ANNOTATIONS AND ADDITIONS. 93 



bushes which serve the inhabitants for fuel to warm their huts, 

 attain, in the latitude of 30f and 31 of north latitude, a height 

 of 2650 toises (16,945 English feet), or almost 200 toises (1279 

 English feet) higher than the limit of perpetual snow under the 

 equator. From the data hitherto collected it would follow, that we 

 may take the lower limit of perpetual snow on the northern side of 

 the Himalaya, on the average, and in round numbers, at 2600 toises, 

 or about 16,600 English feet; whilst on the southern declivity of 

 the Himalaya the snow-line sinks to 2030 toises, or about 13,000 

 English feet. 



But for this remarkable distribution of temperature in the upper 

 strata of the atmosphere, the mountain plain of Western Thibet 

 would be uninhabitable to the millions who dwell there. (Compare 

 my Examination of the Limit of Perpetual Snow on the two declivi- 

 ties of the Himalaya, in the Asie Centrale, t. ii. pp. 435437; t. 

 iii. pp. 281-326, and in Cosmos, Engl. ed., vol. i., note 403; s. 

 483 of the original.) 



A letter which I have just received from India from Dr. Joseph 

 Hooker, who is engaged in meteorological and geological researches, 

 as well as those connected with the geography of plants, says : " Mr. 

 Hodgson, whom we regard here as the geographer best acquainted 

 with the hypsometric relations of the snow ranges, completely re- 

 cognizes the correctness of your statement in the third part of the 

 Asie Centrale, respecting the reason of the inequality in the height 

 of the limit of perpetual snow on the northern and southern declivi- 

 ties of the Himalaya. In the < trans Sutlej region' in 36 lat. we 

 often saw the snow limit only commence at an altitude of 20,000 

 English feet, while in the passes south of the Brahmaputra, between 

 Assam and Burman, in 27 lat., where the most southern Asiatic 

 snowy mountains are situated, the limit of perpetual snow sinks to 

 15,000 English feet." I believe we ought to distinguish between 

 the extreme and the mean heights, but in both we see manifested 

 in the clearest manner the formerly contested differences between 

 the Thibetian and the Indian declivities. 



