In 1851 the French physicist, Jean Bernard Leon Foucault, demonstrated the effect of the Earth's rotation using a pendulum. Now you can do it too, right on your desk! Start by pushing the pendulum in one direction. Wait a little while and examine it again. By this point you will notice it has changed its direction and has written beautifully geometric patterns. The patterns rotate between big and small as the arc of the pendulum also changes. Sand is included with the pendulum and provides minimal friction, thus allowing the pendulum to swing for periods of time.