alternately pulled away from and pushed towards
a permanent horseshoe magnet. Currents are thus induced in a bobbin of
fine wire placed between the poles of the horseshoe magnet. The
movements of the armature are produced by another horseshoe magnet
actuated by the primary current from a battery which is turned on and
off by the swinging of the pendulum. The energy of the induced current
that drives the clock depends solely on the total movement of the
armature, and is independent of whether that movement be executed slowly
or rapidly, and therefore of the strength of the battery.

[Illustration: FIG. 32.--Hope Jones Electrical Remontoire.]

_Electrical remontoires_ possess great advantages if they can be made to
operate with certainty. For they can be made to wind up a scape-wheel
just as is done in the case of the arrangement shown in fig. 16 so as to
constitute a spring remontoire, or better still they can be made to
raise a weight as in the case of the gravity train remontoire (fig. 15)
but without the complications of wheel-work shown in that contrivance.
Of this type one of the best known is that of H. Chesters Pond. A
mainspring fixed on the arbor of the hour wheel is wound up every hour
by means of another toothed wheel riding loose on the same arbor and
driven by a small dynamo, to which the other end of the mainspring is
attached. As soon as the hour wheel has made one revolution (driven
round by the spring), a contact switch is closed whereupon the dynamo
winds up the spring again exactly as the train and fly wind up the
spring in fig. 15. These clocks require a good deal of power, and not
being always trustworthy seem to have gone out of use. A contrivance of
this kind now in use is that patented by F. Hope Jones and G.B. Bowell,
and is represented in fig. 32. A pendulum is driven by the scape-wheel
A, and pallets B B in the usual way. The scape-wheel is driven by
another wheel C which, in turn, is driven by the weighted lever D
supported by click E engaging the ratchet wheel F. This lever is centred
at G and has an extension H at right angles to it. J is an armature of
soft iron pivoted at K and worked by the electromagnet M. D gradually
falls in the act of driving the clock by turning the wheels C and A
until the contact plate on the arm H meets with the contact screw L at
the end of the armature J, thus completing the electrical circuit from
terminal T to terminal T' through the electromagnet M, and throu