PORTS AND TERMINALS 1. Significance of ports.-A port is a place where ocean and inland transportation meet. It presup poses safe anchorage or harbor for the ocean carrier and facilities for the loading and unloading of freight. A port's economic importance depends upon a num ber of factors among which are its geographical loca tion, physical characteristics, relation to ocean routes and nature of its "hinterland" or back country, that from which and for which it receives its freight.
2. Relative importance of world ports.—The fol lowing table gives an idea of the relative importance of the larger foreign and domestic ports. As these figures indicate, the port of New York is by far the most important.
3. Physical characteristics.—Ports may be of three types: river ports, roadsteads, or natural bays. River ports were the first to become prominent. They have many advantages. They are easily accessible both from the ocean and from the land ; they furnish a safe anchorage ; and, since the port is more or less inland, the length of the land haul, always more expensive than water transportation, is shortened.
The main drawback of a river port is the expense of keeping the channel navigable for the ocean ships, which year by year increase in size. The rivers carry down sand, gravel, and clay and deposit this in the river's bed and mouth, thus not only filling the chan nel hut constantly changing its location. This diffi culty is all the greater when the port is located at a long distance from the ocean, as many of the large ports are, New Orleans being 106 miles from the Gulf, Baltimore 151 miles from Hampton Roads, Rotterdam 18 miles from the North Sea, Bremen 54 miles, Hamburg 67 miles and London 67 miles.
Many of the large river ports have, therefore, es tablished subsidiary ports near the mouth of the river. Relatively cheap land could be obtained there for harbor works and the stretch of channel necessary to be kept open for the largest vessels could be greatly shortened. Cuxhaven, Bremerhaven and Tilbury are examples.
The creation of roadstead ports is usually very ex pensive. Breakwaters must be constructed and the basins thus created dredged. None of them is very prominent. The handling of freight is likely to be difficult and costly in such ports. Boulogne in
France, Dover in England and San Pedro in Cali fornia are examples. Boulogne's chief significance is as a passenger port for travellers to and from Eng land. The boats of the Holland-America line call there on eastward voyages.
The natural bay port is of more commercial sig nificance. New York, San Francisco, Boston, and the ports of the Puget Sound are bay ports. The fact that large rivers empty into some of the bays gives them the advantages of both bay and river ports.
4. Port improvements.—The increasing size of ships places a heavy burden on the ports. Channels must be deepened and not infrequently widened to accommodate the modern liners, some of which are 1000 feet in length. Wharves must be constructed to accommodate these ships. With the increase in size of the ships comes an increasing demand for greater speed and efficiency in loading and unloading. Every unnecessary hour spent in port is a loss to the owners.
5. Wharves the tides are mod erate as in New York and San Francisco harbors, ves sels may dock there. Sometimes it is found desirable to construct basins or tidal docks. The Erie Basin and the Atlantic dock at Brooklyn were constructed to afford anchorage outside the regular channel. In the case of the Atlantic dock, 40 acres of low marsh land were dredged, substantial quays built and a series of large warehouses constructed in connection with them. Such basins permit concentrated ownership and control, and a greater concentration of railroad facilities than would be possible if the wharves were spread over miles of river front.
Where the difference in tides is great, say from 12 to 40 feet, as in Liverpool, London, Havre, Mar seilles, Hamburg and Antwerp, it is necessary to close the entrance to the docks by means of locks. Such docks, usually called wet docks, are expensive. They are supplemented at Liverpool and Antwerp by large floating pontoons or "landing stages." Liverpool's largest one is 2,478 feet long and 80 feet wide and is connected with the shore by nine bridges besides a large floating bridge for freight. Seattle has a wet dock with two locks a mile inland.