ANNOTATIONS AND ADDITIONS. 99 



erful solar heat peculiar to the eastern continental climate, the 

 limit of perpetual snow is wonderfully raised on the northern 

 slope of the Himalaya, perhaps to 2600 toises, or 16625 

 English feet above the level of the sea. Fields of barley 

 (Hordeum hexastichon) are seen in Kunawur up to 2300 

 toises, or 14707 English feet ; and another variety of barley 

 called Ooa, and allied to Hordeum cceleste, even much higher. 

 Wheat succeeds extremely well in the Thibetian highlands 

 up to 1880 toises, or 12022 English feet. On the northern 

 declivity of the Himalaya, Captain Gerard found the upper 

 limit of the higher birch woods ascend to 2200 toises, 14068 

 English feet ; and small 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 650 toises 

 (16945 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 16600 English feet; 

 whilst on the southern declivity of the Himalaya the snow- 

 line sinks to 2030 toises, or about 13000 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 declivities of the Himalaya, in 

 the Asie Centrale, T. ii. p. 435-437 ; T. iii. p. 281-326, 



