ALTIN, a lake of Siberia, in the government of Koli-van, from whence issues the river Ob or Obi, in long. 85. 55. E. lat. 52. 0. N. This lake is called by the Russians Teloskoi Osoro, from the Telessi, a Tartarian nation, who inhabit the borders of it, and who give it the name of Altin-Kul. By the Calmucks it is called Altinnor. It is 84 miles long and 56 broad, with a rocky bottom. The north part of it is sometimes frozen so hard as to be passable on foot, but the southern part is never covered with ice. The water in the Altin lake, as well as in the rivers which run through the adjacent places, only rises in the middle of summer, when the snows on the mountains are melted by the heat of the sun.