524 PORTILLO PASS. [chap. xt. 



scanty. The root of a small scrubby plant served as fuel, but it 

 made a miserable fire, and the wind was piercingly cold. Being 

 quite tired with my day's work, I made up my bed as quickly as 

 I could, and went to sleep. About midnight I observed the sky 

 became suddenly clouded : I awakened the arriero to know if 

 there was any danger of bad weather ; but he said that without 

 thunder and lightning there was no risk of a heavy snow-storm. 

 The peril is imminent, and the difficulty of subsequent escape 

 great, to any one overtaken by bad weather between the two 

 ranges. A certain cave offers the only place of refuge : Mr. 

 Caldcleugh, who crossed on this same day of the month, was de- 

 tained there for some time by a heavy fall of snow. Casuchas, 

 or houses of refuge, have not been built in this pass as in that of 

 Uspallata, and therefore, during the autumn, the Portillo is little 

 frequented. I may here remark that within the main Cordillera 

 rain never falls, for during the summer the sky is cloudless, and 

 in winter snow-storms alone occur. 



At the place where we slept water necessarily boiled, from the 

 diminished pressure of the atmosphere, at a lower temperature 

 than it does in a less lofty country ; the case being the converse 

 of that of a Papin's digester. Hence the potatoes, after remain- 

 ing for some hours in the boiling water, were nearly as hard as 

 ever. The pot was left on the fire all night, and next morning 

 it was boiled again, but yet the potatoes were not cooked. I 

 found out this, by overhearing my two companions discussing the 

 cause ; they had come to the simple conclusion, " that the cursed 

 pot (which was a new one) did not choose to boil potatoes." 



March 22nd. — After eating our potato-less breakfast, we 

 travelled across the intermediate tract to the foot of the Portillo 

 range. In the middle of summer cattle are brought up here to 

 graze ; but they had now all been removed : even the greater 

 number of the guanacos had decamped, knowing well that if 

 overtaken here by a snow-storm, they would be caught in a trap. 

 We had a fine view of a mass of mountains called Tupungato, 

 tlie whole clothed with unbroken snow, in the midst of which 

 there was a blue patch, no doubt a glacier ; — a circumstance of 

 rare occurrence in these mountains. Now commenced a heavy 

 and long climb, similar to that up the Peuquenes. Bold conical 

 liiiis of red granite rose on each hand ; in the valleys there were 



