298 THE SNOW LINE or TITE ANDES. 



doza and Santiago de Chile. The road leading from one 

 of those towns to the other, rises gradually from 700 to 

 1 987 toises ; and after passing the Col des Andes (La 

 Cumbre, between the houses of refuge called Las Calaveras 

 and Las Cuevas), it descends continually as far as the 

 temperate valley of Santiago de Chile, of which the bottom 

 is only 409 toises above the level of the sea. The same 

 survey has made known the minimum of height at Chile of 

 the lower limit of snow, in 33 south latitude. The 

 limit does not lower in summer to 2000 toises.* I think we 

 may conclude according to the analogy of the Snowy Moun- 

 tains of Mexico and southern Europe, and considering the 

 difference of the summer temperature of the two hemi- 

 spheres, that the real Nevadas at Chile, in the parallel of 

 Valdivia (lat. 40), cannot be below 1300 toises; in Valpa- 

 raiso (lat. 33) not lower than 2000 toises, and in that of 

 Copiapo (lat. 27) not below 2200 toises of height. These 

 are the limit-numbers, the minimum of elevation, which the 

 ridge of the Andes of Chile must attain in different degrees 

 of latitude, to enable their summits to rise above the line 

 of perpetual snow. The numerical results which I have 

 just marked, and which are founded on the laws of distri- 

 bution of heat, have still the same importance which they 

 possessed at the time of my travels in America ; for there 

 does not exist in the immense extent of the Andes, from 

 8 south latitude to the Straits of Magellan, one Nevada of 

 which the height above the sea-level has been determined, 

 either by a simple geometric measure, or by the combined 

 means of barometric and geodesic measurements. 



Between 33 and 18 south latitude, between the paral- 

 lels of Valparaiso and Arica, the Andes present towards the 

 east three remarkable spurs, the Sierra de Cordova, the 

 Sierra de Salta, and the Nevados de Cochabamba. Travellers 

 partly cross, and partly go along the side of the Sierra de 

 Cordova (between 33 and 31 of latitude), in their way from 

 Buenos Ayres to Mendoza; it may be said to be the most 

 southern promontory which advances, in the Pampas, to- 

 wards the meridian of 65 ; it gives birth to the great river 

 known by the name of Desaguadero de Mendoza, and extends 



* On the southern declivity of the Himalayas snow begins (3 nearer the 

 equator) at 1V70 uUes. 



