Mountain Journeys 79 



by numerous expeditions made every year on lofty mountains. 

 Now at fairly moderate heights he had already felt symptoms, 

 which had attracted his attention. In the account of his ascent of 

 Buet, made July 13, 1778, in the company of Pictet, he gives l15 a 

 very clear indication of it: 



The rarity of the air, as soon as one passes the elevation of 

 1300 to 1400 fathoms above sea level, produces very strange effects 

 upon the body. 



One of these effects is that muscular strength is exhausted very 

 quickly. (Vol. I, p. 482.) .... 



Another effect of this thin air is the drowsiness it produces. As 

 soon as one has rested for a few moments at these great heights, 

 he feels his strength entirely restored, as I have said; even the 

 impression of the former fatigue seems wholly effaced; and yet in 

 a few moments one sees all who are not busy, falling asleep, in 

 spite of the wind, the cold, and the sun, and often in very uncomfort- 

 able positions. Of course fatigue, even on the plains, produces sleep; 

 but not so suddenly, especially when it seems to have entirely 

 disappeared, as it does on the mountains, as soon as one has rested 

 a few moments. 



These effects of the thinness of the air seemed to me quite 

 universal; some persons are less subject to it; the dwellers on the 

 Alps, for example, who are accustomed to living and working in 

 this thin air, seem less affected by it; but they do not entirely escape 

 its effect. The guides, who on the lower slopes of the mountains can 

 climb for hours at a time without stopping, have to pause to get their 

 breath every 100 or 200 steps, as soon as they are at an elevation of 

 1400 or 1500 fathoms, and as soon as they have halted for a few 

 moments, they too fall asleep with surprising promptness. One of 

 our guides, whom we had standing on the top of Buet with a parasol in 

 his hand so that the magnetometer might be in the shade while M. 

 Trembley observed it, kept falling asleep constantly in spite of the 

 efforts which we made and which he made himself to struggle 

 against this drowsiness. And on my first trip to Buet, Pierre Simon, 

 who had crept into a snow crevasse to shelter himself from a cold 

 north wind which distressed us greatly, went sound asleep there. 

 But there are constitutions which this rarity of the air affects still 

 more severely. One sees men, very sturdy elsewhere, consistently 

 attacked at a certain elevation by nausea, vomiting, and even fainting, 

 followed by an almost lethargic sleep. And all these symptoms cease 

 although fatigue continues as soon as they have reached a denser air 

 in the descent. 



Fortunately for the progress of physics, M. Pictet is not so 

 seriously affected by the thinness of the air; however, he is more 

 affected than the average man, for although he is very strong, very 

 nimble, and well trained in climbing mountains, he is always attacked 

 by a sort of distress, a. slight nausea, and an absolute loathing of 

 food, as soon as he reaches the elevation of 1400 fathoms above sea 

 level. As for me, I feel no effect other than being obliged to rest very 



