6. Dependence on Amplitude of the Oseilation Period of Gravity Pendulums

The period of oscillation T(α) of a gravity pendulum when it swings with amplitude a is usually given by T(α)=T(0)(1+1/(16)α^2). Experiments with our four pendulums with carefully polished steel knife-edge on agate seat do not follow this law, and in order to get consistent results, the coefficient of α^2 must he about 1/10 instead of 1/16. This points to the finite radius of curvature of the knife-edge which is as large as a few cm