The Ocean Carrier and Its Development.—On the ocean, as well as on the land, rapid changes are taking place in the mechanism and services of transport and these changes are affect ing industrial and commercial conditions on a wide scale. The wooden sailing vessel gradually gave way to the steel steamship during the first three quarters of the 19th century. Fulton's "Clermont" inaugurated steamboat navigation on inland water ways in 1807 ; the "Royal William" made the first transatlantic voyage solely by steam power in 1833 ; the screw propeller was invented in 1836; and the iron hull dates from about 1840. The Inman line adopted the propeller in 185o, and the Cunard line in 1862. The "Great Eastern," the giant of its time (1869), had not only a screw propeller, but paddle wheels, and six masts for sails. Twin screws were first used on warships in 188o and on a passenger vessel in 1888. Steel began to take the place of iron in hull construction about 1880.
The relatively slow technical development of the ocean vessel was largely due to the limitations of the marine engine. The engines with low steam pressure and consequently long slow piston stroke could be used to drive paddle wheels by direct crank shaft action, whereas gearing and loss of power were involved in giving the propeller the requisite speed. While direct acting engines were used to drive propellers as early as 1854, it was after 1870 that the present type, the inverted, direct acting, compound steam engine came to be exclusively used; then the ocean vessel developed rapidly in speed, size and economy of service. The conspicuous, much advertised passenger liners at tracted most public attention, but their influence was small in comparison with that of the slow freight steamers, often called "tramps," which after 1870 could move cargo so cheaply as to make possible the shipment, for practically any distance, of bulk cargoes of grain, coal, ore, lumber, phosphate rock and the other essentials of industrial expansion.
The ocean vessel and ocean transport are undergoing revolu tionary changes, due to the invention of the internal combustion engine, the use of oil for fuel, and the operation of freight vessels less as individual units and more in line services with scheduled sailings. The turbine, which had been invented in 1883-84, was introduced in warships and large high speed ocean vessels about 19oo; but while the turbine was superior to the reciprocating engine for some purposes, its use did not involve a fundamental change such as accompanied the introduction of the internal combustion engine named after its inventor, Rudolf Diesel. The Diesel engine does away with the boilers and furnaces, it occupies less space than steam equipment and thus adds to available cargo capacity. It consumes much less fuel, gives a vessel a much greater sailing range and is more economical to operate. For these reasons it is being so largely adopted for
vessels of moderate size and speeds that ocean shipping promises to be motorized in large part in the relatively near future. The check upon the general Dieselization of shipping thus far has been the higher cost of installation and the weight of the Diesel engine and its auxiliaries, but these handicaps are being steadily overcome by designers and builders.
When the motor-bus appeared on the city streets a few years ago, the electric railways were supplying all organized urban transport, and supplemented by suburban extensions they had in three decades, by providing rapid transit, caused cities to spread out over ever enlarging areas and had done much to improve living conditions for the constantly increasing number of people who live in cities. The importance of the interurban electric railway has been greatly reduced by the rapid develop ment of motor-bus service. Many interurban, and also suburban electric lines have ceased to operate in the United States, and in most countries the suburban and local passenger traffic of steam railways, especially in the United States, has been greatly reduced mainly by the extensive use of private automobiles and also by the competition of motor-buses. Indeed local and short distance passenger transport seems to be steadily transferred from the steam and electric railways to the highways.
At the beginning of this century it was thought that steam railways would be electrified, there being no question as to the general superiority of electricity as a motive power, but electri fication has thus far been confined mainly to tunnels, to eliminate the smoke and gases, to a few large city terminals, also for the same reason, and to some mountain grade sections where electric locomotives are more efficient than steam and where current can usually be obtained from water-power. The general electri fication of steam railways in the near future is not probable for the reason that the cost of the change would so increase the investment in the railways as to make impossible a profitable rate of return on the increased capital. Moreover, the steam locomotive has of late improved rapidly in power, efficiency and economy and has made electrification seem less important than formerly. The application of the Diesel engine has great possi bilities.