380 TRAVELS A3I0NGST THE GREAT ANDES, chap. xix. 



when his method is adopted ; he ignores the influence of Time, and 

 argues as if the effect produced in a minute is similar to that 

 which would be caused in an hour, a day, or a week ; and he sets 

 an inordinate value upon the apparent checking of the rate of the 

 pulse, which in itself, apart from other considerations, is of little 

 moment. He assumes that the rate of the pulse is permanently 

 accelerated while experiencing low pressures, and bases his recom- 

 mendations upon that supposition. From the absence in his two 

 final experiments (the crown of his work) of all reference to the 

 effect of inhalation of oxygen upon respiration, and there being but 

 one solitary observation of the temperature of the body (at the end 

 of Exp. 257), one naturally enquires whether the rate of respira- 

 tion and the temperature of the body were observed ; and, if they 

 were, whether a satisfactory result was noted ? 



Professor Bert's attention, presumably, was first directed to 

 acceleration in the circulation upon reduction of pressure through 

 the frequent references which had been made to the subject by 

 aeronauts and mountain-travellers. De Saussure was amongst the 

 first to remark it on land,^ and Gay-Lussac and Biot in balloon.^ 



1 " Mais de tous nos organes, celui est le plus affecte par la rarete de Pair, c'est 

 celui de la respiration. On salt que pour entretenir la vie, sur-tout celle des animaux 

 a sang chaud, il faut qu'une quantite determine d'air traverse leurs poumons dans 

 un terns donne. Si done I'air qu'ils respirent est le double plus rare, il faudra que 

 leurs inspirations soient le double plus frequentes, afin que la rarete soit compensee 

 par le volume. C'est cette acceleration forcee de la respiration qui est la cause de la 

 fatigue et des angoisses que I'on eprouve a ces grandes hauteurs. Car en meme tems 

 que la respiration s'accelere, la circulation s'accelere aussi. Je m'en etois souvent 

 apperfu sur de hautes cimes, mais je voulois en faire une epreuve exacte sur le 

 Mont-Blanc ; et pour que Paction du mouvement du voyage ne put pas se confondre 

 avec celle de la rarete de Pair, je ne fis mon epreuve qu'apres que nous fumes restes 

 tranquilles, ou a peu pres tranquilles pendant 4 heures sur la cime de la montagne. 

 Alors le pouls de Pierre Balraat se trouva battre 98 pulsations par minute ; celui 

 de Tetu, mon domestique 112, et le mien 103. A Chamouni, egalement apres le 

 repos, les memes, dans le meme ordre battirent 49, 60, 72. Nous etions done tous 

 la dans un etat de flevre."— Fo^/a^'es dans les Alpes, % 2021, Vol. 4, 1796. 



'^ In 1804, in balloon, when no higher than 8600 feet, they observed that their 

 respective pulses rose from 62 to 80, and from 89 to 111. 



