Summary and Discussion 327 



4500 meters, whereas in our Alps it is not rare a thousand meters 

 lower, temperature certainly has much to do with this considerable 

 irregularity; as I remarked a moment ago, the zone of eternal snow 

 is almost the same as that in which the symptoms appear. If the 

 city of Cerro de Pasco is so much dreaded by all travellers, that is 

 because its icy climate increases the severity of the symptoms 

 caused by the altitude. Evidently it is to their position on the 

 equator that the immense mountains which surround Quito owe i> 

 part the relative immunity enjoyed by the persons who ascend 

 them. At Quito, says Jameson,- the average temperature is about 

 14°; the thermometer fluctuates between 18° and 8°. 



But this element is not the only one. There is a great differ- 

 ence, judging by what we said before, between a mountain situated 

 on the shore of the ocean, like the Peak of Teneriffe (3715 meters) , 

 for example, and another of the same height in the main range of 

 our Alps, like Galenstock (3800 meters) . To make the ascent of 

 the former, in fact, the traveller starts from sea level, and in one 

 stretch covers a considerable vertical height; in the case of the 

 second, the distance to be traversed is lessened by at least 1000 

 meters. In the latter case, the transition is infinitely slower. More- 

 over, one cannot even approach the foot of the Alps without 

 having had a sort of acclimatization with muscular training, in- 

 stead of merely disembarking at the foot of the Peak or Etna. 

 And so on these mountains of moderate height, in spite of the 

 high temperature of their region, symptoms are still more fre- 

 quent than on mountains of similar height in the Alps. 



For the same reason, in addition to their situation in the torrid 

 zone, Chimborazo, Antisana, Cotopaxi, etc. cause only moderate 

 symptoms; the city of Quito, which is at their feet, and from which 

 one starts after a longer or shorter sojourn, is situated at an alti- 

 tude of 2910 meters, so that there remains a vertical ascent of only 

 1950 meters to the summit of Pichincha; and so here we recall the 

 irreverent comparison of Canon Bourrit (page 13) . 



The reader may convince himself, by reviewing the journeys 

 across the Andes (pages 22-59) , that the symptoms are much more 

 general and much more severe among travellers going from the 

 Pacific to the Atlantic, than among those going in the opposite 

 direction. In my opinion, the explanation of this apparent pecu- 

 liarity lies partly in the fact that from the coast of Chile the 

 ascent is extremely steep, whereas it is slow and progressive for 

 the traveller going from the east to the west. 



The considerable height to which one must ascend in the Hima- 

 layas before being attacked by mountain sickness may be due to 



