350 
EXPLANATION OF THE PLATES. 
PLATE XX. 
Fig. 1. represents a side elevation of a steam carriage, and Fig. 2. part of a 
cross section to double the scale r 1 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 11 
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 
opposide 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 yalves, one locked in a box at J, the other open for 
the use of the engine-man at J'. See art. 266—273. 
1 This drawing is, through some oversight, not accurately double in all its parts; and in the 
parallel motion of Fig. 1. the vibration of the beam is not bisected ; see page 233, note.