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PHYSICAL GEOGRAPHY. 



considerable height above the horizon, whereas they are frequently not to be seen in clear 

 weather from the high lands above the town. A much greater breadth of coast also 

 appeared than is usually observed under the most favourable circumstances. The 

 ordinary refractive power of the atmosphere is thus 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 neighbouring valley, may from a certain 

 station be entirely invisible, or it may show the tops of its buildings, just as if its founda 

 tions had been raised, according to the condition of the aerial medium between it and 

 the spectator. 



Fata Morgana at Itcggio. 



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 has 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 fre 

 quently two images, one in the natural and the other in an inverted position. A com 

 bination 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 vapour, the phenomena 

 apparent on the water will also be visible in the air, occupying a space which extends 



