course, falls into the Susquehannah, after running two hundred miles. The whole course of the Susquehannah, from Chesapeak bay to the head of the north-east branch, is four hundred and fifty miles; and, including all its branches, it waters a tract of forty thousand square miles. Where it falls into the sea it is fully a mile broad; at Harrisburg it is nearly of the same breadth, and from three to five feet deep. There are seven falls in this river, which, with the numerous islands and rocks, render it navigable only for a few miles by large vessels. The _River Potomac_ rises on the north-west side of the Alleghany Mountains, and after running a north-east course of sixty miles to Cumberland, is joined eighteen miles below, by a branch coming from the south-west. Thence fifty-four miles farther, it receives the waters of _Licking Creek_, and passes the north mountain into a fine limestone valley, which it waters in a very winding course of forty-five miles in a south-east direction. Here it receives a considerable number of tributary streams, particularly the _Conecocheague_ at Williamsport, and the _Shenandoah_ at the extremity of the valley, and just above the Blue Ridge, through which the combined stream has effected a singularly magnificent passage. About thirty miles farther, it descends one hundred and forty feet in the course of eight or ten miles, to the level of tide-water, which it meets at Georgetown. It is here a quarter of a mile wide; but expands to a mile opposite Washington, and enters the Chesapeak bay by a passage seven and a half miles broad. This is one of the most important of the Atlantic rivers. It is navigable for vessels of any burden to Alexandria, one hundred miles distant; and from thence, for ships of considerable burden, to Georgetown. A lock navigation has been constructed round the first falls, of which there are four in the whole. The largest of these falls is at Matilda, six miles above Georgetown, where the stream, nine hundred feet broad, after flowing through a valley skirted with hills wild as those of the Rhone in Vivari, (says Volney,) falls at once, like the Niagara, from the height of seventy-seven feet, into a deep chasm of solid micaceous granite. From this it escapes, several miles farther down, by a widening of the valley in the lower country. The whole course of the Potomac is three hundred and forty miles. Illustration: Passage of the Potomac through the Blue Ridge.