Niagara (Niag'ara - originally Neeagah'ra; 'Thunder of Waters'), a river of North America, which forms part of the boundary between New York state and the province of Ontario. It flows from Lake Erie to Lake Ontario, a course of 36 miles, during which it makes a total descent of 326 feet - about 50 feet in the rapids immediately above the great falls, and nearly 110 feet in the seven miles of rapids below. It encloses several islands, the largest Grand Island, which is nearly 10 miles long. Four miles below this island are. the most famous falls in the world. The centre of the river here is occupied by Goat Island, dividing the cataract into two - the Horseshoe (Canadian) Fall, with a descent of 158 feet, and the American fall, 162 to 169 feet; the width of the former is about 2640 feet, of the latter 1000 feet. The volume of water which sweeps over this immense chasm (nearly nine-tenths passing over the Canadian fall) is about 15,000,000 cubic feet a minute. The depth of water on the crest of the falls is less than 4 feet, except in a few places, notably at the apex of the Horseshoe Fall, where it is about 20 feet. The limestone edge of both falls is rapidly wearing away in the centre. For seven miles below the falls (to the point, that is, where it has been supposed that the falls originally stood) the river is shut in between perpendicular walls of rock, from 200 to 350 feet high. For some distance below the falls there is still water, the body of water which pours over the precipice sinking, and only coming to the surface again two miles below, where the whirlpool rapids begin; a little lower is the whirlpool, where a sharp turn sends the waters hurling against the Canadian side, and then sweeping round in a great eddy before they find a vent at a right angle with their former course. Just below the cataract the river is crossed by a suspension bridge for carriages and foot-passengers, and a mile and a half farther down there are two railway bridges - one a cantilever bridge - about 100 yards apart. On both shores the lands bordering on the river, for some distance above and below the falls, are under the immediate control of the respective governments. The 'New York State Park at Niagara Falls' (1885) embraces 115 acres, and the ' Queen Victoria Niagara Falls Park' (1888) about 154 acres. Only in 1890 was the tunnel begun for the utilisation of the water-power of the falls to generate electricity for transmission to more or less distant centres; by 1900 one company alone had usefully applied 40,000 horse-power, and by 1904 the plant on the Canadian side alone represented 675,000 horse-power (partly transmitted to Toronto). - Niagara Falls, a city of New York, is connected by the suspension bridge with the Canadian side. Pop. 20,000. - Niagara, a summer-resort of Ontario, is situated on Lake Ontario, at the mouth of the Niagara, 15 miles from the falls. Pop. 4250.