The steam engine familiarly explained and illustrated; with an historical sketch of its invention and progressive improvement; its applications to navigation and railways; with plain maxims for railway speculators. By the Rev. Dionysius Lardner ... With additions and notes by James Renwick ...

fLC)-6'1BTHE STEAM1 EiGINE-.
means of this strap the rotation of the fly wheel will produce
a rotation of the wheel M and the shaft L, and the speed of
the one will always increase or diminish in the same proportion as the speed of the other. N, N are two heavy balls
of metal placed at the ends of rods, which play on an axis
fixed on the revolving shaft at o, and extend beyond the axis
to Q Q. Connected with these by joints at Q Q are two
other rods, q R, which are attached to a broad ring of metal,
moving freely up and down the revolving shaft. This ring
is attached to a lever whose centre is s, and is connected by
a series of levers with the throttle valve T. ~ When the speed
of the fly wheel is much increased, the spindle L is whirled
round with considerable rapidity, and by their natural tendency* the balls N N fly from the centre. The levers which
play on the: axis, o by this motive, diverge from each other,
and thereby depress the joints q Q, and draw down the joints
ia, and with them the ring of metal which slides upon the
spindle. By these means, the end of the lever playing on s
is depressed, and the end v raised, and the motion is transmitted to the throttle valve, which is thereby partially closed,
and the supply of steam to the cylinder checked. If, on the
contrary, the velocity of the fly wheel be diminished, the
balls will fall toward the axis, and the opposite effects ensuing, the supply of steam will be increased, and the velocity
restored.
The peculiar beauty of this apparatus is, that in whatever
position the balls settle themselves, the velocity with which
the governor revolves must be the same,t and in this, in fact,
* The centrifugal force.
t Strictly speaking, this is only true when the divergence of the rods from
the spindle is not very great, and, in practice, this divergence is never sufficient
to render the above assertion untrue. This property of the conical pendulum
arises from the circumstance of the centrifugal force, in this instance, varying
as the radius of the circle in which the balls are moved; and when this is the
case, as is well known, the perzodic time is constant. The time of one revolution of tile balls is equal to twice the time in.which either ball, as a common
pendulum, would vibrate on the centre, and as all its vibrations, though,the