A wooden frame resting on four legs carries four axles fitted with pinions and reduction cogwheels (i.e., that reduce the motion by an order of magnitude according to a determined ratio). The topmost axle is fitted with a handle; the lowest axle carries a drum around which is wound a cord bearing a lead weight. The model illustrates the ratio between the wheels' complete revolutions and those of the pinions. The ratio determines the force to be applied to the handle in order to lift the weight applied to the system. Provenance: Lorraine collections.