Notes: "This is a 2-wheel integrator, measuring area and moment but not moment of inertia. Unusually, the rail is included and there is space in the box for it. The box appears to accommodate rails of two lengths, and this is the short one. Ott's serial number, 40234, is engraved on one of the recording mechanisms, and the original owner, ""DVL"", has engraved their inventory number, A7/028279, on the same recording mechanism. DVL has also marked that number on a plaque attached to the box above the keyhole. "