72 VIEWS OF NATURE. 



of actual measurements, since the indication which led the 

 natives of Quito, long before the arrival of Bouguer and La 

 Condamine, to regard the summit of the Chimborazo as the 

 culminating point or the highest point within the region of 

 perpetual snow is rendered very deceptive in the temperate 

 zone of Thibet, where the radiation of the table-land is so 

 effective, and where the lower limit of perpetual snow does 

 not constitute a regular line of equal level as in the tropics. 

 The greatest elevation above the level of the sea that has been 

 reached by man on the sides of the Himalaya is 19,488 

 feet. This elevation was gained by Captain Gerard, with 

 seven barometers, as we have already observed, on the moun- 

 tain of Tarhigang, somewhat to the north-west of Schipke.* 

 This happens to be almost the same height as that to which 

 I myself ascended up on the Chimborazo (on the 23rd of 

 June, 1802), and which was reached thirty years later (16th 

 of December, 1831) by my friend Boussingault. The un- 

 attained summit of the Tarhigang is, moreover, 1255 feet 

 higher than the Chimborazo. 



The passes across the Himalaya from Hindostan to Chinese 

 Tartary, or rather to Western Thibet, especially between 

 the rivers Buspa and Schipke, or Langzing Khampa, are 

 from 15,347 to 18,544 feet in height. In the chain of the 

 Andes I found that the pass of Assuay, between Quito 

 and Cuenca, at the Ladera de Cadlud, was* also fully 15,566 

 feet above the level of the sea. A great part of the Alpine 

 plains of the interior of Asia would lie buried throughout 

 the whole year in snow and ice, if the limits of perpetual 

 snow were not singularly elevated, probably to about 16,626 

 feet, by the force of the heat radiated from the Thibetian 

 plain, the constant serenity of the sky, the rarity of the for- 

 mation of snow in the dry atmosphere, and by the power- 

 ful solar heat peculiar to the eastern continental climate, 

 which characterizes the northern declivity of the Himalaya. 

 Fields of barley (of Hordeum hexast'.chori) have been seen in 

 Kunawur at an elevation of 14,700 feet and another varitey 

 of barley, called Ooa, and allied to Hordeum cceleste, even 



* Colebrooke, in the Transactions of the Geological Society, vol. vi. 

 p. 411. 



