694 Limits of Perpetual Snow in the Himalayas. [July, 



Note on the Limits of Perpetual Snow in the Himalayas. By Capt. 

 J. D. Cunningham, Engineers. 



I have just read Lieut. R. Strachey's interesting paper on the 

 limits of perpetual snow in the Himalayas,* in which he satisfac- 

 torily establishes that the elevations hitherto assigned to the pheno- 

 menon have been under-estimated, and that in truth snow is only 

 to be permanently found at about 15,000 feet, on the southern, and at 

 about 18,000 feet on the northern boundaries respectively, instead of at 

 about 13,000 and 16,500 feet, as hitherto supposed. Lieut. Strachey 

 very well shows that Humboldt has attached undue weight to the casual 

 or partial observations of travellers and others infixing upon the smaller 

 numbers, but he appears to me to be himself in error when he assigns 

 the greater elevation on the northern side almost solely to the smaller 

 quantity of snow which there falls, although he is pleased to attach 

 value to my testimony that such quantity is indeed relatively small, and 

 thus to make me in a way a supporter of his theory. 



Humboldt's view of causes correct. — Humboldt, in his " Cosmos" 

 (Sabine's Trans. I. 328,) enumerates the contingencies on which the 

 limits of the snow line are dependent, and to me he seems truly to 

 refer the superior height on the northern side of the Himalayan chain 

 to the general elevation of Tibet, i. e. to the heat due to radiation and 

 reverberation even at that great height above the sea. This view is 

 strikingly borne out by what that able officer, the late Dr. Lord, 

 observed with reference to the Hindu Koosh.f He found the snow 

 lying very much lower on the northern than on the southern face, and 

 he gives as a reason for the large difference the existence of the high 

 lands of Cabul on the south side, or the fact that these high lands 

 contain latent heat which melts the snow, while on the northern face 

 the slopes merge into the swampy flats of Toorkistan, scarce 500 feet 

 above the sea, and are thus met by a cold atmosphere, down to a low 

 level, in aid of the coldness due to a northern aspect. 



* Journ. As. Soc. of Bengal, No. 102, April, 1849. 



f Reports on Sindh, Afghanistan, &c., by Sir A. Burnes, Lieut. Leech, Dr. Lord 

 and Lieut. Wood. (Geographical Memoirs, pi 48, &c.) 



