A turned wooden base supports a three-groove multiple pulley revolving on a horizontal axle. A lead weight is suspended by a cord from each groove. This simple machine, which also illustrates the operating principle of the winch, demonstrates that equilibrium is attained when the sum of the mechanical couples is null. The apparatus was illustrated by Jean-Antoine Nollet in Leçons de physique expérimentale (Paris, 1743-1748). Provenance: Lorraine collections.