(under subclass 328) Apparatus in which a fluid material is utilized for causing motion of the movable member, the principle force applied to movable member being derived from gravitational force exerted thereon by the fluent material (i.e., weight).
(1) Note. Exemplary of apparatus classified under this definition are devices comprising either a movable container or piston within an open ended cylinder which is alternately filled and emptied with liquid, the weight of the liquid causing movement of the container on the piston within the cylinder.
