498 Dr. W. Marcet on the Function of Respiration at [Apr. 24, 



IV. ;< A Summary of an Inquiry into the Function of Respiration 

 at Various Altitudes on the Island and Peak of Teneriffe." 

 By William Marcet, M.D., F.R.S. Received March 31, 

 1879. 



On the 19th March of last year, I presented to the Royal Society a 

 short summary of an inquiry on the function of respiration at various 

 altitudes in the Alps. The principal result obtained was that a greater 

 quantity of carbonic acid was formed in the body and exhaled at the 

 higher than at the lower stations. Thus, after experimenting on a 

 spot near the Lake of Geneva, at an altitude of 1,230 feet, and at the 

 summit of the Breithorn, at an altitude of 13,688 feet, there was 

 found to be an excess of 15 per cent, for the carbonic acid expired at 

 the highest station. I had come to the conclusion that the increased 

 formation of carbonic acid in the body at certain altitudes in the 

 Alps appeared necessary, as a means of resisting the influence of cold 

 which is occasionally very great in high Alpine regions. 



The question which now offered itself for inquiry was whether, on 

 rising to a considerable altitude above the sea in a warm climate, 

 there would be, as I had found in the Alps, an increase of the carbonic 

 acid expired. After some consideration, the Peak of Teneriffe, in 

 north latitude 28°, was selected as the place best calculated for investi- 

 gating the subject. The advantages of this site were manifold. First, 

 a mean temperature in the day time, which proved to be not lower 

 than 64° in the shade, could be secured at an altitude above 10,000 

 feet; next as the mountain rose from the sea, various stations, 

 beginning at the seaside, might be selected ; then fine weather could 

 be relied upon in June and July, on the Island of Teneriffe ; finally, 

 the spot was situated at an accessible distance from England. 



It took me three weeks to collect the necessary instruments, among 

 which was a wooden shed, taking to pieces and made to pack in a 

 comparatively small space. It consisted of six deal boards constructed 

 so as to fit side by side with overlaping edges ; when mounted, they 

 formed a flat square roof. The four corners of this roof were sup- 

 ported by four poles held upright by tent ropes and pegs ;. broad 

 strips of canvas were nailed to two opposite sides of the roof and 

 spread out, being held in position by strings and pegs. The boards 

 covered a square of 6 feet on each side and the sheltered area was 

 much increased by the canvas. The shed was placed lengthways as 

 nearly as possible in the direction of the course of the sun, and by this 

 means we could work all day long in the shade, a necessary condition 

 for the success of the inquiry. 



My experimental baggage included two large baskets holding about 

 150 bottles of a capacity of rather more than 100 cub. centims. each, 



