216 Historical 



fore the air had hardly more than half of its usual density, we shall 

 understand that the lack of density had to be compensated by fre- 

 quency of inspirations. Now this frequency accelerated the movement 

 of the blood, all the more because the arteries were no longer com- 

 pressed from without by a pressure equal to what they usually ex- 

 perience; and so we all had fever. (Vol. IV, p. 147.) 



He returns a little later to this explanation and draws conclu- 

 sions from it. He likewise refutes the theory of Bouguer: 



2021. — Of all our organs, the one which is most affected by the 

 rarity of the air is that of respiration. We know that to maintain 

 life, especially that of warm-blooded animals, a specified quantity of 

 air must pass through their lungs in a given time. If then the air 

 they breathe is twice as rare, their inspirations must be twice as 

 frequent, so that the volume may compensate for the rarity. It is 

 this forced acceleration of respiration which is the cause of the fatigue 

 and the distress which one experiences at these great heights. For at 

 the same time that respiration accelerates, the circulation accelerates 

 also. I had often noticed this on lofty peaks, but I wished to make 

 an exact test of it on Mont Blanc; and so that the effect of the motion 

 of walking might not be confused with that of the rarity of the air, 

 I did not make my test until we had remained quiet or nearly quiet 

 for four hours on the summit of the mountain. Then the pulse rate 

 of Pierre Balmat was 98 per minute; that of Tetu, my servant, 112, 

 and mine, 100. At Chamounix, also after resting, the same men, in 

 the same order, had pulse rates of 49, 60, 72. 



While there, we were all in a state of fever which explains both 

 the thirst which tormented us and our aversion to wine, strong liquor, 

 and even all kinds of food . . . 



However, when we remained perfectly quiet, we had no definite 

 discomfort. And that is the fact which made Bouguer think that the 

 symptoms which one experiences in this air come only from fatigue, 

 for he agrees with me on all the data . . . 



It seems evident to me that in explaining these data, the learned 

 academician made a mistake, confusing the effects of the rarity of the 

 air with those of weariness. Weariness does not produce the effects 

 of the rarity of the air. Often, in my youth, when I returned from 

 some long mountain trip, I felt weary to the point of not being able 

 to stand up any longer; in the state which Homer expressed so ener- 

 getically by saying that the limbs are dissolved by fatigue, and yet I 

 felt no nausea or faintness, and I desired restoratives, far from feeling 

 a dislike for them. Moreover, although these academicians often ex- 

 perienced great fatigue in the course of their long and painful labors, 

 nevertheless, to ascend Pichincha, which is particularly mentioned, 

 they started from Quito, which is at an elevation of 1400 or 1500 

 fathoms, and they went still higher on horseback. They therefore had 

 only 300 or 400 fathoms to make on foot, which could hardly produce 

 a fatigue capable of causing the symptoms which Bouguer describes. 

 Therefore the same muscular movement which would have produced 

 only moderate weariness without any symptoms in a dense air pro- 



