ANNOTATIONS AND ADDITIONS. 77 



Bolor, or Bulyt-Tagh, (" cloud mountains" in the Uigurian 

 dialect) which follow a north and south direction, and 

 from the upper Oxus, (whose sources were found by the 

 Buddhistic pilgrims Hiuen-thsang and Song-yun in 518 

 and 629, by Marco Polo in 1277, and by Lieutenant 

 "Wood in 1838, in the Pamer Lake, Sir-i-kol, Lake 

 Victoria), towards the Caspian j and from Tenghir or the 

 Balkhash Lake through the Kirghis Steppe, towards the 

 sea of Aral and the southern extremity of the Ural moun- 

 tains. As compared with high plains of 6,000 to 10,000 

 feet above the level of the sea, it may well be permitted to 

 use the expression of " lowlands" for flats of little more 

 than 200 to 1200 feet of elevation. The lowest of the 

 last two numbers corresponds nearly to the altitude of 

 the town of Mannheim, and the highest to that of Geneva 

 and Tubingen. If the word plateau, so often misemployed 

 in modern works on geography, is to have its use extended 

 to elevations which hardly present any sensible difference in 

 climate and vegetation, the indefiniteness of the expres- 

 sions "highlands and lowlands," which are only relative 

 terms, will deprive physical geography of the means of 

 x expressing the idea of the connection between elevation 

 and climate, between the profile or relief of the ground 

 and the decrease of temperature. When T found myself 

 in Chinese Dzungarei, between the boundary of Siberia 

 and Lake Dsaisang, at an equal distance from the Icy Sea 

 and from the mouth of the Ganges, I might well consider 

 myself in Central Asia. The barometer, however, soon 

 taught me that the plains through which the Upper 

 Irtysh flows, between Ustkamenogorsk and the Chinese 



