In the following table is given the number of miles of surface for each mile of railway in some of the principal States:-- Square miles of surface for each mile of railway. Massachusetts 7 New-Jersey 22 New-York 28 Maryland 31 Ohio 58 Georgia 76 When it is considered that the railways in this country have cost upon an average about 40,000_l._ per mile, the comparatively low cost of the American railways will doubtless appear extraordinary. This circumstance, however, is explained partly by the general character of the country, partly by the mode of constructing the railways, and partly by the manner of working them. With certain exceptions, few in number, the tracts of country over which these lines are carried, is nearly a dead level. Of earthwork there is but little; of works of art, such as viaducts and tunnels, commonly none. Where the railways are carried over streams or rivers, bridges are constructed in a rude but substantial manner of timber supplied from the roadside forest, at no greater cost than that of hewing it. The station houses, booking offices, and other buildings, are likewise slight and cheaply constructed of timber. On some of the best lines in the more populous States the timber bridges are constructed with stone pillars and abutments, supporting arches of trusswork, the cost of such bridges varying from 46s. per foot, for 60 feet span, to 6_l._ 10s. per foot for 200 feet span, for a single line, the cost on a double line being 50 per cent. more. When the railways strike the course of rivers such as the Hudson, Delaware, or Susquehanna--too wide to be crossed by bridges--the traffic is carried by steam ferries. The management of these ferries is deserving of notice. It is generally so arranged that the time of crossing them corresponds with a meal of the passengers. A platform is constructed level with the line of railway and carried to the water's edge. Upon this platform rails are laid by which the wagons which bear the passengers' luggage and other matters of light and rapid transport are rolled directly upon the upper deck of the ferry boat, the passengers meanwhile going under a covered way to the lower deck. The whole operation is accomplished in five minutes. While the boat is crossing the spacious river the passengers are supplied with their breakfasts, dinner, or supper, as the case may be. On arriving at the opposite bank the upper deck comes in contact with a like platform, bearing a railway upon which the luggage wagons are rolled; the passengers ascend, as they descended, under a covered way, and, resuming their places in the railway carriages, the train proceeds.