Leon Foucault was a french physicist and was the inventor of the Foucault Pendulum. He was born in Paris, France on September 18, 1819. He studied physics and the Earth's rotation. The Foucault Pendulum was a pendulum that has a heavy weight that is hung by a wire and swings in a constant direction. The Foucault pendulum shows that the Earth rotates. Leon also invented a photometer which measures the brightness of light. This was significant because, it improved the performance of induction coils. His Foucault Pendulum was significant because it demonstrated the Earth's rotation. Leon Foucault died on February 11, 1868. He died in Paris, France.