338 COSMOS. 



rises, according to Pentland, in the southern tropical zone 

 (14 30' to 1 8 south latitude), being more than 2665 feet higher 

 in the maritime and western branch of the Cordilleras of 

 Chili, than under the equator near Quito on Chimborazo, 

 Cotopaxi, and Antisana. Dr. Gillies even asserts that much 

 further to the south, on the declivity of the volcano of Peu- 

 quenes (latitude 33), he found the snow-line at an elevation of 

 between 14,520 and 15,030 feet. The evaporation of the snow 

 in the extremely dry air of the summer, and under a cloudless 

 sky, is so powerful, that the volcano of Aconcagua, north-east 

 of Valparaiso (latitude 32 30'), which was found in the expe- 

 dition of the Beagle to be more than 1400 feet higher than 

 Chimborazo, was on one occasion seen free from snow.* In 

 an almost equal northern latitude (from 30 45' to 31) the 

 snow-line on the southern declivity of the Himalaya, lies 

 at an elevation of 12,982 feet, which is about the same as the 

 height which we might have assigned to it from a comparison 

 with other mountain chains ; on the northern declivity, how- 

 ever, under the influence of the high lands of Thibet (whose 

 mean elevation appears to be about 11,510 feet), the snow line 

 is situated at a height of 1 6,630 feet. This phenomenon, which 

 has long been contested both in Europe and in India, and 

 whose causes I have attempted to develope in various works, 

 published since 1820,f possesses other grounds of interest 



* Darwin, Journal of the Voyages of the Adventure and Beagle, 

 p. 297. As the volcano of Aconcagua was not at that time in a state of 

 eruption, we must not ascribe the remarkable phenomenon of the 

 absence of snow to the internal heat of the mountain (to the escape of 

 heated air through fissures), as is sometimes the case with Cotopaxi. 

 Gillies, in the Journal of Natural Science, 1830, p. 316. 



t See my Second Memoirs sur les Montagues de I'Inde, in the 

 Annales de Chimie et de Physique, t. xiv. pp. 5-55; and Asie centrale t 

 t. iii. p. 281-327. Whilst the most learned and experienced travellers 

 in India, Colebrooke, Webb, and Hodgson, Victor Jacquemont, Forbes 

 Eoyle, Carl von Hugel, and Vigne, who have all personally examined 

 the Himalaya range, are agreed regarding the greater elevation of the 

 snow-line on the Thibetian side, the accuracy of this statement is called 

 in question by John Gerard, by the geognosist MacClelland, the editor 

 of the Calcutta Journal, and by Captain Thomas Hutton, assistant 

 surveyor of the Agra Division. The appearance of my work on Central 

 Asia gave rise to a re-discussion of this question. A recent number 

 (vol. iv. January, 1844) of MacClelland and Griffith's Calcutta Jour- 

 nal of Natural History contains, however, a very remarkable and 



