steam coil

A steam-pipe bent into a shape to occupy the bottom or sides of a boiler, so as to have a large surface in compact space. Used in lard tanks, malt-vats, vacuum-pans, . steam-colors, s . pl . A style of calico-printing in which a mixture of dye extracts and mordants is topically applied to cloth, while the chemical reaction which fixes the colors to the fiber is produced by steam. steam-crane, subst. A crane worked by a steam engine; it frequently carries the engine upon the same frame. IMG:content-0248.png:[blocks in formation] driving-wheels, which are sometimes eight or nine feet in diameter. The number of wheels is six, eight, and in some cases twelve, there being two, four, or six driving-wheels coupled together. The engine can be controlled, stopped, and reversed by a link arrangement (invented by Stephen son), which acts on the slide-valves. The weight of a locomotive is not unfrequently more than sixty tons, and the speed attained is more than seventy miles an hour can do is usually estimated in horse-power (q.v.), but the value of this unit varies. The nominal or into the air by opening suitable valves. The non condensation of the steam and the method of working steam expansively can only be satisfactorily employed with high-pre ure engines, in which the pre ure of the steam is several times greater than that of the atmosphere; the early engines of Newcomen and Watt were low-pre ure engines, in which the pre ure of the steam was not very much greater than that of the atmosphere. The e ential of a modern steam-engine are: The steam boiler, usually called the boiler, in which the steam is generated. It is made of wrought-iron plates, sufficiently thick to resist considerably more than the highest pre ure which they will be called upon to bear, and the form of the boiler is designed to secure the greatest po ible economy of heat. The boilers of locomotives, and of those of many sta tionary engines, are traversed by a large number of tubes, along which the gases from the fire pa ; and in steam fire-engines the boiler consists of a series of comparatively narrow tubes filled with water, this being the form which enables steam to be got up with the greatest rapidity. The height of the water and the pre ure of steam in the boiler are indicated by gauges, of which there are several forms. In order to prevent the pre ure rising too high, each boiler is fitted with one or more forms of safety-valve (q. v.). The cylinder is made of cast-iron, carefully bored on the inside; and the piston (q. v.) is a circular plate of iron packed closely into the cylinder by means of metallic rings. The piston-rod is usually steel, and pa es out of the cylinder through a stuffing-box, in which it is packed steam-tight, either by greased tow or by metallic-rings. The cylinder is provided with a steam-jacket, or outer casing, in which steam circulates; or is covered with some non-conducting material, in order to prevent lo of heat and consequent condensation of steam. The distribution of steam, or its admi ion above and below the piston, is controlled by a slide-valve (q. v.), working in a small cylinder or valve-casing attached to the cylinder. According to the arrangement of these principal parts, distinctive names are applied to steam engines. [BEAM-ENGINE, HORIZONTAL STEAM-ENGINE, OSCILLATING-ENGINE, VERTICAL ENGINE.] They are also cla ified according to their uses, as Portable, Stationary, Locomotive, Marine, Pumping, . In order to overcome the difficulty of the dead-points (q. v.), the fly-wheel was adopted by Watt in his engines, and has been used ever since. [FLY-WHEEL.] In engines which have no fly-wheel the same end is attained by hav. ing two cylinders, working on the same shaft, but with their cranks at right angles. The speed at which an engine works depends on the resistance which it has to overcome; and where this resistance steam-cylinder, s . Steam-eng.: The chamber within which the piston is continually varying, as it generally is, the speed reciprocates. [PISTON.] steam-dome, 8. [STEAM-CHAMBER, 1.] steam-dredger, s. [DREDGING-MACHINE.] steam-engine, s. Steam & Mech.: An apparatus for converting heat into work. The first steam-engine of which we have any account is the eolipile (q. v.). The Marquis of Worcester (about 1601-1667) described a steam-engine in his Century of Inventions, but no practical result followed. In 1698 Captain Savery described his engine for raising water, and this was the first actually used. The principle had been described by Papin a few years previously [DIGESTER, II.], and was applied by Newcomen, who, in conjunction with Cawley, invented the first self-acting engine in 1712, and used it for working pumps, . It consisted of a cylinder in which there was a circular disc or piston fitting tightly, but capable of being moved up and down. Attached to the center of the piston was a vertical shaft or piston-rod; and a stout beam, turning about a center, was attached at one end by a chain to the piston-rod, and at the other end by a chain to a pump-rod. Steam was admitted to the cylinder at the bottom, and the piston rose, the pump-rod being pulled down by a counterpoise attached to that end of the beam. When the cylinder was full of steam, the supply was cut off, and cold water was injected into the cylinder. The steam was thus condensed, and the pre ure of the atmosphere acting on the top of the piston drove it down, raising the opposite end of the beam, and with it the pump-rod. In 1763 James Watt invented the method of the engine will also vary. It is nece ary, how ever, to keep the speed as uniform as po ible, and this is done partly by the fly-wheel, and partly by the governor. [GOVERNOR, II., 2.] In locomotive and other engines where fly-wheels or governors are not used, the speed is regulated by means of an arrangement for varying the time at which the steam is cut off by the slide-valve. [COMPOUND STEAM-ENGINE.] About 1784, Watt patented, but did not actually construct, a locomotive, and Mur doch made a small high-pre ure engine, the fly wheels of which, nine and a half inches in diameter, were used as driving-wheels. Trevithick con structed a high-pre ure locomotive in 1802, and Blenkinsop and Chapman also made locomotives a few years later. The oldest locomotive in existence, Puffing Billy , now in the Patent Museum, South Kensington, was constructed in 1813, and was continually used until June 6, 1862. In 1814, Stephen son constructed the Killing worth Engine, which he continually improved, and, in 1829, won the prize offered by the directors of the Liverpool and Manchester Railway, with his engine, Rocket . In this he used two cylinders placed one on each side of the engine, and acting on cranks attached to large driving-wheels. The boiler was traversed by a number of narrow tubes, as proposed by Seguin and Booth. In modern locomotives, the boilers are of the tubular form, and the engine is driven by two, or occasionally four, cylinders, which in England are placed in front under, but in this country at the sides of the boiler. The waste steam from the cylinders is discharged through a pipe in the chimney of the engine, and creates the draught for the boiler. The two cylinders act on cranks on the axle of the boil, boy; pout, jowl; cat, cell, chorus, chin, bench; go, gem; thin, this; is not 33,000 foot pounds, as on land, but more than 44,000 foot pounds, and in this country its value is still greater. The efficiency of an engine is generally determined by an apparatus in which the pre ure of the steam and the motion of the engine are made to trace a curve on paper by a suitable ar range ment of mechanism. [INDICATOR, II., 3.] steam exhaust-port, s . [EXHAUST-PORT.] steam fire-engine, s. [FIRE-ENGINE, 1.] steam-fountain, s. A jet or body of water raised by the pre ure of steam upon the surface of the water in a reservoir. steam-gas, 8. [SUPERHEATED STEAM (q. v.).] steam-gauge, s. An instrument attached to a boiler to indicate the pre ure of steam. There are many varieties. The oldest and simplest consists of a bent tube partially filled with mercury, one end of which springs from the boiler, so that the steam rising in the tube forces up the mercury in proportion to the amount of pre ure. Bourdon's consists of an elliptical copper tube bent into an arc of 540°. One of the extremities communicates with the boiler or reservoir of condensed gas whose pre ure is to be measured, and the other carries an index which moves backward or forward on a graduated arc as the curvature of the tube is varied by changes of pre ure. steam-governor, 8. [GOVERNOR.]