A pendulum with a bob describing a horizontal circle, used in some Victorian novelty clocks and also to control the driving mechanism of equatorially mounted telescopes. The pendulum is normally driven at its lower end by a slotted arm which allows the pendulum to move away from the central position which it occupies when the clock is stopped. The time taken for one circle to be completed is the same as that required for one complete cycle of a normally oscillating pendulum of equivalent length.