Theories and Experiments 209 



travellers had been deceived in this, because they did not distinguish 

 sufficiently between the different effects. (P. 262.) 



However, Bouguer gives some importance to the decrease in the 

 weight of the air: 



The slight hemorrhages no doubt resulted from the fact that the 

 atmosphere, having less weight, was not of enough assistance by its 

 compression to help the vessels restrain the blood, which, for its part, 

 was still capable of the same action. (P. 261.) 



Ulloa, 18 who in other regions of the Cordillera had seen "riders 

 as sick as those on foot", could not assume, as Bouguer had done, 

 that fatigue was the principal cause of the symptoms. So he does 

 not even mention this hypothesis. But he triumphantly discusses 

 that of the cold. 



The idea of the rarity of the air occurred to him, but one cir- 

 cumstance puzzled him, which puzzled many others, namely, that 

 these symptoms do not appear in the lofty regions near Quito: 



Certainly one cannot attribute this distress to the cold, for if that 

 was the only cause, this illness would be common in all cold countries. 

 It must therefore come from the properties of the air, either its light- 

 ness or some other quality which we do not know. This illness does 

 not appear in the lofty regions of Quito, the altitude of which is as 

 great as that of Peru, for it is different from the sickness which we 

 call paramarse: at least no one has experienced it when the matter 

 was being considered, so that no one has spoken of it, whereas it is 

 very common in the lands lying before these regions. We should note 

 also that those who are likely to vomit at sea are also so inclined on 

 the Punas, whereas those on whom the sea makes no impression do not 

 experience this distress on these peaks either. Something of the sort is 

 felt on the lofty mountains of Europe and other mountain chains; it is 

 peculiar to delicate persons, but these symptoms are not so noticeable 

 or so serious or even so general as in the regions of America. That 

 which is felt in Europe comes only from the rarity of the air and 

 from the cold on these heights, two circumstances which might well 

 produce some ill effect. (P. 117.) 



Then, in regard to the symptoms noted in beasts of burden, 

 Ulloa reports, but only to oppose it, the opinion common in his 

 time and even today almost universally accepted in these regions 

 of South America, that these symptoms are the result of poisoning 

 by metallic emanations from the ground. And yet he cannot keep 

 from believing in some foreign substance permeating the air: 



The inhabitants of these regions say that it is because the animals 

 are then passing over mines, for they claim that the mountains are full 

 of minerals, from which are emitted through the pores of the earth 



