Friction?

THE TIPPE TOP is a curious gadget that has plagued more than one physicist when pressed for an explanation. A small sphere having a short stem on one end, with the center of gravity of the top being below that of the center of curvature of the sphere, the top is first spun with the stem upright and its center of gravity at its lowest point; but then, apparently in contradiction to all the laws of mechanics, the top wobbles and ultimately turns, over by itself so that it spins on its stem! In the latter position, it will be noted, its center of gravity is at its highest point. This is no trivial problem, having been treated already in the Philosophical Magazine by J. L. Synge and in Physica by C. M. Braams and N. M. Hugenholz.