The view that has been taken so far is sufficient to demonstrate, that the prosperity of the towns in the United States is dependant upon their trade, and principally upon that which is carried on with the interior parts of the country; and also, that those towns which are most conveniently situated for the purpose of carrying on this inland trade, are those which enjoy the greatest share of it. It is now time to examine more particularly how far the situation of the federal city is favourable, or otherwise, for commerce: to do so, it will be necessary, in the first place, to trace the course of the Patowmac River, on which it stands, and also that of the rivers with which it is connected. [Sidenote: PATOWMAC RIVER.] The Patowmac takes its rise on the north-west side of Alleghany Mountains, and after running in a meandering, direction for upwards of four hundred miles, falls into the Chesapeak Bay. At its confluence with the bay it is seven miles and a half wide; about thirty miles higher, at Nominy Bay, four and a half; at Aquia, three; at Hallowing Point, one and a half; and at Alexandria, and from thence to the federal city, it is one mile and quarter wide. The depth of water at its mouth is seven fathoms; at St. George’s Island, five; at Alexandria, four; and from thence to Washington, seven miles distant, three fathoms. The navigation of the Patowmac, from the Chesapeak Bay to the city, one hundred and forty miles distant, is remarkable safe, and so plain that any navigator of common abilities, that has once sailed up the river, might venture to take up a vessel drawing twelve feet water without a pilot. This could not be said of any other river on the continent, from the St. Lawrence to the Mississippi. In its course it receives several large streams, the principal one of which falls in at the federal city. This river is called the Eastern Branch of the Patowmac; but it scarcely deserves that name, as it extends no more than thirty miles up the country. At its mouth it is nearly as wide as the main branch of the river, and close to the city the water is in many places thirty feet deep. Thousands of vessels might lie here, and sheltered from all danger, arising either from freshes, or from ice upon the breaking up of a severe winter. Thus it appears that the federal city is possessed of one essential qualification for making it a place of importance, namely, a good harbour, from which there is a ready passage to the ocean; it will also appear that it is well situated for trading with the interior parts of the country. [Sidenote: WATER COMMUNICATIONS.]