Lofty Regions of the Globe 5 



this volcano they are slight, attack only part of the travellers, and 

 might be confused with the ordinary effects of fatigue. The same 

 thing is true in crossing the Pyrenees and the Alps. The passes of 

 the Pyrenees, through which regular communications were estab- 

 lished between Gaul and Hispania, are hardly 1,500 meters high. 

 Whatever opinion one has about the site of the passage of Hannibal, 

 either at the Little Saint-Bernard (2,160 meters), or the pass of 

 Mount Viso (2,700 meters), or Mount Cenis (2,080 meters), or in 

 the valley of Beaufort between Albert- Ville and Chamounix, the 

 heights reached were not very great. Augustus had two roads made 

 through the passes of the Great Saint-Bernard (2,490 meters) and 

 the Little Saint-Bernard, 4 and King Cottus, his contemporary, cut 

 the road of Mount Cenis. In the Middle Ages, the Simplon (2,020 

 meters) and the Great Saint-Bernard were much frequented; 

 chroniclers have left us descriptions of these journeys or these 

 expeditions in which the terrible difficulties of the roads, the ex- 

 cessive fatigue, and the cold explain sufficiently the pitiful state 

 of the travelers, many of them, like Elfrid, archbishop of Canter- 

 bury, perished in the snow. 



To attract the attention of the travellers to physiological symp- 

 toms they would have had to make more lofty ascents, and to have 

 suffered discomforts evidently unexplainable by ordinary causes. 

 The lofty summits of the Alps presented the necessary conditions, 

 as we shall see; but since their ascents offered no practical interest, 

 they were undertaken only toward the end of the last century. 

 But twenty years after the discovery of America, the conquest of 

 Mexico and Peru and military expeditions across the Cordilleras 

 brought the Spaniards into conditions where the symptoms of de- 

 compression appeared definitely. So attention was soon attracted 

 to them, and they were noted in ascents where they are neither 

 great nor constant, like those of Etna and the Peak of Teneriffe. 

 However, our Alps for a long time still remained unexplored; 

 though the important cities and the rich valleys of Switzerland 

 attracted many travelers, no one had the idea of climbing these 

 dangerous peaks covered with snow, peopled with strange beings, 5 

 and about which the most gloomy tales were told. It was not until 

 the second half of the eighteenth century that people decided to 

 admire them and that the idea of reaching their summits germi- 

 nated in a few minds. It was the scientific point of view that 

 guided the first ascents. In the account of his ascents de Saussure 

 noted with keen alertness the symptoms brought on by a stay in 

 rarified air. Since then, similar observations are numerous. Still 



