plates, turned into rings, each being welded longitudinally, whilst their transverse junctions one with another are riveted in the ordinary way. The junctions, EE, of the two ends, with fire-box and smoke-box, are formed by angles or flanges welded on, instead of by separate angle irons riveted these were turned and faced in the lathe to a true surface, for the bearing against the fire-box at one end, and the cylinder foundation-plate at the other, thus affording great accuracy in these details. The original idea of welding the boiler-plates is claimed by Mr. Hackworth, who, it appears, had actually made a boiler on this principle long prior to the date of the construction of the "farmer's engine" by Mr. Willis. The example of construction now before us is a very beautiful one; indeed, it is unrivalled as a specimen of this class of workmanship. The lagging, or cleading, of the boiler is covered with sheet iron, giving the surface a smooth appear

ance.

The plate, F, forming the back corners of the fire-box, is 14 inches broad, and was originally made in three pieces for the convenience of setting; but, after the completion of the process, they were welded together, so as to form a single plate. The grate bars, GG, are arranged longitudinally, and are carried on two transverse bearers, supported on projections on a pair of longitudinal shafts, H H, at the bottom of the fire-box, and worked by a lever, 1, standing up from the foot-plate, so that the driver may drop the whole set of bars instantaneously into the ash-box, J. The latter may also be dropped independently of the bars, by releasing the suspending bars, K K, on each side.

The fire-door, L, is provided with a regulator for the admission of air into the fire-box at pleasure, the baffle-plate being perforated with small apertures for its dissemination in the interior. The boiler tubes, м, are of brass, 2 inches in external diameter, and are 221 in number. At the smoke-box end of the tubes a baffle-plate is also fixed opposite the tube ends; it is perforated with holes 1 inch diameter, the under sides of which correspond with the bottom line of the tubes, so that the hotter portion of the vapour is retained at the upper side, inducing a superior evaporative action. This addition does not interfere in any way with the cleaning of the tubes, as it may be removed with great facility. The dome, or steam chest, N, is formed out of a single plate, welded longitudinally, the flange for riveting it to the boiler being worked out of the same plate. The upper flange at o is welded on internally, being turned and faced to form a steam-tight joint with the convex cover, which is similarly formed, and is removable for obtaining access to the boiler.

The pistons also involve some novelties both in design and construction they are made entirely of wrought-iron, with the rods forged on them; so that whilst there is thus a gain in lightness and strength, the dangers resulting from occasional looseness are completely removed. The inner framing, Q, consists of two wrought-iron slabs extending the whole length of the boiler's barrel, and attached at one end to the fire-box by inch angular plates riveted on. The peculiar advantage of this arrangement of frame is, that it yields to the expansion and contraction of the boiler, preserving a constantly uniform length between the cylinder and crank axle, and obviating the very common tendency to work loose, and cause leakage. The frame-plates extend from the centre of the crank axle, so as to counteract the effect of the strain of the engine at the most effective

point; and a stiff connexion is formed with the barrel of the boiler by a strong central transverse plate, riveted on by means of stirrup angle-irons. At the smoke-box end, a foot, or flange, is formed on each frame-plate, for abutting against the tube-plate, to which it is riveted and bolted, the connexions being passed through the cylinder flanges.

The outer framing consists of a wrought-iron slab, 9 inches deep and 1 inch thick, extending the whole length between the buffer bars, the axle guards being forged with it in one piece. The transverse junctionplate, s, forms a very important feature of the engine; it is riveted to the boiler by double angle-irons, and extends across and between the inner and outer frame-plates, forming an effective fixed point for the pressure of the working gear.

The piston-rod motion consists of a pair of slide-bars, TT, attached at one end to protecting flanges cast on the cylinder cover, and at the other to the transverse junction-plate, s. The cross-heads, or motion-blocks, U, each consists of a malleable iron double eye-piece, with a box at the inner end, into which the piston-rod is keyed; and on the upper and lower sides of the double eye are bolted the brass slides, with protecting flanges to guide them on the motion-bars.

The connecting-rods, v, are of a plain rectangular section, and are attached to the cross-heads by a steel pin passing through them and through the double eyes, secured by a nut on the outside. The feed-pumps are placed in a line parallel to the piston-rods. The rams are of malleable iron, passed through and secured by a nut to the cross-head pin. The pumps are of brass; they are attached to the inner frame and transverse junction-plate.

It is an ascertained fact that, in too many cases, very little regard is paid to the obtainment of a sufficient area in the valve-cases for the admission of feed-water to the boiler. Owing to the contraction of this space, the valves are made of small size, and thus a great rise is absolutely necessary to admit a due supply of water; and this, coupled with their great rapidity of action, is frequently the occasion of great inconvenience in point of derangement and wear. Where the contraction exists in excess, the defect is heightened by the absorption of power in forcing the feed through the passages.

In the "Sanspareil," the valves and valve-boxes, w, are made very large, so as only to require th inch lift of valve.

The eccentric sheaves are made with the smaller divisions of wroughtiron, having pins forged upon them, to connect them with the larger or prominent eccentric sides, which are of cast-iron. The eccentric rods and

straps are of wrought-iron, and the rods are forged on the front halves of the straps, the latter being lined with brass. The back halves have an oilvase, x, forged on each, with a syphon-pipe on each side the bolt, for lubricating the sheave. The slide-spindles are guided in brass bearings, in a bracket, y, fixed to the transverse junction-plate; and the bottom of this bracket, at z, forms a bearing for one end of the reversing weigh-bar.

The ordinary link motion is adopted for the slide and reversing gear, the lifting links for reversing being placed inside the motion links, and connected with the forward eccentric pins; and the levers on the reversing weigh-bar are forged on.

The fire-box is at cc, the smoke-tubes at dd, the balanced spring

safety-valve at aaa'; b the steam-whistle; ss the smoke-box; h the blast

M

fig. 154.

supplying steam to one cylinder; o the feed-pipe to supply boiler with water from tank in tender.

In fig. 154 we give the elevation of an American locomotive, with outside cylinders; and in fig. 155 a longitudinal section of the same. сс the fire-box; d d the flue-tubes; ss the smoke-box; ee the conical blast

pipe, the opening of which is regulated by the levers as in the drawing ; m m the steam-dome; n n the steam-pipe; rr the regulator dome; o the regulator, consisting of a spindle-valve, actuated on by the

F

fig. 156.

lever o', admitting steam to the cylinder through the pipe o" o"; ll the steam space above the tubes; pp the lock-up spring safety-valve; ƒ g the funnel; ii, hh, kk, the "spark-arrester." The curved arrows show the direction of the heated air; the sparks being deposited in the curved vessels ii, the heated air and steam passing out at the vertical apertures kk. The eccentric-rods and gear for working the valves, &c. are shown at b b.

In fig. 156 we give a transverse section of same engine at smoke-box end. dd the tubes; e the lever for working the conical blast-tube e e; o