1879.] Various Altitudes on the Island and Peak of Tenerife. 519 



portions were practically the same for both of us. The relations are 

 as follows : — 



Self J Air expired. ..... 



1 Carbonic acid expired. . 



u F e \ Carbonic acid expired 



Sitting. 



Rocking-board. 



Eelations. 



5- 36 litres 

 0-469 grm. 



6- 72 litres 

 603 grm. 



11-56 litres 

 1-011 grms. 



13 95 litres 

 1-269 grms. 



1 : 216 

 1 : 216 

 1 : 2-07 

 1 : 2-10 



As to the frequency of the respiration, while at work on the rocking- 

 boards, it was the greatest with me at the highest station, and with 

 the guide at the intermediate station ; in both cases it was the lowest 

 at the seaside. The mean frequency amounted, in my case, to 12'4 

 per minute against 10*2 sitting, giving a relation of 1*22 ; or for 

 1 respiration (expiration) sitting, I took l - 22 respiration on the 

 tread-board. "With the guide, the corresponding figures were 11 "0 

 against 9" 7, and the relation 1*13; so that for 1 respiration sitting, 

 the guide took 1*13 respiration on the tread-board. His breathing 

 while taking muscular exercise was, therefore, relatively rather slower 

 than mine had been under similar circumstances. 



11. The results obtained from the determination of the water expired, 

 or evaporated from the lungs and air-passages, show distinctly that 

 the moisture exhaled increases as a person rises above the sea. On 

 the Island of Teneriffe, where the temperature in the shade is com- 

 paratively high, even at great altitudes, there is a tendency to the 

 degree of evaporation being in an inverse ratio to the atmospheric 

 pressure. 



It is very obvious that this increased evaporation as altitude increased 

 must have caused a corresponding loss of heat, or cooling of the 

 lungs and air-passages ; I felt this very much at night, when the 

 temperature of the air frequently fell below freezing outside my tent. 

 Of course, no number of blankets on our beds could check that source 

 of cold. 



The amount of water evaporated from my lungs and air-passages 

 during twelve hours of daytime, calculated from the above data, 

 would be — 



At Alta Yista , . . . 226'1 grms. 

 At Guajara . . . . . . 177*8 „ 



At Puerto (seaside). . . . 131' 7 ,, 



The correction to be applied from the moisture present in the air 

 breathed increased, of course, very much at the seaside, where it 

 formed a considerable proportion of the moisture actually present in 

 the air expired. 



