KOSELSK, a city of the province of Kaluga, in Russia, the capital of a circle of the same name. It stands at the junction of the river Schisbra with the Dragunka, and is the best built city of the province. It contains broad streets, a spacious market-place, seven churches, four of them of stone, and 559 houses, with 3800 inhabitants, who have considerable trade by the two rivers. Long. 35. 25. E. Lat. 54. 12. N.