Two pendulums painting beautiful shells

What is it about?

The oscillations of pendulums can be recorded in a mechanical apparatus called harmonograph (harmonía “harmony”, graphein “to write, draw”).

The harmonic motions of the pendulums lead to beautiful geometric images.

Details and Theory

The drawings are typically Lissajous curves or related drawings of greater complexity. Our harmonograph uses three pendulums to control the movement of a pen relative to a drawing surface. Two pendulums move the pen back and forth along two axes and the other pendulum moves the drawing surface mounted on a gimbal, which allows movement in any direction. By varying the frequency and phase of the pendulums relative to one another, different patterns can be created including ellipses, spirals, figure eights and shell-like structures.