ALTIN, a lake in Siberia, from whence issues the river Ob, or Oby, in N. Lat. 52. 0. E. Long. 85. 55. This lake is called by the Russians Teleskoi Ozero, from the Telesti, a Tartarian nation, who inhabit the borders of it, and who give it the name of Altin-Kul. By the Caimucks it is called Altinnor. It is near 90 miles long and 50 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.