56 Historical 



work. It is finished now, and already the locomotive conveys the 

 travellers up to regions which formerly they could not reach with- 

 out the most strenuous efforts. Strangely enough, nevertheless a 

 certain number of them became ill. In a letter addressed this very 

 year to one of my friends, there is this very characteristic passage: 



A special train came for us at Callao, took us up Reinar to Lima, 

 then from there into the Andes, climbing by successive planes to an 

 altitude of 3450 meters. . . . We thus journeyed 130 kilometers. . . . The 

 temperature had fallen, the rarefaction of the air was such that many 

 persons could not accompany us to the end. They felt extreme oppres- 

 sion and their eyes were bloodshot. 



It would be very desirable to have careful observations made 

 on this railroad and on the Titicaca railroad too; it would be very 

 easy for the professors of the Faculty of Medicine of Lima to do so. 



I shall finish these quotations from the principal general de- 

 scriptions of mountain sickness in the Cordillera of the Andes by 

 copying a very interesting letter written by M. Pissis to Dr. 

 Coignard, who asked him at my request for information which his 

 great experience in the mountains made very valuable to me. The 

 learned geographer in this letter describes very vividly the symp- 

 toms which he felt, but he does not venture upon any explanation: 



Paris, March 17, 1874. 

 Dear Doctor: 



Here are the observations which you requested of me upon the 

 physiological effects of the rarefaction of the air on lofty mountains. 

 The general effects are headaches, nausea, great difficulty in breathing 

 and a contraction in the region of the false ribs, as if one were tightly 

 squeezed by a belt. These symptoms vary greatly, however, according 

 to the age and the constitution of the patients; when I crossed the pass 

 of Tacora (bar. 463 mm.) a negress eighteen to twenty years old, very 

 sturdy, was extremely ill, she had a profuse nasal hemorrhage, whereas 

 her mistress, a woman of about fifty years, of weak constitution, was 

 hardly affected; the same difference is observed in animals; the strong- 

 est horses are the most likely to die. Nasal hemorrhages are frequent 

 in them also. After one has lived a certain time in lofty regions, these 

 effects are no longer felt; the residents of Oruro in Bolivia, at 3,796 

 meters (average barometric pressure 492 mm.) live as if they were on 

 the seashore; the Indians run leagues without getting tired, and after a 

 year's residence, I easily climbed fairly high mountains, which would 

 have been impossible at my arrival. 



The highest point where I saw permanent dwellings are the mines 

 of Villacote in the province of Chayauta; their altitude is 5,042 meters 

 and the atmospheric pressure 421 mm. The Indians work there as 

 they do elsewhere, but they get tired more easily when it snows, for it 

 never rains in these regions; the workmen, even those in the depths of 

 the mines, are ill, and yet the decrease in pressure when it storms is 



