The apparatus consists of a clear perspex tube 250mm long x 50mm outside diameter provided with a light, freely sliding expanded polystyrene piston and a loose fitting metal cap. The tube is mounted by means of a bayonet-type fitting in a metal cap, upon a polished wood motor housing 165 x 140 x 75mm high. A low voltage d.c. motor is contained in the housing and is coupled to a crank-driven agitator. The push rod of the agitator carries a light plastic piston which oscillates in the lower end of the tube. The apparatus is supplied complete with a supply of 3mm dia metal spheres and one thermocoal loading discs.

Overall Dimensions assembled 165 x 140 x 340mm high.