PLATE XX. Fig. 1. represents a side elevation of a steam carriage; and Fig. 2, part of a cross section to double the scale: the same letters refer to the same parts in both. The steam is generated in a cylindrical boiler A, and the fire and flues surround it; it is joined to two cylinders H, H, of the same diameter, intended as reservoirs for steam, and in these are inserted the engine cylinders, G, G'; the parts I, I, form a reservoir of water not exposed to the pressure of the steam, but surrounding the flues and chimney so as to be heated ready for injection into the boiler A by a small force pump. In order to distribute the heat of the fuel so as to render it effective on a larger surface, there are two fire places, with fire doors at B, B', but fed with coals by hoppers from the boxes D, D′; the doors are used only to clear the bars, and should be kept open as little as possible. The fire flues meet at the middle; the one from the fire B' rises at F, Fig. 2, passes along on the upper surface of the cylinder A, round H at M, also round the end of the boiler, and returns on the opposite side, to ascend the chimney in the division E'; the other proceeds in the same manner in the opposite direction, and ascends at E. There are two apertures for air C, C, to each ash pit, both of which should be provided with registers, so that those may be open which either face a strong wind, or (in ordinary cases) those which face the direction of the motion of the carriage. For a like reason the top of the chimney E should have two apertures, that the motion of the air, or the motion in the air, may assist the draught. The engine and boiler are supported by a frame, and this is supported by the axis; but to prevent the carriage resting on three wheels, there may be four spiral springs in the boxes L, L, and the cross heads must be connected to the piston rods by moveable joints, and all the bearings must be formed so as to admit of the motion which would take place by the sinking of one of the wheels in a certain degree. The waste steam passes from the slides to the chimney by the pipes K, and there should be two safety valves, one locked in a box at J, the other open for the use of the engine man at J'. (See art. 266-273.) There will, I think, be some advantage in making the pistons act together, because the effect will be as great as by dividing it, supposing both methods to be perfect; and in acting together there would be less interference of the motion of the one with that of the other. The slide would be best moved from curved teeth on the beams. (See art. 481.) For the proportions and construction of the boiler, (see art. 244, 227, 278 and 522-526 :) for the engines, (see art. 271-380;) and for the power required, (see art. 590.) |