American. 1920s. Cast iron and brass. This heavy pump has two reciprocating cylinders mounted astride a support with pivoting rocker arms. The steel handle used at the top of the rocker is pushed back and forth actuating the leather ringed piston plungers forcing air up through a non-return check valve and into the diver's helmet. Has not been tested for functionality. Gauge crystal is cracked. Horseless Carriage Museum, Fenelon Falls, Ont. 47 x 29 x 7".