large size and especially sturdy construction. The largest stationary steam engines now used in any form are those employed for driving the generators of electric power plants. These large machines are almost universally of the inverted vertical direct-acting type, illustrated in the accompanying plate. A sixth important form of steam engine is the steam-driven air compressor described in the article Air Compressors.
Engines other than stationary fall into one of two great classes, viz., locomotive engines for railways and marine engines for ship propulsion. The traction engine is essentially a locomotive engine designed to run on common roads, and the portable engine is practically a stationary engine and boiler plant of small size mounted on wheels so that it may be hauled from place to place. The growth and construction of the locomotive engine are described in the article Locomotive. Marine engines fall into two separate classes. For paddle-wheel boats the beam engine and the inclined engine are universally employed. For screw-propelled vessels the inverted vertical direct-acting engine is almost universal. (See Steam Navigation.) For a discussion of the theory of steam engines and heat engines in general, see Steam and Thermodynamics. For descriptions of special applications of steam engines, see Automobile; Fire-Engine; Blowing-Machines.
Bibliography. For an account of the development of the steam engine, see Thurston, Growth of the Steam Engine (New York, 1879). Among the best theoretical and descriptive works are: Clark, The Steam Engine (London, 1890); Thurston, Manual of the Steam Engine (New York, 1892); Hutton, The Mechanical Engineering of Power Plants (ib., 1897); Seaton, A Manual of Marine Engineering (ib., 1895); Peabody, Valve Gears for Steam Engines (ib., 1892).
STEAMER DUCK, Loggerhead, or Racehorse. A very large duck (Tachyeres cinerus), numerous about the southern extremity of South America, so called on account of its peculiarity of rowing itself along the surface of the water at great speed. This is said to be due to the remarkable fact that this bird loses its power of flight when it reaches maturity.
STEAM HAMMER. See Hammer.
STEAM HEATING. See Heating and Ventilation.
STEAM NAVIGATION. The Spaniards assert that as early as 1543 Blasco de Garay made an attempt to propel a vessel by steam in the harbor of Barcelona. In the absence of direct proof of the fact this may well be doubted. At the time mentioned the most advanced scientists in Europe had not yet begun seriously to consider steam as a source of power. The assertion is also made that Denis Papin (q.v.) in 1707 propelled a boat by steam on the River Fulda. Papin invented the safety valve and a single-acting steam cylinder pump, and made various improvements in steam pumps, but it does not appear that he ever built what might be called a steam engine. The boat which has been mentioned and which is frequently referred to had some sort of paddle wheels, but they were operated by the crew and not driven by steam power. In 1729 Dr. John Allen took out a patent in England for a method of propelling a boat by means of forcing water out of the stern with steam or other pressure. In 1736 the rather vague ideas of Allen were improved upon by Jonathan Hulls, a clockmaker of Campden, England, and he was granted a patent for mechanism to propel a boat by steam power. Like Allen, he apparently made no serious attempts to put his ideas into practice. In 1752 the French Academy of Sciences awarded a prize to the distinguished physicist Daniel Bernoulli for an essay on the manner of propelling boats without wind. In addition to other suggestions he proposed the use of the screw propeller.
HULLS' BOAT.
(From an old drawing.)
Up to this time successful steam navigation was impossible because a practical steam engine did not exist. This deficiency was supplied by Watt, who took out his first patent in 1769, but the engines contemplated were really single-acting pumps. In 1782, however, Watt brought out the double-acting engine, and developed the principle of expansive working by cutting off the steam at a suitable point instead of allowing it to follow full stroke. All the conditions for the propulsion of vessels by steam were now in existence and experimental boats rapidly appeared. In 1783 the Marquis de Jouffroy built one which was tried at Lyons, and it is said to have been successful; but before it could be developed into a form for practical use the Revolution overtook and ruined him. At the same time John Fitch, James Rumsey, and Oliver Evans were experimenting in America. Rumsey's boats, like the proposed vessel of Dr. Allen, were fitted with jet propellers, whereby a stream of water was discharged by a steam-driven pump. His first boat was tried in Virginia in 1784 and a second, which attained a speed of 4 knots, was completed in 1786. He died in London in 1792, just previous to the trial of a new boat built from his plans. Fitch's boats were fitted with various types of propelling machinery—with paddle wheels in 1785 and afterwards with long paddles which were given motion similar to that of the paddle of an Indian canoe. In 1790 one of Fitch's boats attained a speed of 7 knots, and afterwards was used on the Delaware to carry passengers. In 1793 Filch went to France; in 1796, after returning to America, he built a small screw steamboat, but the exact measure of success that he attained is uncertain. Evans experimented with various peculiar types of steamboats, one of which was fitted with a rude screw and wheels with which to run on shore. In England Joseph Bramah obtained a patent in 1785 for propelling vessels by means of “a wheel with inclined Fans or Wings similar to the fly of a Smoke-jack or the vertical sails of a windmill.” A patent for a similar invention was issued to William Lyttleton in 1784 and to Edward Shorter in 1800. In 1791 John Stevens of Hoboken, N. J., patented a multitubular steam boiler, and he soon after began experiments with steam propulsion of boats, in which he was assisted by the
