THE PHYSIOLOGY OF THE AVIATOR 103 



In this ascent the balloon continued to rise until a mini- 

 mum pressure, registered automatically, of 263 mm. was 

 reached. When Tissandier recovered consciousness Sivel 

 and Croce-Spinelli were dead. They were all provided 

 with oxygen, ready to breath; but all were paralyzed be- 

 fore they could raise the tubes to their lips. Tissandier's 

 notes are characteristic of the mental condition when 

 oxygen-want is becoming dangerous. 



In marked contrast to this condition is that of men who, 

 gradually ascending into the mountains, day by day be- 

 come acclimatized without realizing that any change has 

 occurred. The record for the greatest altitude attained 

 by mountaineers is held by the Duke of Abruzzi and his 

 party in the Himalayas. They reached an altitude of 

 24,000 feet, where the atmospheric pressure is only two- 

 fifths of that at sea level, or practically the same as that 

 at which Tissandier's companions lost consciousness. At 

 this tremendous altitude the Duke and his Swiss guides 

 were not only free from discomfort, but were able to 

 perform the exertion of cutting steps in ice and climb- 

 ing. Dr. Filippi, the physician who accompanied them, 

 in discussing this matter says that the fact of their im- 

 munity admits of but one interpretation : 



Rarefaction of the air under ordinary conditions 

 of the high mountains to the limits reached by man at 

 the present d'ay (307 mm.) does not produce moun- 

 tain sickness. 3 



In this statement, however, he is certainly mistaken, 

 for the observations of others show conclusively that the 

 sudden exposure of unacclimatized men to an altitude 

 considerably less than that reached by this party would 

 either produce collapse like that of Tissandier 's compan- 

 ions, or if long continued would result in mountain sick- 



3 Quoted from Douglas, Haldane, Henderson and Schneider, 

 Physiological Observations on Pikes Peak, Phil. Trans., 1913, B. 

 203, p. 310. 



