158 Historical 



July 10, crossing of the pass of Chang-La, from the basin of 

 the Indus to that of Shyok, one of its tributaries, at 18,000 feet 

 (5485 meters); little snow: 



It was the first time that almost everyone in camp suffered from 

 the rarity of the air. The following observations, made after a half- 

 hour's rest at the summit, may seem interesting: 



Mercury barometer 15.73. Thermometer 61 °F. Water boiling at 

 181° F. 



I walked to the summit 



M. Forsyth, who was on horseback 



M. Shaw, who was on horseback 



Mullik Kutub Deen, of Punjab, on horseback 



A Hindu of Punjab, on foot 



A Thibetan, on foot 



Several travellers told me that they and their companions 

 had suffered more while crossing this pass than on others which were 

 higher. We camped for the night near a little lake of sweet water, at 

 300 feet below the summit of the pass. The painful symptoms caused 

 by the rarity of the air did not disappear until the next day, when 

 we were at a much lower altitude. As for me, even at 19,600 feet, I 

 have never felt great discomfort; mine amounted only to a certain 

 shortness of breath after any exercise, and awakening during the night 

 with a feeling of suffocation which disappeared usually after a few 

 deep inspirations. But in several of our men the symptoms were very 

 serious, and even alarming sometimes. They consisted of intense 

 headaches, with great prostration of body and mind, constant nausea, 

 and such an irritation of the stomach that even a spoonful of water 

 was not tolerated. A great irritability of disposition was another 

 marked symptom; in some cases the lips became blue; in M. Shaw, 

 a clinical thermometer showed a temperature which had fallen 1 or 2 

 degrees in comparison with that of the preceding days. Having with 

 me a certain quantity of chlorate of potash, I gave a strong solution 

 of it to the patients, rather to please them than in the hope of relieving 

 them. However, it seemed to have a good effect, but why? I should 

 not dare to make a guess. I do not doubt that these symptoms of the 

 lofty mountains are merely temporary and that custom would end 

 them, as it does seasickness. They become much more intense when 

 one makes an ascent when he is already at a great height. 



July 11, we camped 500 feet below the pass. There the headaches 

 and nausea stopped quickly. (P. 56 et seq.) 



July 20, crossing of the pass of Cayley, a newly discovered 

 pass, easy of access, which is about 5900 meters high; through it 

 one goes from the basin of the Indus to the plateaux of Yarkand; 

 there was no snow. The travellers found several butterflies there. 

 They do not speak of any physiological disturbance. 



