The apparatus consists of a clear Perspex tube 380mm long
x 50 mm 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 170 x 170x
130 mm 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 3 mm dia
metal spheres and four card board loading discs. Overall dimensions
assembled 170 x 170x 20 high.