Symptoms of Decompression 669 



chilled to the point of death before being returned to normal 

 pressure. 



These facts, which I might have multiplied, serve to show that 

 outside the general rule are found numerous exceptions, which 

 explain the lack of agreement on this subject among observers on 

 mountains and aeronauts. We shall return to this point later. 



Finally, let us note that besides the rate, respiration is affected 

 in its rhythm; it becomes irregular, often dicrotic, sometimes 

 deeper, and I have seen it in dogs at very low pressures separated 

 into two parts: thoracic inspiration and then diaphragmatic in- 

 spiration. Moreover, every general movement is accompanied by 

 a sort of anhelation. All that agrees with what has been observed 

 in man. 



The lessening of the maximum of respiratory capacity was 

 shown by an experiment made upon myself, the details of which 

 will be given in Subchapter III. At normal pressure it was repre- 

 sented by the number 17.3, arbitrary value; at 430 mm. of pressure, 

 it had fallen to 11.8, and after a half-hour stay under pressures of 

 about 420 mm., it was only 9.9. 



2. Circulation. 



Besides the experiments reported above, I think I should give 

 the details of one which I made upon myself. 



Experiment CCXXX. July 29, the temperature being 23.5°, the 

 pressure 75.5 cm., I enter the large cylinder, and sit down there, 

 remaining very quiet. 



At 2:35, my pulse rate was 64, at normal pressure. 



At 2:45, pressure 72 cm.; pulse rate only 60; perhaps resting 

 alone was enough to cause this drop. 



At 2:55, pressure 63 cm.; pulse 63. 



At 3 o'clock, pressure 60 cm.; pulse 67. I am now forced, by the 

 expansion of the intestinal gases, to open my garments wide. 



At 3:08, pressure 55 cm.; pulse 67. I now rise and take two or 

 three steps in the cylinder; my pulse immediately rises to 80. 



I let the pressure slowly rise. 



At 3:15, pressure 62 cm.; pulse 63. 



At 3:24, pressure 72 cm.; pulse 60. 



At 3:28, return to normal pressure; pulse only 59. 



I leave the cylinder and walk rather rapidly in the laboratory; 

 my pulse rises only to 67. 



I have experienced no disagreeable sensations, except the tension 

 of intestinal gases, and a need of swallowing my saliva frequently to 

 clear the Eustachian tube. 



The experiments upon myself, whose details Subchapter III of 

 the present chapter will recount, give the same results. 



