement, crowded to the beach, and at length began to recognize several of the French cliffs, and were able to point out places they had been accustomed to visit. From the summit of the eastern cliff the spectator at one glance could see Dungeness, Dover cliffs, and the French coast all along from Calais to St Valery; or as some affirmed, as far to the westward as Dieppe; and by aid of the telescope elevated objects on the French coast, such as buildings and trees, were readily discerned.