Pendulum for qualitative and quantitative demonstration of the rotation of the earth by means of observing the plane of oscillation.
To prevent the oscillation taking an elliptical path, the thread upon which the pendulum bob is suspended impinges on a Charron ring during each oscillation. The plane of the oscillation is detected with high accuracy by projecting the shadow of the thread onto a protractor scale. The rotation of the plane can thus be identified in a very short period of time. For longer periods of observation, the gradual damping of the oscillation can be compensated for by means of an electro-magnetic boost that can be adjusted to an arbitrary value.
The apparatus is presented in decorative fashion inside a box with all sides made of glass that is lit from inside to make for a very eye-catching appearance.