th of
pinions are usually called), C will have 64 teeth and D 60, in a clock
of which the scape-wheel turns in a minute, so that the seconds hand may
be set on its arbor prolonged to the dial. A represents the pallets of
the escapement, which will be described presently, and their arbor a
goes through a large hole in the back plate near F, and its back pivot
turns in a cock OFQ screwed on to the back plate. From the pallet arbor
at F descends the _crutch_ Ff, ending in the _fork_ f, which embraces
the pendulum P, so that as the pendulum vibrates, the crutch and the
pallets necessarily vibrate with it. The pendulum is hung by a thin
spring S from the cock Q, so that the bending point of the spring may be
just opposite the end of the pallet arbor, and the edge of the spring as
close to the end of that arbor as possible.

We may now go to the front (or left hand) of the clock, and describe
the dial or "motion-work." The minute hand fits on to a squared end of a
brass socket, which is fixed to the wheel M, and fits close, but not
tight, on the prolonged arbor of the centre wheel. Behind this wheel is
a bent spring which is (or ought to be) set on the same arbor with a
square hole (not a round one as it sometimes is) in the middle, so that
it must turn with the arbor; the wheel is pressed up against this
spring, and kept there, by a cap and a small pin through the end of the
arbor. The consequence is, that there is friction enough between the
spring and the wheel to carry the hand round, but not enough to resist a
moderate push with the finger for the purpose of altering the time
indicated. This wheel M, which is sometimes called the minute-wheel, but
is better called the _hour-wheel_ as it turns in an hour, drives another
wheel N, of the same number of teeth, which has a pinion attached to it;
and that pinion drives the _twelve-hour wheel_ H, which is also attached
to a large socket or pipe carrying the hour hand, and riding on the
former socket, or rather (in order to relieve the centre arbor of that
extra weight) on an intermediate socket fixed to the _bridge_ L, which
is screwed to the front plate over the hour-wheel M. The weight W, which
drives the train and gives the impulse to the pendulum through the
escapement, is generally hung by a catgut line passing through a pulley
attached to the weight, the other end of the cord being tied to some
convenient place in the clock frame or _seat-board_, to which it is
fixed by s