338 Historical 



peculiar explanations. Truthworthy, even eminent men have not 

 escaped this need of seeking elsewhere than in the effect of dimin- 

 ished pressure the cause of the distress experienced. 



Certain persons believed that they had found this cause in a 

 special weakening of the air or, to speak more exactly, in its 

 diminished oxygen content. That was the opinion of von Hum- 

 boldt (page 30), who said that he found only 20% of oxygen on 

 Chimborazo, and attributed a great effect to this difference. 



M. Boussingault, struck by the fact that mountain sickness 

 hardly ever occurs until perpetual snow has been reached, took 

 up an old idea of de Saussure, who had maintained that the air 

 released from the pores of the snow contains less oxygen than free 

 air; he made an analysis which gave only 16% of oxygen, and then 

 he attributed the suffocation which he had experienced to this 

 foul air. freed by the action of the solar rays (page 227) . By this 

 reckoning, one should experience mountain sickness on plains 

 covered with snow, in a fine January sun. Other travellers (page 

 294), without other objection, accepted this hypothesis, which the 

 celebrated chemist himself finally admitted was mistaken. 



Fatigue, cold. These are two causes frequently hailed, not as 

 adjuvants, which would be correct, but as the principal or. even 

 the sole cause. It is the warhorse of those who deny mountain 

 sickness: "We can assert," says one of them, "that these are the 

 same sensations experienced by ordinary travellers when they 

 approach the summit of any mountain" (page 231). "What proves 

 indisputably that these symptoms are due to fatigue," says 

 Bouguer, "is that no one was ever affected by them when he was 

 on horseback, or when he had once reached the summit, where 

 the air, however, was still thinner" (page 208) . 



We must admit that at first glance and for slight symptoms 

 confusion is possible. Hasty respiration, dyspnea, circulatory accel- 

 eration, palpitations, even vertigo, and heaviness of the limbs are 

 the result of any exercise which is somewhat tiring and prolonged. 

 But we need only glance at the numerous data reported above to 

 find in them the proof that there really is a special influence in 

 lofty places: the symptoms appear, as we have seen, even during 

 rest and sleep. Moreover, Acosta had very early refuted these 

 errors (page 24), as did de Saussure (pages 213, 216). 



Yet it is still fatigue, though of a special type, which Rey 

 invokes (page 232). M. Lepileur's ideas (page 237) are evi- 

 dently of the same sort; this learned physician in his explanation 

 of the fatigue gives overwhelming importance to "the congestion 



