134 T. C. ELLIOTT
the mouth of Big Sandy River in Oregon. The source of the Columbia River was discovered in July, 1807, by David Thompson, an English fur trader from east of the Rocky Mountains, to whom belongs the honor of first traversing the entire river, between source and mouth. That event took place in 1811 and has not been often repeated since.
The first serious obstruction to the navigation of the Co- lumbia river is the stretch of rapids 160-165 miles from its mouth, which has been curiously misnamed "The Cascades." These rapids were designated by Lewis and Clark in 1805-6 as "The Great Shutes," but were as early as 1811 known to the fur traders as The Cascades. This hindrance has been re- moved by a system of government locks, which were begun in 1878 and formally opened for use on November 5th, 1896. The next serious obstruction begins at the foot of The Dalles (Big Eddy), practically two hundred miles from the mouth of the river, and extends ten miles to include Celilo Falls, and has now been overcome by the Dalles-Celilo Canal, eight and a half miles in length. The river is now open for navigation as far as Priest Rapids, 420 miles from its mouth; and its principal tributary, the Snake River, to points beyond Lewis- ton, Idaho, more than 500 miles from the ocean. Both the locks at the Cascades, and the Dalles-Celilo Canal are located on the south or Oregon side of the river.
There are numerous rapids and falls in the Columbia river, which were given their original names by the French- Canadian or mixed-blood voyageurs who manned the canoes and bateaux affording the first means of transportation on the river; Les Dalles des Morts, or Death Rapids (in British Columbia), Les Chaudiere or Kettle Falls, Isle de Piere or Rock Island Rapid, Rapide du Pretre or Priest Rapid. Several other parts of the river were designated as Les Petite or Little Dalles, but to this part was originally given the name of Grande Dalles. Here the mighty river turns literally upon edge and through two successive rock-ribbed channels (more clearly described as sunken mill races) together measuring nearly two and a half
