Visual proof of the rotation of the earth was first demonstrated in Paris in 1851 by the noted French physicist, Jean Bernard Foucault, who used a cannon ball for a pendulum and suspended it from the dome of the Pantheon by a wire about 250 feet long.
The pendulum you see at the Besser Museum is suspended from the ceiling above the main floor. A universal joint allows it to swing freely in any direction. A free swinging pendulum cannot change its plane (Newton's Law of Motion) and once started it will continue to swing in the same direction.
The pendulum is kept in motion by an electro-magnet which induces a current that supplies the necessary energy to overcome friction and air resistance to keep it swinging uniformly. Without an external power source, the length of the swing will decrease in a few hours almost to zero.
A pendulum placed at the North or South Pole will complete a 360 degree rotation in a 24 hour period. Alpena is located at the 45 parallel and the time required for the pendulum to return to the starting point is 33 hours and 56 minutes.