1878.] the Function of Respiration at Various Altitudes. 301 



them nearly but not quite the same. An increase in the amount of 

 carbonic acid evolved at places increasing in altitude was attended 

 with an actual decrease of the volume of air expired also reduced. 

 This result again agrees with that obtained by Mr. Mermod. It applies 

 in my case to greater altitudes, attended with differences of tempera- 

 tures at the various stations ; while, as already stated, the temperature 

 of the air was the same at Mr. Mermod's two stations. As the amount 

 of carbonic acid expired is more at the higher stations than at the 

 lowest, and the volume of air breathed (reduced) less at the higher 

 stations, it must follow that the proportion of carbonic acid expired 

 will be greater at the higher than at the lowest station ; we find 

 accordingly that the mean for the high stations yields 4' 9 per cent, of 

 carbonic acid in the air expired, while the experiments at the lowest 

 station give 4*1 per cent. 



From observations made with and without the face-piece, it follows 

 that I breathed into the open air slower, and apparently deeper, 

 through the mask than without it. This accounts for the small number 

 of expirations I noted per minute in all my experiments. Relatively, 

 however, the results obtained on this point may be accepted, as the 

 breathing was carried on always in the same way while sitting and 

 walking respectively. We find an increase in the frequency of respira- 

 tion from an altitude of 8,115 feet to that of 13,685 feet, but hardly 

 any such increase between the altitudes of 1,230 feet and 8,115 feet. 

 This greater number of respirations per minute between the St. Bernard 

 and Breithorn was not observed to progress proportionally with rising 

 altitudes from 8,115 feet, as will be seen in the table, and there must 

 have been some other cause besides increased elevation to account for 

 it. Mr. Mermod found no difference in the frequency of respiration 

 between 466 feet and 3,609 feet ; and here, again, for low stations I 

 agree with him ; but I cannot follow him in concluding that, therefore, 

 the phenomenon is not altered at greater altitudes. 



The volume of air reduced, exhaled per respiration, varied at the 

 several stations, but followed no regular change relatively to altitude ; 

 it ranged from 510 cub. centims. at St. Theodule, to 760 cub. centims. 

 at the St. Bernard. 



Experiments made while walking on Level Ground, or ascending. 



In every one of these experiments I walked for a short time, say 

 two or three minutes, or longer, before commencing to collect the air 

 expired. They are fewer in number than those made sitting, and less 

 satisfactory, as it is impossible to depend upon the degree of muscular 

 exertion being the same in comparative experiments while in the act of 

 walking or climbing. 



X 2 



