200 Aerial Voyage undertaken at Peterslurgh. 



In the mean time Mr. Robertson gradually suffered the gas 

 to escape, and the balloon desconded slowly, and touched 

 the earth so Sf)ftly, that we did not experience the least 

 shock ; though the contrary is for the most part the case 

 when balloons are suffered to descend, and in consequence 

 of the violence with which they touch the earth great danger 

 is experienced. We descended safe to the earth, at 4,5 mi- 

 nutes past ten, on the estate of counsellor Deniidof, in a 

 field almost opposite to his house; and his boors and servants 

 assisted us to arrange and pack up the balloon. By the 

 bundle being dragged on the earth, the oreater part of the 

 instruijients were spoilt. Of the eight flasks filled with air 

 brouoht from the atmosphere, four only were fit for being 

 .subjected to experirnent; namely, numbers 1, 4, 6, and 7 ; 

 but I did not venture to examine them. In the rest, after 

 the necks were inverted under the quicksilver, none of the 

 latter ascended ; from which it appears that they were not 

 sufficiently stopped. 



The aerial voyage, set on foot by the academy, being thus 

 ended, though I made experiments on the electric matter 

 and the magnet, filled the flasks with air at different heights, 

 made observations on myself and on the direction of the bal- 

 loon during my voyage, I must confess that I ani not able 

 from these first experiments to draw any certain conclu- 

 sions ; because the small height to which the ballopn rose, 

 contrary to my wish ; the consuinption of the ballast by the 

 balloon's twice rising ; the lateness of the time; the short 

 duration of the voyage, and other circumstances, were the 

 p incipal causes which prevented me from making all the 

 experiments appointed by the academy, and from making 

 them with that accuracy which is necessary to deduce froni 

 them any well founded physical conclusions. 



But I hope I shall have an opportunity of repeating all 

 these expernnents with greater accuracy. For, since I have 

 experienced the nature of a voyage of this kind, I have no 

 doubt that I shall be able to direct a balloon; to make ob- 

 servations in general on the filling of one, which may be 

 of great use to the aeronaut during his voyage in the air; 

 and to make some improvement in the method of throwing 

 out ballast, or lightening the balloon ; and in making expe- 

 riments. But on this subject I shall have the honour of 

 giving the academy further information. 



XXXV. A 



