SI Aerial ^avigafiotti 



At the height of 3;10'? metres, or 2002 toises, he found t\-,6 

 inclination of the needle the same as at the surfaee of the 

 earth. The duration of the oscillations of a horizontal 

 needle, mdde with great care by that able artist. Fcrtin, 

 magnetised by Coulomb ajid suspended by a silk thread, 

 were also the same. M. Gay-Lussac never fotind any sen- 

 sible difference in their duration. \Vhei\ he reached the 

 height of 667J metres, or 3425 toises, he opened two 

 gbss balloons which had been exhausted at the earth, and 

 which had preserved a coriipletc vacuum. The air entered 

 into them with a hissing noise; and when thev were filled 

 he clo-ed them. He continued to rise to the height of 

 7017 metres,- or 3600 toisxs; his barometer was then 12 in. 

 r70 Hn. and his therniometer in the shade marked 

 j7t decrees below the temperature of melting ice. — • 

 Thia lieitiht, the greatest to which any person ever as- 

 cended, surpasses by 600 metres the summit of Chim- 

 borar-o in Pera, t\\". highest mountain known on the earth. 

 IVl. Gav-Lussac still however saw clouds above him, but 

 which appeared to be at a great elevation. His pulse was 

 accelerated ; and the number of pulsations, which at the 

 earth was only C2, imncased to 95^ Hrs respiration was a- 

 littlc confined ; but he thinks he could have risen to the 

 heifrht of SOOO me; res, withcnU experiencing much incon- 

 Vcnicircc, liad he not been so imprudent as to throw out 

 before, the ballast Vi'hich would have been necessary to 

 moderate his rtsccnf. He therefore descended slowly, and 

 with those precautions which his first ascent had shown to 

 be necessary. At 4.T minutes past three he reached the 

 earth, without the slightest aci^ident,- six leagues to the 

 north of lioucn, at the small village of Saint-Gourgon ;" 

 the inhabitants of which assembled en seeing his balloon, 

 ifrave him every assistance, and treated him with the utmost 

 hospitality. 



On his return to Paris, his first care was to analyse the' 

 air he had collected in his ascent. One of his balloons being 

 opened niider water became half filled with it ; which proves 

 that no foreign air had entered it. On comparing the air 

 of this bdloon with that collected at the surface of the 

 earth, he ascertained by several vei'y exact eudiometric pro- 

 cesses, that the proportions of oxygen and azot in the two 

 airs were perfectly ec[in). 



'j'his interesting ncri;il voyage has therefore confirmed 

 two iiuportant points in natural philosophy ; namely, 1st, 

 'i'hat the ma<inetic force experiences no sensible variation,. 

 'citWr in its hiclination or its intcivsilv, from the surface 



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