1878.] the Function of Respiration at Various Altitudes. 297 



the mean altitude of which was 10,292 feet, the maxirtinm carbonic 

 acid expired is during the first hour after a meal, and the minimum 

 from four to six hours after eating. There is a slight rise during the 

 fourth hour after a meal, by 4 mgms. only, probably due to a cause 

 independent of food. 



At the low station, 1,230 feet above the sea, the maximum carbonic 

 acid is expired the second hour after a meal. There is a slight rise also 

 by 4 mgms. between the fourth and sixth hour after a meal, probably 

 owing likewise to some cause independent of food. 



The whole of my experiments are not included in the means of this 

 table, as many of them bore no record of the time they were made at, 

 with reference to the last meal taken. I must also add, that the tem- 

 perature was only noted occasionally during the day while the experi- 

 ments were being made, and not at each experiment, as there was 

 frequently no marked change of temperature between one experiment 

 and another. 



I only wish to draw general conclusions from this table, which cer- 

 tainly shows that the ingestion of food increases temporarily the 

 amount of carbonic acid expired, a fact which has been fully proved by 

 the experiments of Edward Smith ;* I find that the greatest quantity 

 of carbonic acid is expired during the first or second hour after a meal, 

 according to E. Smith this occurs in from one and a-half to two and 

 a-half hours after a meal. 



In order to neutralize the influence of food, my experiments were 

 made at all times of the day between breakfast and a late dinner, with 

 but two exceptions which only reduce the means by 2 mgms. for the 

 carbonic acid expired at one station, and 4 mgms. at the other. Hence 

 it cannot be considered, in my estimation of the influence of altitude 

 on respiration, that the food taken exerted any marked influence. I 

 must add, however, that I took, on the whole, less food at the two 

 highest stations — the St. Theodule Pass and Breithorn — than at the 

 other places. 



The following table shows the mean results obtained from the experi- 

 ments made at the five different stations in the sitting posture : — 



* < ; Phil. Trans.," 1839. 



