This apparatus was described by Jean-Antoine Nollet in Leçons de physique expérimentale (Paris, 1743-1748) to introduce the study of levers. It is also used to illustrate the conditions of stable equilibrium.
A column holds a curved brass handle fastened to a gilt wooden statue of Mercury (lacking arms). The system can move freely without falling even though it rests on a metal point. The reason is that the handle is designed to consistently maintain the system's center of gravity below its resting point on the support. Small toys based on the same principle, representing tightrope walkers and jugglers, were once quite popular and are still widely available. Provenance: Lorraine collections.