Volume of 96 geometrical patterns. Inserted is a piece of paper with a sketch diagram of a harmonograph.
A machine recognisable as a harmonograph was described by S C Tisley in 1873 to demonstrate the action of two pendulums acting simultaneously. It was manufactured under that name by Tisley and Spiller a few years later. Although used to analyse sound, it became was more popular as a scientific toy. While the image of the pattern could be projected, the usual construction by the end of the century was to attach the drawing table and pen to two separate pendulums, which were then adjusted in frequency, amplitude and phase to give a variety of patterns.