large river of North America, which rises, according to Mackenzie, in the Rocky Mountains, about long. 121° W. and lat. 54° 23' N., and, after a course of about 1500 miles, flows into the Pacific Ocean between Point Adams and Cape Disappointment, in long. 123° 54' W. and lat. 46° 19' N. The three great tributaries of this river are the Multnomah, 139 miles from its mouth, Lewis, 413, and Clark's, 600 miles. The tide flows up to within seven miles of the great rapids, a distance of 183 miles. Vessels of 300 tons burden can ascend to the Multnomah, and large sloops may ascend as far up as the tide. The entrance of the Columbia lies between breakers which extend from Cape Disappointment to a point on the southern shore, over a sort of bar or extensive flat. Ingress and egress is difficult at all seasons, and from October to April extremely dangerous. It is the opinion of experienced navigators that it should not at any time be entered by loaded vessels of 400 tons burden. The westerly wind prevails on this coast, and the sea breaks upon the bar with great violence.