ig6 Account of the Aerial Voyage 



east wind towards the land side; but when it rose to a 

 greater height it appeared to change its direction, and pro- 

 ceed straight towards the sea. A^cverthelcss wc did not sus- 

 pend our aerial vovage ; but, having put into the car every 

 nccessarv, placed ourselves in it. But as one of the most 

 important experiments in my opinion was to collect air in 

 the exhausted flasks which I took with me, at diflcrent 

 heishts, at each tall of an inch in the barometer, which 

 rendered a gradual and slow ascent of the balhjon necessary, 

 we added so much ballast to that already taken in, after we 

 h;ul seated ourselves in the car, that the balloon was not 

 able to raise us up. About fifteen minutes after seven, 

 when the barometer stood at 30 inches English, and the 

 thermometer indicated I9 degrees of heat, we threw out a 

 handful of the ballast, which consisted of sand. The bal- 

 loon innncdiately begin very slowly to rise, but sunk down 

 aoain over the Neva after it had attained to a considerable 

 height. The' reason of this, in all probability, was, that 

 the balloon had been surrounded by a very warm atmo- 

 sphere at the earth, by which means the gas in it occupied 

 more space, and was the cause of its greater lightness j but 

 at a height where the air, particularly over the Neva, was 

 colder, where the matter of heat was absorbed by the wa- 

 terv vapours which arose, and where the hydrogen gas, on 

 cooling, contracted, by which the balloon became smaller 

 and heavier in regard to the more rarified air, it must ne- 

 cessarilv lose some of its power to ascend, and consequently 

 fall a little. But after a small quantity of ballast was thrown 

 out, the balloon again rose. The telescope, fixed in the 

 bottom of the car, clearly showed me the places over which 

 we were. The balloon, according to appearance, took its 

 direction towards the land side. About 31 miraites after 

 seven, when the barometer had fallen to ^9 inches, and the 

 thermometer indicated 18 degrees of heat, I iilled the first 

 flask with air; the second I filled at 37 minutes past seven, 

 the barometer being at 28 inches, and the thermometer at 

 17 degrees of heat. I filled the third flask at 42 minutes 

 jiast seven, at which time the barometer stood at 27 inches, 

 and the the'-momeler had fallen to 15 degrees. At this 

 time, or at this height, I experienced a heaviness in my 

 ears, i)nt in conversing I heard as well as before. During 

 the continuation of our voyage the balloon turned round 

 several times. This always took place gradually, slowlv, 

 and alnio-ii im|>crceptiblv. The direct motion of the bal- 

 loon during a perfect calm, and when there is no apparent 

 motion in the air, is not perceptible. In consequence of 



the 



