These pictures, drawn by a harmonograph, may better be described as pictures of music. A harmonograph is a mechanical device that uses pendulums that move pen and paper simultaneously to create these images. The device was invented by a mathematician in 1844 and apparently was a popular form of entertainment at Victorian soirees.
The images vary depending on how the pendulums swing in relation to one another. Harmonic ratios used in music such as 3:2, 4:3 give the images below.