This pump, with twin upright barrels, was made by Nicolas Fortin. The mechanism is contained in a wooden box standing on four legs. There are two unusual features: first, the mechanism is turned upside down; second, the racks—which are connected to the pistons and operated by a crank with three handles—project from the base rather than from the top of the pump. The stop-cocks at the base of the cylinders are automatically opened and closed by the moving crank. The box carries the bell-jar plate. A side-tube was originally connected to a mercury pressure-gauge or manometer. A fairly similar design (but with the mechanism reversed) was developed by Willem Jacob 's Gravesande c. 1720. Provenance: Lorraine collections.