Harrison's "going-barrel." Larger ratchet-wheel, to which the click, R, is attached, is connected with the great wheel, G, by a spring, S, S'. While the clock is going, the weight acts upon the great wheel, G, through the spring ; but as soon as the weight is taken off by winding, the click, T, whose pivot is set in the frame, prevents the larger ratchet from falling back, and so the spring, S, S', still drives the great wheel during the time the clock takes to wind, as it need only just keep the escapement going, the pendulum taking care of itself for that short time. Good watches have a substantially similar apparatus.