Niagara is the outlet of several bodies of water, covering, it is estimated, 150,000 square miles! Dr. Dwight considers the Falls as part of the St. Lawrence, following that river back to the sources near the Mississippi; and, doing away with the intermediate names of St. Marie, Detroit, St. Clair, Iroquois, and Cataraqui, he traces its course through the lakes Superior, Huron, Erie, and Ontario, as the Rhone is followed through the Lake of Geneva, and the Rhine through Lake Constance. In this view the St. Lawrence is doubtless the first river in the world. It meets the tide of the sea four hundred miles from its mouth, which is ninety-five miles broad; and to this height fleets of men of war may ascend and find ample room for an engagement. Merchantmen of all sizes go up to Montreal, which is six hundred miles from the sea; and its navigation for three thousand miles is only interrupted in three places,—Niagara Falls, the rapids of the Iroquois, and the part called the river St. Marie. The St. Marie is navigable for boats, though not for larger vessels; a portage of ten miles (soon to be superseded by a ship canal) conveys merchandise around the Falls of Niagara, and the rapids of the Iroquois present so slight a hinderance, that goods are brought from Montreal to Queenston for nearly the same price as they would pay by unobstructed navigation.