The Foucault Pendulums in this listing are both ideally sized to be placed on a desk and will trace intricate patterns in the sand when the pendulum is set in motion. It's mesmerising and relaxing to watch the swinging of the pendulum! Who Invented the Foucault Pendulum? It's perhaps crazy, but true that a man named Foucault invented the Foucault Pendulum! This happened a long time ago in 1851 and the experiment he created was intended to provide a demonstration of the rotation of the Earth. The pendulum (or "bob") will rotate on a singular plane and over time the Earth shifts underneath the pendulum which creates the wonderful patterns that you can see in the sand. Even today with all of the high tech gadgets around us, this simple pendulum experiment is still mind boggling and intense to watch. You can visit large scale Foucault Pendulums in museums all over the world. Alternatively, you can have your own Foucault Pendulum for your desk at work or at home Product Specifications: Metal Model Dimensions: Height 40cm Metal and Wood Model Dimensions: Height 55cm, Tray diameter approx 23cm Pendulum swings for approx 5 minutes. Includes instructions and sand in a zip lock bag