Of the Regnault apparatus only the pump remains. It is a suction and compressing pump, similar to the one used for liquids, consisting of a single, small diameter pump body in which a piston without a valve is moved up and down by hand.
In the exemplar presented here, the pump body, which is made of brass, is 24 cm in height and has an outside diameter of 3.1 cm. It is attached to a heavy, cast iron support in the shape of a truncated cone painted black which in turn lies on a rectangular wooden base (length 68 cm, width 17.5 cm).
The overall height of the pump is 42 cm. The steel piston has a wooden handle which can be grasped with both hands.
An A and an I printed on the cast iron support in correspondence to the two pipes indicate which is for suction and which for compression.
It is in a good state of conservation.