A harmonograph is a mechanical device that employs pendulums to create a picture. The drawings created by the machines can be Lissajous curves or even more complex. The devices appeared in the 19th century and are attributed to Jules Antoine Lissajous.

A simple harmonograph uses two pendulums to control the movement of a pen relative to a drawing surface. One pen moves the pen back and forth along one axis and the other pendulum moves the drawing surface back and forth along a perpendicular axis. By varying the frequency of the pendulums relative to one another (and phase) different patterns are created, Even a simple harmonograph as described can create ellipses, spirals, figure eights and other Lissajous figures.

More complex harmonographs incorporated three or more pendulums or linked pendulums together (for example hanging one pendulum off another).