New York answers all these requisites better than any metropolis in the world. She has a harbor capable of accommodating all the fleets of Christendom, both commercial and belligerent. That harbor has a western ramification, extending from the Battery to the mouth of Spuyten Duyvil Creek,--a distance of fifteen miles; an eastern ramification, reaching from the Battery to the mouth of Haarlem River,--seven miles; and a main trunk, interrupted by three small islands, extending from the Battery to the Narrows,--a distance of about eight miles more. It is rather under-estimating the capacity of the East River branch to average its available width as low as eighty rods; a mile and a half will be a proportionately moderate estimate for the Hudson River branch; the greatest available width of the Upper Bay is about four miles, in a line from the Long Island to the Staten Island side. If we add to these combined areas the closely adjacent waters in hourly communication with New York by her tugs and lighters, her harbor will further include a portion of the channel running west of Staten Island, and of the rivers emptying into Newark Bay, with the whole magnificent and sheltered roadstead of the Lower Bay, the mouth of Shrewsbury Inlet, and a portion of Raritan Bay. As this paper must deal to a sufficient extent with statistics in matters of practical necessity, we will at this stage leave the reader to complete for himself the calculation of such a harbor's capacity. In this respect, in that of shelter, of contour of water-front, of accessibility from the high seas, New York Harbor has no rival on the continent. The Bay of San Francisco more nearly equals it than any other; but that is on the Pacific side, for the present much farther from the axis of national civilization, and backed by a much narrower agricultural tract. We will not refer to disadvantages of commercial exchange, since San Francisco may at any time be relieved of these by a Pacific Railroad. On our Atlantic side there is certainly no harbor which will compare for area and convenience with that of New York.