el; every part of the governor is finished bright, except the bracket
carrying the lever, and the square base of the standard, which are painted.
The pulley is from 3 to 10 inches in diameter, and makes in the larger
sizes about 125 revolutions, and in the smaller 230 revolutions per minute;
the higher speed of the governor being got up by gearing.

Mr. Porter warrants the following action in this governor, operating any
regulating valve or cut-off which is in reasonably good order. The engine
should be run with the stop-valve wide open, and, except the usual oiling,
will require no attention from the engineer, under any circumstances, after
it is started, until it is to be stopped. No increase in the pressure of
steam will affect its motion perceptibly. The extreme possible variation in
the speed, between that at which the regulating valve will be held wide
open, and that at which it will be closed, is from 3 to 5 per cent., being
least in the largest governors. This is less than 1/6 of the variation
required by the average of ordinary governors, and is with difficulty
detected by the senses. The entire load which the engine is capable of
driving may be thrown on or off at once, and one watching the revolutions
cannot tell when it is done. The governor will be sensibly affected by a
variation in the motion of the engine of 1 revolution in 800.
Notwithstanding this extreme sensitiveness, or rather by reason of it, it
will not oscillate, but when the load is uniform will stand quite, or
nearly, motionless.

For the supply of the water to the boiler, in many positions, it is very
convenient to have a pump unconnected with the engine. On this account it
is very usual in this country to have what are called donkey pumps or
engines independent of the main engines, which can be used to feed the
boilers, or for supplying water for many other purposes.

Fig. 62 is a longitudinal section of the Worthington Steam Pump, the first
of its kind, and for many years in successful operation.

The general arrangement is that of a Steam Cylinder, the piston rod of
which, carried through into the water cylinder and attached directly to the
water plunger, works back and forth without rotary motion, and of course
without using either crank or fly wheel.

[Illustration: Fig. 62.]

In the figures, _a_ is the Steam Cylinder--_b_, the Steam Chest--_d_, a
handle for regulating the steam valve--_f_, the starting bar _g, g_,
tappets attached t