The Foucault's Pendulum demonstrates the rotation of the earth. As the earth turns, the pendulum appears to move around in a circle at 11 degrees an hour, making a full circle in 32.7 hours. Usually, these installations are in museums or the science building of a major university. I haven't ever sat and watched one for 32.7 hours to verify the rotation. I guess I take the rotation of the earth on faith.