Rotation of the earth

Ever since the time of Copernicus, it had been assumed that the Earth rotates on its axis, but no one had proven it. Foucault suspended a large iron ball inside the dome of a large church. The pendulum ended in a spike that would mark the floor as it swung, showing the changing orientation of the swing.
 Jean-Bernard-Léon Foucault France 1851 Rotation of the earth

Ever since the time of Copernicus, it had been assumed that the Earth rotates on its axis, but no one had proven it. Foucault suspended a large iron ball inside the dome of a large church. The pendulum ended in a spike that would mark the floor as it swung, showing the changing orientation of the swing.