The Harmonograph was originally invented in the 1870s as a means of analysing vibrations, and was particularly useful for the study of sound. By the early 20th century it was regarded as just a scientific toy for drawing patterns such as this example. The device consists of a pen and drawing table mounted on pendulums which are set swinging at right angles to each other. The pen is lowered carefully to the table and traces out the resulting combination of the two vibrations. The pendulums can be made to swing more quickly or slowly by altering the number and position of the weights. Made using a Newton harmonograph of 1909.