Blackburn Pendulum No.4


  • Print size 24 x 16in, including 1in white border to accommodate artist signature and edition number.
  • Digital c-type with matt finish.
  • Limited edition of 10 prints

A Blackburn pendulum is a device for illustrating harmonic motion and it was named after Hugh Blackburn who described it in 1844. It is a beautifully simple and graceful machine. 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.

These beautiful images 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 it's 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 it's 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.