The Foucault Pendulum

We visited Preston today and went into the Harris Museum, in there they have a Foucault pendulum. When the pendulum swings freely it continues in the same plane in relation to the sun. However the Earth is moving underneath it, so over a period of time the pendulum appears to turn. The real rotation of the Earth causes the apparent rotation of the pendulum. The experiment was demonstrated for the first time in Paris in 1851 by the physicist Jean Bernard Leon Foucult.