Such considerations as these have a profound bearing on many of the great economic problems of the age, but on none more than upon the grand problem which is now agitating the national mind in the United States: _How to connect its seaboard and central regions by water_. A glance at the map of the Union shows that its vast interior lies ensconced between the two mountain-walls of the Rocky chain on its western side and the Appalachian chain on its eastern side. Hemmed in by these barriers is the immense expanse of the most prolific, populous and prosperous section on the continent, which, taking its name from "the Father of Waters," is geographically designated as the _Mississippi Valley_, estimated by Professor J. W. Foster of the Chicago University to contain an area of two million four hundred and fifty-five thousand square miles, equal to that of all Europe excepting Russia, Norway and Sweden. Unlike the inland basin of Asia, in which the vast, mountain-girt Desert of Gobi stretches out its seas of sand, stony, sterile and desolate, the inland basin of America is its garden-spot and granary. Swept by the vapor-bearing winds and rain-distilling clouds from the Gulf of Mexico, and blessed with an excellent climate, it contains all the physical elements of an empire within itself. Its position makes it the national strong-hold, so that with military men it has grown into an adage, "Whoever is master of the Mississippi is lord of the continent." It is yet but half developed, but no far-seeing mind can form any estimate of its future growth and opulence. "With a varied and splendid entourage--an imperial cordon of States--nothing," says Dr. John W. Draper of New York, "can prevent the Mississippi Valley from becoming in less than three centuries the centre of human power." The only wall of partition that shuts it off from the great marts of the world is formed by the chain of the Alleghanies, which stretch along the Atlantic seaboard, from south-west to north-east, for twelve hundred miles. This natural barrier, with a mean altitude of two thousand feet, is destitute of a central axis, and consists, as the two Rogerses, who have most fully explored its ridges, showed, of a series of convex and concave flexures, "giving them the appearance of so many colossal entrenchments." With a broad artificial channel cut through its sunken defiles and picturesque gorges, there would at once be opened a gateway for the flow and reflow of the heavy commerce of the Western World.