300 SCIENTIFIC RECREATIONS. 



there was a difference of 67 in the temperature on the earth, for at 

 the maximum height attained the thermometer stood at I4'9. 



But the most important fact ascertained, and one which set many 

 theories at rest, was the composition of the atmosphere in those high 

 altitudes. We mentioned that Gay-Lussac took up two empty flasks from 

 which the air had been taken. The vacuum was almost perfect When 

 the aeronaut had reached 21,460 feet he opened one flask, and it was 

 quickly filled ; he secured it carefully ; and when at his highest point, four 

 miles and a half above the sea-level, he opened the other flask. The 

 barometer stood at 12.95 inches, and the cold was very great. The voyager 

 felt benumbed, and experienced difficulty of breathing ; his throat was 

 parched and dry. So Lussac determined to return, he could go no higher. 

 He dropped gently near Rouen, and soon reached Paris. As soon as 

 possible the air in the flasks was submitted to very delicate tests, and to the 

 .satisfaction of the scientists engaged it was found to be in exactly the same 

 proportions as that collected near the earth two hundred and fifteen parts 

 of oxygen to every thousand of atmospheric air. 



Messrs. Banal and Bixio, in 1850, also made some observations, and 

 found the temperature very variable. At 23,000 feet they found the 

 thermometer at minus 38*2 Fahr., which was much below the cold 

 'experienced by Gay-Lussac. We may still conclude that the various 

 currents of the atmosphere cause considerable variation, and that it is 

 impossible to lay down anything respecting the degrees of heat and cold 

 likely to be found at certain elevations. We quote Arago's observations 

 upon this ascent : 



" This discovery " (the ice particles found in the air) " explains how 

 these minute crystals may become the nucleus of large hailstones, for they 

 may condense round them the aqueous vapour contained in the portion of 

 the atmosphere where they exist. They go far to prove the truth of 

 Mariotte's theory, according to which these crystals of ice suspended in the 

 air are the cause of parahelia or mock-suns and mock-moons. Moreover, 

 the great extent of so cold a cloud explains very satisfactorily the sudden 

 changes of temperature which occur in our climates.*' 



M. Flammarion gives in his "Voyages" some very interesting and 

 amusing particulars, as well as many valuable scientific observations. 

 During one ascent he remarked that the shadow of the balloon was white, 

 and at another time dark. When white the surface upon which it fell 

 looked more luminous than any other part of the country ! The phe- 

 nomenon was an anthelion. The absolute silence impressed the voyager 

 very much. He adds, "The silence was so oppressive that we cannot help 

 asking ourselves are we still alive ! We appear to appertain no longer to 

 the world below." M. Flammarion's observations on the colour of what we 

 term the sky are worth quoting not because they are novel, but because 

 they put so very clearly before us the appearance we call the " blue vault." 

 He says, speaking of the non-existence of the " celestial vault," " The air 



