REGION OF LAKES. 381 



Here commences a remarkable region of lakes, com- cilAPTKR 

 prising the group of Balek-koul (lat, 51° 30'), and that -"^VIll. 

 of Koumkoul (lat. 49° 45'), indicating an ancient com- 

 munication of a mass of water with the Lake Ak-sakal, Lakes. 

 which receives the Tourgai and the Kamichloi Irgliiz, 

 as well as with the Lake Aral ; and which would seem 

 from Chinese accounts to have formed part of a great 

 plain extending to the borders of the Frozen Sea. 



The mean latitude of the system of the Thian Chan System of 

 chain is the 42d degree. Its highest summit is perhaps '''^" '^"^ 

 the mass of mountains covered with perpetual snow, and 

 celebrated under the name of Bokhda-oola, from which 

 Pallas gave the designation of Bogdo to the Avhole chain. 

 From Bokhda-oola and Khatoun-bokhda, the Thian Chan, 

 or Celestial Mountains, run eastward towards Barkoul, 

 where they are suddenly lowered so as to fall to the level 

 of the elevated desert, called the great Gobi or Shamo, 

 which extends from Koua-tcheou, a Chinese town, to 

 the sources of the Argoun. This forms, in reality, the Great moun 

 great mountain chain of Central Asia. It extends almost central Asia 

 uninterruptedly from east to west, between the latitudes 

 of 40i^° and 43°, and is crossed by the meridional chain 

 of Bolor, in east longitude 72° and latitude 401°. These 

 two mountain chains cross each other nearly at right 

 angles, and mark the results of two great epochs of up- 

 heaval. They are, accordingl}', characterized by very 

 diverse mineral characteristics, into the consideration 

 of which the scientific traveller has entered with great 

 acuteness and considerable minuteness of detail. If 

 we now return to Bokhda-oola, we find the western 

 prolongation of these mountains stretching to Goudja 

 and Koutche, then between Lake Temourtou and Aksou 

 to the north of Cashgar, and running towards Samarcand. 

 The country comprehended between the Altaic chain 

 and the Thian Chan mountains is shut up to the east, 

 beyond the meridian of Pe-king, by the Khingkhan-oola, 

 a lofty ridge, which runs from south-west to north-east ; 

 but to the west it is entirely open. 



