What is harmonigraph?

A harmonigraph is a mechanical instrument that creates complex and beautiful geometric patterns. It consists of a pendulum, which swings in a specific way to create intricate designs on paper. Harmonigraphs were popular in the Victorian era, when people enjoyed creating art and exploring the realm of science and mathematics. They were often used for entertainment or educational purposes, and were sometimes incorporated into larger machines and contraptions. Today, harmonigraphs are still used as a teaching tool for concepts such as harmonics, resonance, and Fourier analysis. They are also enjoyed as a form of kinetic art, with modern versions created using computer programming and 3D printing.