o the valve rod, which is moved by the contact of the arm
_e_, on the piston rod with said tappets--_h_, the double-acting water
plunger working through a packing ring--_o, o_, force valves--_o', o'_,
suction valves. The pump piston is represented as moving from right to
left, the arrows indicating the course of the water through the passages.
The suction valves _o'_, on the right side, and the force valves _o_, on
the left side, are show open; _x_, is an air chamber made of copper; _s_,
the suction pipe terminating in a vacuum chamber; made by prolonging the
suction pipe, and closing it perfectly tight at the top, the connection
being made to the pump by a branch as shown; _m, m_, are hand-hole plates,
affording easy access to the water valves; _n, n_, small holes through the
plunger, which relieve the pressure near the end of the stroke, to give
momentum to throw the valves when working at slow speed.

[Illustration: Fig. 63.]

Fig. 63 is a perspective view of H.R. Worthington's Duplex Steam Pump. The
prominent peculiarity of this pump is its valve motion. As seen in the cut,
two steam pumps are placed side by side (or end to end, if desired). Each
pump, by a rock shaft connected with its piston rod, gives a constant and
easy motion to the steam valve of the other. Each pump therefore gives
steam to and starts its neighbor, and then finishes its own stroke, pausing
an instant till its own steam valve, being opened by the other pump, allows
it to make the return stroke.

This combined action produces a perfectly positive valve motion without
dead points, great regularity and ease of motion, and entire absence of
noise or shock of any kind. Both kinds of pumps are made by Mr.
Worthington, of various size according to the requirements, the duplex
being used for boiler feed and for the supply of cities with water.

Fig. 64 is a side elevation of the Woodward Steam Pump. The pump is direct
acting. The steam and water piston being on the same rod, but momentum is
obtained to throw the valves by means of a fly wheel, placed beyond the
pump, and connected with the piston rod by a cross head and a yoke. The
machine is simple in its construction and action, and is extensively used.

Giffard's Injector, both in Europe and this country, is quite extensively
used to supply the place of a pump, as independent feed for all classes of
boilers. It is represented in elevation and section, figs. 65 and 66.

[Illustration: Fig. 64.]