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XXXIV. An Account of the Aerial Voyage undertaken at 

 Petershurgh on the 30th of January 1804. Read before 

 the Academy of Sciences by the Academician Sacharof . 



xiiTHERTO aerial voyages have been undertaken merely 

 for the gratification of the public. Since the invention of 

 balloons, no learned society, or man of science, has under- 

 taken such excursions in order to make physical obser\'a- 

 tions. Men eminent for their scientific acquirements sel- 

 dom embark in them merely on account of the advantage 

 resulting from them. They always represent them as more 

 dangerous than they are in reality, in order to excite greater 

 admiration of their intrepidity, and by these easy means to 

 prevent others from acquiring the same celebrity. The Impe- 

 rial Academy of Sciences at Peiersburgh, considering the^ 

 advantages which might result from an aerial excursion of 

 this kind, resolved to cause one to be undertaken for the 

 purpose of making scientific researches. The principal 

 object of this voyage was to ascertain exactly the physical 

 state of the atmosphere, and the component parts of it, at 

 different determinate heights. The academy had entertained 

 an opinion, that the experiments made by De Luc, Saus- 

 sure, Humboldt and others, on mountains, must give other 

 results than those made in the open air ; that this difference 

 might arise from the attraction of the earth and the decom- 

 position of organized bodies ; and that by these means the 

 law which accurately determines the height of the atmo- 

 sphere might perhaps be found. The academy afterwards 

 requested the academician Lowitz, who undertook to make 

 the proposed experiments in the atmosphere, to confer on 

 this subject with professor Robertson. Mr. Robertson de- 

 clared he would consider it as a particular honour to be of 

 anv service to the academy in this respect; that he would 

 with pleasure accompany this philosopher; and that the 

 balloon he had constructed at Peter^burgh was at the ser- 

 vice of the academy for that purpose: he only requested 

 that the academy would defray the expen^ie which would 

 arise from filhng'the balloon with hydrogen gas. The aca- 

 demy thanked Mr. Robertson for the zeal he had rnanifested^ 

 and set apart a certain sum for carrying this aerial voyage 

 into effect. While preparations were making for this ex- 

 cursion, and while the aeronauts were waituig for a favoura- 

 ble wind, Mr. Lowitz fell sick, and the president, Nicolai 

 Nikolayevitseh Novossilzof, proposed to me to supply his 

 place. As this proposal showed that particular confidence 

 \\A. 21. No. 83. Ayril 1805. N wa» 



