STATIONARY ENGINES.

237

quantity received and discharged may be constantly equal. Thisis considered to be essential when large bodies of water are to bedischarged, or when high velocities are required. The inner surfacesof the discs, or the annular opening around the whole circumference,

Fig. 149.—Arrangement of Centrifugal Pumping Machinery—Gwynne & Co.

has an area equal to the openings at which the water is admittedinto the centre of the revolving wheel. There are two cylindersor water passages, one on each side, with a passage for each inConnection with one suction pipe, rendering the pump extremely