96 Ward's Steam Engine. 
in Hornblower’s valve : the moveable plate is attached to 
the cylinder, and is turned by it; while the other plate, 
being attached to the centre-piece, remains stationary. 
The steam-tube, after passing from the boiler along the cen- 
tre-piece, arrives at the cocks, and enters one of these sec- 
torial apertures, from the back, in the plate attached to the 
centre-piece. In like manner, the eduction-tube extends 
from the bottom of the opposite aperture in the same plate, 
through the centre-piece, to the condenser ;—or, if the en- 
gine be made without a condenser, the tube terminates in 
the open air, and the steam escapes. A tube extends from 
the bottom of each aperture, in the plate attached to the 
cylinder, to each end of the cylinder, and there enters its 
cavity. The revolution of the cylinder and the moveable 
plate attached to it, brings the aperture belonging to each 
end of the cylinder, alternately to the aperture in the station- 
ary plate, through which the steam enters; while, at the 
same time, the aperture belonging to the other end of the 
cylinder, is passing the aperture belonging to the eduction- 
tube. 
The outer end of the piston-rod is attached to a cross- 
piece, which is supported by gudgeons, moveable in boxes 
in the arms of the water-wheel. From the middle of this 
cross-piece, and perpendicular to it, proceed two wings, one 
on each side, from the ends of which two rods extend, play- 
ing through steps on the sides of the cylinder. These rods 
are necessary in order alternately to overcome the inertia, 
and resist the momentum, of the cylinder, encountered in 
consequence of the irregularity of its motion. 
The operation of this engine is as follows :—The steam, 
by means of the piston, alternately drawing and pressing 
upon the cross-piece, which works in the arms of the water- 
wheel, forces the wheel around, at the same time that the 
cylinder itself is carried round, by reason of its connexion 
with the cross-piece; the reaction being sustained by the 
gudgeons of the cylinder, resting on the centre-pieces. 
Asthe cylinder revolves ona different centre from that of 
the wheel, the radii of its angular motion vary from the 
radii of the wheel, coinciding with them in two opposite 
points only, which is at the moment the engine is passing 
the dead-points. If the revolution of the wheel be supposed 
uniform, the revolution of the cylinder will be irregular, be- 
