A, B, E, F is a frame connected by C, D, a crossbar, through which runs g, a pendulum hung on a pivot, C. This pendulum has two arms, one, a, measuring five feet, and the other, b, one foot in length, connected so together to form a lever I with a long and short arm, whose fulcrum is c.
This pendulum has a weight of two pounds at its end. K, K are two short levers having a joint in them to allow the pendulum to pass them one way, but not the other, without moving them, whose fulcra are d, d, by which they are connected with A, B. From these run cords, l, l, over pulleys, m, m, which cords are connected (for the purpose of drawing them up into catches) with h, h, springs throwing with a power of three pounds. I, I are catches for the springs when brought back after working their power. N is the point where the pendulum, g, will escape from the lever K.
From: Gardner D. Hiscox, M.E., Mechanical Appliances and Novelties of Construction (1927), Norman W. Henley Publ. Co.