'280 AEROSTATIC VOYAGE. 



to attract the electricity at 50 and at 100 metres below me, 

 and I could not make any ufe of it. It will be feen that we 

 had avoided every thing which could influence our needles ; 

 and even our anchor, although fufpended 50 metres below 

 the boat, was of wood armed with copper. 



This is not the place to mention the precautions which M. 

 Come" had taken, that this new afcent might be free from 

 danger- but it is to be wifhed that he would himfelf publifh 

 ■what a long and enlightened experience has taught him on 

 this fubjeft. lor ourfelves, we owe him a great tribute of 

 gratitude for his trouble and the intereft he has taken in our 

 voyages ; and we are bound to acknowledge, that if they 

 have been lb fortunate, we are indebted for it (o his provident 

 cares. 



Departure All our inftruments being ready, my departure was fixed 



for the 29th Fruclidor : In fact, on that day I afcended from 

 the Confervatory of the Arts and Manufactures, at 9 h 40', the 

 barometer being at 7b. 525 centimetres, the hygrometer at 



State of the at- 57. 5 P , and the thermometer at 27.75 p . M. Bouvard, who 



™£ CtC ° n tlC makes meteorological obfervations daily at the Obfervatory 

 of Paris, judged the atmosphere to be greatly charged with 

 vapour, but without clouds. In fact, I had fcarcely rifen 

 1000 metres when I perceived a light vapour diffufed through 

 all the atmofphere, which rendered the fight of remote objects 

 confufed. 



Firft eip-riment Arrived at the height of 3032 metres (9929. S F.), I began 



o.'thecfciHa- to make the horizontal needle ofcillate, and this time I ob- 

 tions of the ho- 

 rizontal needle, tained 20 ofcillations in 83'', while on the earth, and in other 



refpects in the fame circumftances, it required 81. 33" to make 



the fame number*. Although my balloon was affected with 



the rotatory motion we had perceived in our firft experiment, 



^•- the rapidity of the motion of our needle permitted me to 



count 20, 30, and even 40 ofcillations. 



Inclination of At the height of 3853 metres (12651.365 F.), I found the 



the needle at a variation of my needle, taking the mean of the amplitude 



12^51. ^5 feet, of its ofcillations, was fenfibly 31 Q , as on the earth. It re- 



the (a:ne as on 



* Although I have here indicated hundredth parts of a fecond, 

 I am aware that I cannot cbfeive fueb fmnll fractions ; but I ob- 

 tained them by divifions, becaufe on the earth I generally made 

 CO rfcillations, which required 126.5". 



2 quired 



