20 Historical 



summer are frequently situated between 4500 and 4900 meters; 

 Norbu, for instance, is at 4860 meters. In summer, the herds feed 

 in pastures as high as 5000 meters, like that of Larsa, at 4980 

 meters. 10 On the high plateaux of Vokhan and Pamir, the Kirghiz 

 bring their yaks and sheep to the elevation of 4700 meters. The 

 Mirza sent by M. Montgomerie to Thibet even mentions a village, 

 Thok-Djalank, at the extraordinary height of 4980 meters. 



The Andes and the Himalayas include the only two regions of 

 the earth where populations numbering millions of souls live 

 regularly above 3000 meters. On the lofty plateaux of Mexico, the 

 regions inhabited by a great number of men are as low as about 

 2000 meters; in Abyssinia, they are lower yet; Gondar is at 2220 

 meters and the village of Endschetkab, which seems to be the 

 highest in Abyssinia, at 2960 meters. 



About the same thing is true of the mountain dwellers in 

 Armenia: Ispahan is situated at 1340 meters, Erzeroum at 1860 

 meters and Kars at 1900 meters. In Europe, as we have seen, the 

 level is still lower. 



Men who live at these heights are certainly in conditions very 

 different from those encountered at sea level. At 5500 meters, a 

 liter of air weighs exactly half as much as at sea level; at 3300 

 meters, a third less; at 2300 meters, a quarter less. Are these 

 special conditions helpful or harmful to the material or intellectual 

 development of man? I shall try to discuss this question in the 

 third part of this book. I must remind my readers, furthermore, 

 that slow, progressive influences, which the sojourn in lofty moun- 

 tains may exert on successive generations, will be given little atten- 

 tion. For these important questions in hygiene and politics, I refer 

 my readers to the noteworthy book of M. Jourdanet. In this work, 

 and especially in the part devoted to the discussion of historical 

 records, I shall deal only with sudden and evident symptoms caused 

 in men and animals by an abrupt and considerable change in alti- 

 tude and consequently in barometric pressure. And so in the fol- 

 lowing pages I shall refer to the accounts of travellers, generally 

 telling their own experiences. 



I have divided this historical part into three distinct chapters. 

 The first contains the reports of which I have just spoken; I have 

 classified them by orographic regions and listed them chronologi- 

 cally. I certainly do not claim that this list is absolutely complete; 

 but I think I have omitted nothing that is really interesting. 



In the second chapter the accounts of aeronauts are reported. 

 Finally, in the third I have arranged the laboratory experiments, 



