The photographs displayed in this project show were created by a Blackburn Pendulum in a ratio around 2:1 with exposure times in the region of 17 minutes.
A Blackburn pendulum is a device for illustrating simple harmonic motion and it was named after Hugh Blackburn who described it in 1844. It is a beautifully simple and graceful device. A weight is suspended from a length of wire that in turn hangs from a V-shaped arm. This arm pivots in a perpendicular direction so that the pendulum oscillates simultaneously in two different directions with varied periods. The weight consequently follows a path resembling a Lissajour curve which illustrates harmonic motion.
The images created show the path of light emitted from a small hole in a tin can above a camera. The brighter areas in the picture are created when the pendulum has exhausted most of the energy and is hanging over the camera in roughly the same position. The separated lines toward the edge of the image were created at the start of the pendulum swing when it was at its fastest, as the pendulum slows down over the 17 minute exposure the length of the swings shorten and the distance between the lines in the image become closer.