An early electrically driven wall clock by Alexander Bain, circa 1850

The three-wheel movement is enclosed by rectangular brass plates, which are united by shouldered tapering pillars. The train is advanced by a lightly sprung pawl, which is connected to the pendulum via a crutch piece and engages with a ratchet wheel. The pendulum rod is a rectangular sectioned strip of painted wood with a central steel contact pin that engages with a sliding contact piece. The two ends of the contact piece rest within grooved ebony discs with gold contacts connecting to the cloth covered wires connected to the power supply. When contact is made the current is passed down the back of the pendulum rod to the coil enclosed within a brass case. The coil passes across a straight brass tube which contains the permanent magnets. Impulse is given to the pendulum on its return from the right-hand side.
The case is veneered with birdseye maple and has a hinged front door with concave moulding to the glazed circular aperture for the nominal twelve inch dial. The pendulum and contacts are visible through a similarly moulded glazed arch on the door.

Alexander Bain (1810-77) is generally considered to be the inventor of the electric clock; he was certainly one of the great nineteenth century pioneers of electrical and telegraphic technology. His first patent in this field dates from 1841.
Though not involved with Greenwich his contribution to horology was fundamentally important to the Astronomer Royal’s, George Biddell Airy’s, system of time distribution, which began in 1852.