liable to be strikingly altered by a change of temperature and humidity, so that a hill which at one time appears low, may at another be seen towering aloft; and a city in a neighboring valley, may from a certain station be entirely invisible, or it may show the tops of its buildings, just as if its foundations had been raised, according to the condition of the aerial medium between it and the spectator. [Illustration: Fata Morgana at Reggio.] Of all instances of spectral illusion, the _fata morgana_, familiar to the inhabitants of Sicily, is the most curious and striking. It occurs off the Pharo of Messina, in the strait which separates Sicily from Calabria, and had been variously described by different observers, owing, doubtless, to the different conditions of the atmosphere at the respective times of observation. The spectacle consists in the images of men, cattle, houses, rocks, and trees, pictured upon the surface of the water, and in the air immediately over the water, as if called into existence by an enchanter’s wand, the same object having frequently two images, one in the natural and the other in an inverted position. A combination of circumstances must concur to produce this novel panorama. The spectator, standing with his back to the east on an elevated place, commands a view of the strait. No wind must be abroad to ruffle the surface of the sea; and the waters must be pressed up by currents, which is occasionally the case, to a considerable height, in the middle of the strait, so that they may present a slight convex surface. When these conditions are fulfilled, and the sun has risen over the Calabrian heights so as to make an angle of 45° with the horizon, the various objects on the shore at Reggio, opposite to Messina, are transferred to the middle of the strait, forming an immovable landscape of rocks, trees, and houses, and a movable one of men, horses, and cattle, upon the surface of the water. If the atmosphere, at the same time, is highly charged with vapor, the phenomena apparent on the water will also be visible in the air, occupying a space which extends from the surface to the height of about twenty-five feet. Two kinds of morgana may therefore be discriminated; the first, at the surface of the sea, or the marine morgana; the second, in the air, or the aerial. The term applied to this strange exhibition of uncertain derivation, but supposed by some to refer to the vulgar presumption of the spectacle being produced by a fairy or magician. The populace are said to hail the vision with great exultation, calling every one abroad to partake of the sight, with the cry of “Morgana, morgana!”