Appendix E. DISTRIBUTION OF PERPETUAL SNOW. -395 



conveys a false impression. It is better to say that the snow lies 

 deeper and lower on the southern faces of the individual moun- 

 tains and spurs that form the snowy Himalaya. The axis itself of the 

 chain is generally far north of the position of the spurs that catch all 

 the snow, and has comparatively very little snow on it, most of what 

 there is lying upon north exposures. 



A reference to the woodcut will show that the same circumstances 

 which affect the distribution of moisture and vegetation, determine 

 the position, amount, and duration of the snow. The principal fall 

 will occur, as before shown, where the meridional range first attains 

 a sufficiently great elevation, and the air becomes consequently cooled 

 below 32° ; this is at a little above 14,000 feet, sporadic falls occurring 

 even in summer at that elevation : these, however, melt immediately, 

 and the copious winter falls also are dissipated before June. As the 

 depth of rain-fall diminishes in advancing north to the higher parts 

 of the meridional ranges, so does that of the snow-fall. The perma- 

 nence of the snow, again, depends on — 1. The depth of the accumula- 

 tion ; 2. The mean temperature of the spot ; 3. The melting power of 

 the sun's rays ; 4. The prevalence and strength of evaporating winds. 

 Now at 14,000 feet, though the accumulation is immense, the amount 

 melted by the sun's rays is trifling, and there are no evaporating 

 winds ; but the mean temperature is so high, and the corroding 

 powers of the rain (which falls abundantly throughout summer) and 

 of the warm and humid ascending currents are so great, that the 

 snow is not perennial. At 15,500 feet, again, it becomes perennial, 

 and its permanence at this low elevation (at P) is much favoured by 

 the accumulation and detention of fogs over the rank vegetation 

 which prevails from S nearly to P ; and by the lofty mountains 

 beyond it, which shield it from the returning dry currents from the 

 north. In proceeding north all the circumstances that tend to the 

 dispersion of the snow increase, whilst the fall diminishes. At P the 

 deposition is enormous and the snow-line low — 16,000 feet ; whilst 

 at T little falls, and the limit of perpetual snow is 19,000 and 20,000 

 feet. Hence the anomaly, that the snow-line ascends in advancing 

 north to the coldest Himalayan regions. The position of the greatest 

 peaks and of the greatest mass of perpetual snow being generally 

 assumed as indicating a ridge and watershed, travellers, nrguing from 



