a simple, yet ingenius invention from

A harmonograph is a mechanical apparatus that employs pendulums to create a geometric image. The drawings created typically are Lissajous curves, or related drawings of greater complexity. The devices, which began to appear in the mid-19th century and peaked in popularity in the 1890's, cannot be conclusively attributed to a single person, although Hugh Blackburn, a professor of mathematics at the University of Glasgow, is commonly believed to be the official inventor.Turner, S: "Demonstrating Harmony: Some of the Many Devices Used To Produce Lissajous Curves Before the Oscilloscope", Rittenhouse, Vol. 11, Issue 42, page 41, February 1997.