n12 0::            TOPOGBAPIIOAL.
725 miles from its mouth. From that point it could be navigated till further for 150 miles into the heart of the richest mining regions of British Columbia. At the Cascades, where, in the length of four miles, the river falls a distance of 300 feet, the United States Government is constructing a series of locks, which will assist navigation materially as soon as they are finished.
SNAKE RIVER.-The source of the Snake river is in 410 N., and 1110 W. It is one of the largest affluents of the Columbia, and its main tributaries are the Grande Ronde, the Powder, the Burnt, the Malheur, and the Owyhee rivers. From its confluence, at Ainsworth, with the Columbia, it is navigable to Lewiston, in Idaho, a distance of over 150 miles.
WILLAMETTE RIVER.-This important stream    rises in the Cascade Mountains, and with the exception of the Columbia, is the chief river in Oregon. The Willamette is formed by the three streams known as McKenzie's, Middle and Coast forks. It is navigable for the largest ocean steamships and sailing vessels to Portland, 112 miles from the sea. At Oregon City it falls perpendicularly over a ledge of rocks about 40 feet high. Formerly these falls proved an absolute obstruction to direct navigation, and a passage around them was secured by a portage on the right bank of the river. Subsequently, at a cost of several hundred thousand dollars, locks were constructed, allowing the direct passage of steamboats. Now these vessels navigate the river during high water as far as Eugene City, 138 miles from Portland, and as far as Salem, 51 miles, during the whole year. Small steamers of very light draught have been recently introduced in order that the river may be navigated uninterruptedly at every season. The main tributaries of the Willamette are the Tualatin, the Clackamas, the Yamhill, the Mollala, the Santiam, the Luckiamute, the Mary and the Long Tom rivers.
OTHER RIVERS. -The largest rivers which empty into the Pacific Ocean along the coast of Oregon are the Rogue, the Coquille, the Umpqua, the Siuslaw, the Alsea, the Siletz and the Nehalem. North of the entrance to the Columbia River, on the coast of Washington Territory, the rivers Talux, Nasal and Willopah flow into Shoalwater Bay, and the Chehalis river and other streams empty into Gray's Harbor. Thirty-eight miles south of Cape Flattery the Quillyhuyte river flows into the Pacific Ocean. Most of these rivers are navigable for long distances, and beside them are very many more which afford passage for vessels of light draft.
PUGET SOUND REGION.-This great body of tide-water, often called the Mediterranean of America, covers an area within Washington Territory of over 2,000 square miles, and has a shore line of