A  Foucault pendulum to show the rotation of the earth

A G-clamp with a ball bearing soldered to the inside of the jaw makes a excellent support for a Foucault Pendulum. It is top hung indoors with the ball bearing resting on a stout razor blade or some other hard surface.  When this type of pendulum is set in motion, the plane of swing is changed after a few hours, as will be noticed if a mark is made on the ground at the time of release. It is, of course, the earth rotating underneath the 'bob' which gives this effect.