CELEBRATED ASCENTS. 



301 



reflects the blue rays of the solar spectrum from every side. The white 

 light of the sun contains every colour, and the air allows all tints to pass 

 through it except the blue. This causes us to suppose the atmosphere is 

 blue. But the air has no such colour, and the tint in question is merely 

 owing to the reflection of light. Planetary space is absolutely black ; the 

 higher we rise the thinner the layer of atmosphere that separates us from it, 

 and the darker the sky appears." 



Some beautiful effects may be witnessed at night from a balloon, and 

 considering the few accidents there have been in proportion to the number of 

 ascents, we do not wonder at balloon voyages being undertaken for mere 

 pleasure. When science has to be advanced there can be no objection made,. 



Fig. 298. The "Eagle" of M. Godard. 



for then experience goes hand-in-hand with caution. It is only the ignorant 

 who are rash; the student of Nature learns to respect her, and to attend to her 

 admonitions and warnings in time. The details of the ascents of famous- 

 aeronauts give us a great deal of pleasant and profitable reading. The 

 phenomena of the sky and clouds, and of the heavens, are all studied with 

 great advantage from a balloon, or " aerostat," as it is the fashion to call it. 

 The grand phenomena of " Ulloa's circles," or anthelia, which represent the 

 balloon in air, and surrounded by a kind of glory, or aureola, like those 

 represented behind saintly heads, appear, as the name denotes, opposite to- 

 the sun. 



The various experiments made to ascertain the intensity of sounds have 

 resulted in the conclusion that they can be heard at great distances. For 

 instance, the steam whistle is distinctly audible 1 0,000 feet up in the 



