performed hj Messrs. Guy-Lussac and Blot. 373 



3 lines; Reaumur's thermometer at 13*2°, and the hygro- 

 meter at 80*8°; consequently very near to the greatest de- 

 gree of humidity. M. Conte, whom the minister of the 

 interior entrusted with the preparations, had taken every pos- 

 sible care to render our excursion successful ; which was 

 in reality the case. 



The first moments after our ascent were not employed, 

 we confess, in making experiments. We could not help 

 admiring the beauty of the surrounding spectacle. Our 

 slow and gradual ascent produced on us that impression of 

 confidence which one always experiences when abandoned 

 to one's self with secure means. We could still hear the 

 encouraging shouts of the spectators : but we had no need 

 Of them ; we were perfectly collected, and without the least 

 uneasiness. We enter into these details only to show that 

 some reliance may be placed on our observations. 



We soon reached the clouds. They were like light fogs, 

 which occasioned only a weak sensation of humidity. Our 

 balloon being entirely distended, we opened the valve to 

 let out the gas, and at the same time threw out ballast that 

 we might ascend higher. We now found ourselves above 

 the clouds, and we did not enter them again but in de- 

 scending. 



These clouds, when seen from above, appeared to us 

 blueish, as when viewed from the surface of the earth. 

 They were all exactly at the same elevation; and their upper 

 surface, full of small eminences, and undulating, presented 

 to us the aspect of a plain covered with snow. 



We were then at the height of about two thousand 

 metres*. We tried to make our needle oscillate; but we 

 soon found that the balloon had a very slow rotary motion, 

 which made the position of the car^ in regard to the direc- 

 tion of the needle, continually vary, and prevented us from 

 observing the point where the oscillations ended. The mag- 

 netic property, however, was not destroyed ; for, on pre- 



* We calculated these heights from observations of the barometer and 

 thermometer made in the balloon, and compared with those made by 

 M. liouvard at the observatory. We employed the formula of Laplace 

 with the corrected co-efficients which he adopted, and which M. Ra- 

 rnond deduced from a great number of trigonometrical measurements 

 inade with great care. Our thermometer was filled with spirit of wine ; 

 the scale was divided into ioo parts, and it was secured from the action 

 of the sun by a white handkerchief folded double, which was wrapped 

 round it, but in such a manner as not to be in contact with it. We took 

 every necessary precaution in the calculation, that we might not give to 

 our heights too great values j and they were rather too small than too 

 great. 



Vol. 19. No, 76, Sept, 1804. C c senling 



