( 243.) 
On the Limits of Perpetual Snow in the Himalayas. 
By Captain J. D. CunnineuaM, Engineers. 
I have just read Lieutenant R. Strachey’s interesting paper 
On the Limits of Perpetual Snow in the Himalayas, in which 
he satisfactorily establishes that the elevations hitherto as- 
signed to the phenomenon 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. Lieutenant Strachey 
very well shews that Humboldt has attached undue weight 
to the casual or partial observations of travellers and others 
in fixing 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 contin- 
gencies on which the limits of the snow-line are depen- 
dent ; and to me he seems truly to refer the superior height on 
_ the northern side of the Himalayan chain to the general ele- 
vation of Tibet, 7. e., to the heat due to radiation and rever- 
beration 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.t 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 
t 
_ * Journ. As. Soc. of Bengal, No, 102, April 1849, and Edinburgh New Phil. 
Journal, vol. xlvii., p- 324. 
+ Reports on Sindh, Afghanistan, &., by Sir A. Burnes, Lieutenant Leech, 
Dr Lord, and Lieutenant Wood (Geographical Memoirs, p. 48, &c.) 
