The Harmonograph reached the height of its popularity in the late 1800s. I designed and built this one for my sister as a wedding present, it was constructed in stainless steel and aluminium. The drawer underneath holds the coloured pens.
The device consists of two pendulums hanging from a platform or table and both able to swing in 360 degree arcs. Attached to one is a platform to fix the paper to and the other has an arm with a pen on one end and a counterweight at the other.
 Both pendulums are set in motion, the pen is lowered onto the paper and will imediately start to trace out a line. As the pendulums gradually slow down, a fine pattern will emerge. The best results come from having the absolute minimum friction, the pendulums are sitting on sharp points for minimal contact and the good quality pen is weighted just enough to touch the paper. This means the pendulums take longer to slow down and the lines are closer together. Each pattern is unique and depends on how the pendulums were swung at the start.