Centrifugal Ptmips, 95 



both Messrs. Gwynne and Co. and Messrs. J. and H. Gwynne 

 have used the other form. 



The following description of a centrifugal pump is taken 

 from a paper read by Messrs. J. and H. Gwynne at the British 

 Association meeting, held at Norwich in 1868, and partly from 

 the patent specification of the pump patented by them xxx 

 1 868. Fig. 3, Plate 4, shows front and side sectional elevation 

 of this pump. The pump consists of an outer case E, with a 

 disc or impeller A, having six arms or blades B cast on a 

 centre boss. A centre plate C springs from the boss and 

 gradually decreases in thickness to a knife edge, bringing the 

 separate currents of water into each side of the disc without 

 producing an eddy or reflux. The arms are radial for two- 

 thirds of the length, and curve off towards the periphery in 

 an opposite direction to the line of rotation, in order to direct 

 the water into the sweep of the case and prevent it rushing 

 against the outer side of the discharge passages. Two rings 

 D — see also Fig. 4 — one at each side of the arms, form the 

 bearing surface. The suction passages F F branch off from 

 the suction pipe G at the point g. The bottom part of the 

 casing E is thinned off to a knife edge, as shown at g^ in order 

 to prevent any obstruction to the water. A space is left 

 between the passage and the case to carry the suction pipes 

 F F over the enlargement of the discharge passage in a 

 straight line to the openings in the centre of the disc A, at 

 which point they curve into the top of the openings. The 

 discharge passage is sprung from the periphery of the disc in 

 the form of a helix or volute, commencing at the top of the 

 case E and gradually increasing till it reaches the full size of 

 the discharge pipe E^ That part of the pump casing E 

 which contains the impeller A is made of the same shape as 

 the profile of the impeller, and similar in section and of just 

 sufficient size to permit the impeller to revolve, the bearing 

 rings D being accurately fitted to the turned recesses in the 

 casing. By this means the usual side plates on the discs of 



