60 • M. Boussingaulfs [July 



It was at 7 o'clock on the morning of the 16th, that we 

 hegan to ascend by the route of Alenal. The sky was 

 remarkably clear. To the east we observed the famous 

 volcano of Langay, situated in the province of Macas, and 

 which, only a century ago, Condamine had seen in a state 

 of permanent eruption. In proportion as we advanced, the 

 ground became elevated in a sensible manner. In general 

 the plateaus of trachyte, which supported the isolated 

 peaks, of which the Andes consist, rise gradually towards 

 the base of these peaks. The numerous deep crevices which 

 furrow these plateaus appear to diverge from a common 

 centre and become narrower in proportion to their distance 

 from the centre. They exactly resemble the cracks which 

 are observed on glass which has been starred. At 9 o'clock 

 we halted to breakfast under the shade of an enormous 

 block of trachyte, to which we gave the name of Pedron del 

 Almuenzo. 



Here I made a barometrical observation, because I was 

 in hopes of being able to take another at 4 P. M., in order 

 to ascertain at this height the diurnal variation. Pedron 

 is elevated 4335 metres (14,218 feet). We passed on our 

 mules the limit of the snow. When we began to ascend on 

 foot the height was 4945 metres (16,219 feet). The ground 

 was quite unfitted for our mules to travel on. These 

 animals endeavoured to make us comprehend by their 

 instinct the lassitude which they endured; their ears 

 generally so erect and attentive were completely flattened, 

 and during the frequent halts which they made, in order 

 to breathe, they gazed anxiously on the plain beneath. 

 Few persons have, it is probable, rode to such an elevation ; 

 for in order to keep one's seat, on animals travelling in 

 such soft ground, it would be necessary to have been 

 accustomed to ride for several years among the Andes. 

 After examining the place where we had stopped, we 

 endeavoured to gain a ridge which mounted to the summit 

 of Chimborazo. It was necessary in the first instance to 

 overcome a great declivity which lay before us ; it was 

 formed principally of blocks of rock of all sizes, disposed in 

 a shelving manner ; these and their fragments of trachyte 

 were covered by larger or smaller pieces of ice, and in 

 several places, it was obvious that this debris rested on 



