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Thence to the falls, 13 miles above Alexandria, 10 feet.

The tide water flows to the distance of three miles beyond Washington city, where the common tide rises to the height of four feet.

The Potomac, in its course, receives several streams. Of these the most considerable is the Shenandoah, which traverses the Limestone Valley, two hundred and fifty miles in length, and joins the Potomac just before their united streams burst through the chain of mountains called the Blue Ridge.

By a survey of the Potomac, made in 1789, it was ascertained, that at the distance of fifteen miles above the city of Washington, this river is a hundred and forty-three feet higher than at tide-water: that from the mouth of Savage River to Cumberland, a distance of thirty-one miles, the descent is four hundred and forty-five feet, or 14 per mile; and from Fort Cumberland to tide-water, a dis

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By Messrs. Gilpin and Smith.

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tance of a hundred and eighty-seven miles, the descent is seven hundred and fifteen feet, or 3.29 per mile.

By a survey, made in 18061, at the expence of the Potomac Company, it was ascertained, that the Shenandoah river, from its mouth to Port Republic, has nearly the same breadth during all this distance of two hundred miles, of which the descent is but four hundred and thirty-five feet.

Both these rivers have been lately rendered navigable by means of locks and canals, constructed at very considerable expence. At the great falls of the Potomac, boats pass through a canal one mile in length, six feet deep, and twenty-five feet wide, descending seventy-six feet by means of five locks, each one hundred feet long, and twelve feet wide: on re-entering the Potomac, its course leads to another canal (at the little falls) of the same capacity, and two miles and a half in length, furnished with three other locks, of which the descent is thirty-seven feet to tide-water. The two last locks, at the great falls, cut out of the solid rock, are each a

By Leonard Hasbrough.

hundred feet in length, twelve in breadth, and eighteen in depth, containing about 25,200 cubic feet of water. This work was executed in the space of two years, by a hundred workmen. The other three locks are lined with stone, which is found near the river at the distance of ten miles above the falls. The sluice-gates are of cast-iron, and turn on a pivot fixed in the centre, so that the edge of the gate, when open, is directed towards the stream.

The locks of the little falls, three in number, are constructed of wood, and are each a hundred feet in length, and eighteen in breadth. Mr. Gallatin, late Secretary of the Treasury, from whose report we derive our information on this subject, observes, that this breadth, which consumes much water, is unnecessary. It has been proposed to substitute stone in the place of wood.

Three canals, without locks, have also been completed. The first, below Harper's Ferry, at Shenandoah Falls, where the Potomac breaks through the Blue Ridge, is a mile in length. The second, along the Seneca Falls, is three-quarters of a mile. The third, at

House's Falls, five miles above those of Shenandoah, is fifty yards in length.

The Shenandoah river, from Port Republic till within eight miles of the Potomac, a distance of nearly two hundred miles, has a gradual descent of about two feet in the mile, except the last eight, of which the descent is ten feet. By means of locks and canals, this river is now navigable from its mouth to the Port called Republic; and it is proposed to extend the navigation, by the middle fork, from this place to the mouth of Lewis's Creek, and thence to Staunton. There are five locks, each a hundred feet long, and twelve feet wide; and six canals, each twenty feet in breadth, and four and a half in depth, extending two thousand four hundred yards. The water of all the locks and canals is supplied by the river.The boat navigation of the north, or main branch, of the Potomac, now extends to Western Port, near its source, a distance of two hundred and nineteen miles above tidewater.

The south branch of the Potomac is navigable a hundred miles from its junction with

this river, and the north fork about sixty miles.

The Monocacy, which falls into the Potomac, about fifty miles above the Federal City, is navigable forty miles. The Conegocheague Creek, twenty-four miles. Patterson's Creek, the same distance. The Opechon Creek, twenty-five miles, and the Cape Capeon, twenty.

The boats employed for the navigation of these rivers, are seventy-five feet in length, five feet wide, draw eighteen inches water, and carry twenty tons burthen. Two of them, with more than a hundred barrels of flour each, pass the locks of the great falls in the space of an hour, and it rarely happens that the boat or cargo is injured,

The following comparative estimate has been made of the transportation of a barrel of flour by land and by water, to the tide-water of the Potomac :

From Cumberland, by land.
By water, including tolls
From Williamsburg, by land
By water, including tolls
From Harper's Ferry, by land
By water

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