Irtish

Irtish, a river of Siberia, the chief affluent of the Obi (q.v.), rises at the east end of the Altai Mountains, passes through Lake Saisan, breaks through the Altai in the west at the bottom of a savage gorge, and flows north-westwards across the steppes of Western Siberia to join the Obi, from the left, at Samarow. At that point it has a width of 2000 yards; its total length is 1620 miles; the area of its basin, 647,000 sq. m. The important towns of Semipalatinsk, Omsk, and Tobolsk stand on its banks. From April to November it is navigable from its mouth as far as Lake Saisan; during the rest of the year traffic is carried on by means of sledges. Its current is gradually shifting eastwards. Its best-known tributaries are the Buchtarma and Om from the right, and the Tobol and Ishim from the left.