Hijlorj ofjjlronomj'for the Yt:ar I799r 109 



rofe to the height of 250 toifes, and advanced at llic rate ot 

 fix leagues per hour. The dlredkion of the clouds, which £ 

 had examined before I fet out, was, on the contraryj towards 

 the weft: : thus I experienced, that when a local caufe impels 

 the lower part of the atmofpherc towards the weft:, that above 

 takes its place, and proceeds towards the ea ft. Of tlie two 

 balloons which I fent oft' before nie for the fake of trial, one 

 rofe to the height of 300 toifes, and direfted its courfc to- 

 wards Monfortj the other rofe to about the height of 600 

 toifes, and proceeded towards Rambouillet, which made fix 

 degrees of ditTerence. Thus, in 300 toifes the wind changed 

 fix degrees. By rifing, therefore, more or lefs, we ftiall one 

 day be able to vary our diredVion. The inclined planes of 

 C. Tetu Brefti, at Bellevue, afford us the means of varying 

 thefe dire6lions much more; and I hope that a proof of it 

 will be feen next fummer. 



A large balloon of nine feet, which was let off next niorn- 

 ing, rofe nuuh higher, and fell at Coucy, 23 leagues to the 

 '^lorth-eaft of Paris, having proceeded at the rate of eight 

 leagues per hour. It directed itfelf towards Maeftricht and 

 Ruremonde, while the clouds were proceeding in the direc- 

 tion of Joinville and Conftance towards the fouth-weft'. 

 Between the two direelions one n)Ig-iit have chofen for every 

 part of Germany. Thus, the project which I had announced 

 of going to Gotha was not, chimerical, as aflerted ; nothing 

 would have been necefl^ary but to choofc the height. The 

 vtlocitv of eight leagues p>a- hour was indicated alfo bv the 

 excurfion of Garnerin on the 28th of Thermidor, vear 6, who 

 went from Hoihi to Chalons in four hours. Twenty-four 

 hours, therefore, wovdd have been fufilcieiit to go to Gotha, 

 which was the term of my defires and my hopes. 



My aiiroftatic globe turned fix times, which flicwcd, that 

 in a current of air of twenty feet in height, there is a fenfible 

 difference of ibrce and velocity; but probably by rifing much 

 higher, I ftiould have found more regularity. 



I faw alfo, by the agitation of my barometer, that the fla- 



bility of the boat was not fufficicntly conftant to enable me 



to obferve it with my glalTcs; but at a greater height I fnould, 



wiiliuut doubt, have found more ftability: befidcs, as ou 



^ board 



