The great coal companies of the East deliver their coal in similar pockets on the coast, but they transport a large portion of it thence to the consumer by means of tugs and barges. In proportion to the coal carried, the tug-and-barge system costs less than cargo-carrying steamers. The tugs, with their high-priced crews, are kept moving; they tow the barges in "strings" to their destinations, dropping one here and another there, until the last is at the pier. Then they return, picking up the barges that have been unloaded, and take them to the pockets for more coal. The barges have small crews of low-priced men. The expense of waiting for the discharge of the coal is therefore less than if a steamer had carried the coal; it is even less than the expense of a schooner lying thus. The systems of handling cargoes in coarse freight trades of the American coast are, perhaps, the most perfect in the world. Naturally, extensions of the railroad lines have been made across deep water. The Pennsylvania Railroad established the American line from Philadelphia to Liverpool in 1871. The Baltimore and Ohio established the Atlantic Transport line to Europe. The Louisville and Nashville created lines from Pensacola to several countries, including Japan and China. The Illinois Central has lines from New Orleans. The Occidental and Oriental Steamship Company was organized to carry the freight of the Pacific railroads from San Francisco to the Far East. Near the end of the nineteenth century the Southern Pacific Railroad bought an interest in the Pacific Mail. The Northern Pacific was served for years by the Boston Steamship Company, and the Great Northern Railroad built two of the largest cargo carriers in the world for an extension of service across the Pacific. Most of the ships in these extensions of railroads have been of American build. In oversea traffic the through bills of lading and special terminal facilities gave the ships owned by railroads special advantages in the world's traffic. A great corporation is able to purchase supplies at the lowest prices. Further than that, it is not infrequently advisable to carry freight on ships at an actual loss in order to provide freight for the cars in which it can be carried with profit.