Abstract: An apparatus for uniformly, downwardly moving in a vessel a compact bed of solid particles in contact with a liquid. Within the vessel there is provided a rotatable lower disc which has a radially extending opening for the passage of solids therethrough. The lower disc carries a member adjacent the opening for directing solids through the opening during rotation of the lower disc. This member preferably extends above the lower disc. A system is provided to maintain the liquid within the vessel while the solid particles pass out of the bottom portion of the vessel. A rotatable upper disc having a radially extending opening may be present to distribute solids charged to the vessel onto the upper surface of the bed of solid particles.

Abstract: An apparatus for uniformly, downwardly moving in a vessel a compact bed of solid particles in contact with a liquid. Within the vessel there is provided a rotatable lower disc which has a radially extending opening for the passage of solids therethrough. The lower disc carries a member adjacent the opening for directing solids through the opening during rotation of the lower disc. This member preferably extends above the lower disc. A system is provided to maintain the liquid within the vessel while the solid particles pass out of the bottom portion of the vessel. A rotatable upper disc having a radially extending opening may be present to distribute solids charged to the vessel onto the upper surface of the bed of solid particles.

Abstract: Disclosed is a method and apparatus adapted to be used in testing a subscriber line group marker, of a telephone central office switching device, wherein such markers are energizable by application of central office battery potential through a normally open path but closed in response to a subscriber's telephone going off hook and/or an incoming call from a distant office. Testing takes place without removing the marker physically from its central office switching environment by essentially eliminating any chance of it being electrically energizable by anyone but the testing party.