MIRAGE. 



565 



MIRAGE* In early times the appearance of 

 images in the air was referred to as " atmos- 

 pheric exhalations," condensing into phantom 

 armies men, cattle, buildings, and other ob- 

 jects, which the superstitious element in hu- 

 man nature soon construed into supernatural 

 signals of approaching disaster. The strait 

 that separates Italy from Calabria is celebrated 

 for the frequence of these displays, and the 

 name "Fata Morgana" conferred upon them 

 by the Italians sufficiently indicates that they 

 were regarded as the productions of a kind of 

 fairy whose good-will toward humanity was 

 looked upon as doubtful. At Poitiers in 

 France a priest was once preaching to a con- 

 gregation in the open grounds about his church, 

 and, while he was recounting the miracle of 



the images, more recently varied by the phan- 

 tom train occasionally seen by the passengers 

 accompanying that upon which they are trav- 

 eling. Twenty miles of water separates the 

 coasts of France and England, and each is to 

 the other tar below the natural horizon, yet 

 they sometimes appear across the channel, so 

 like reality that even the fishing-boats may be 

 recognized. Lake Ontario is about seventy 

 miles wide opposite Rochester, yet the coast 

 of Canada has presented itself across that dis- 

 tance with distinctness. The images of ships 

 in the air occur frequently in all high latitudes, 

 because the angle of the sun is always low 

 there, and when the sea is calm the conditions 

 of reflection are nearly perfect. Capt. Scores- 

 by while there discovered the position of his 



FIG. 1. THE FATA MORGANA. 



the cross appearing in the air to Constantino, 

 the same symbol in like position distinctly 

 presented itself to priest and people, awing 

 the multitude into profound devotion. Sub- 

 sequent investigation showed that there was 

 in the grounds a material cross exactly similar 

 in its proportions to that which had appeared 

 in the sky. A church in St. Petersburg, stand- 

 ing in the center of an extensive sward, pre- 

 sented its image in the air in the same man- 

 ner ; but a thunder-storm had just passed over 

 and it was about four o'clock in the afternoon ; 

 so that the wet sward had the character of a 

 brilliant reflecting surface, and the low alti- 

 tude of the sun gave the best possible angle 

 for casting the image of the church into the 

 air. Under similar conditions the mirage is 

 occasionally seen over the Western prairies, 

 where horsemen or herds of buffalo furnish 



father's ship by seeing its image in the air. 

 When a breeze sprang up, he sailed in the di- 

 rection of where the phantom had been, and 

 found the reality. This was the first practical 

 use ever made of specters in the air, and yet 

 Sir David Brewster, who was the received 

 authority on optics of those days, misinter- 

 preted the causes of its production and thereby 

 delayed for many years its practical value. 



The shadows projected from the tops of Scot- 

 tish and those from the German mountains 

 differ only in so much as that the latter is cast 

 by the rising and the former by the setting 

 sun, which is referable to the conformation 

 of the surrounding mountains, leaving open the 

 path for the sun's rays at the proper time. 

 They are nothing more than ordinary shad- 

 ows, made apparent by being intercepted by a 

 cloud or fog-bank, and when this natural back- 



