XXVIII. J. F. FURN1SS. 



efficiency that was obtained in the trials or at the incep- 

 tion of the installation of a plant, is gradually reduced. 



Electrically driven pumps are specially suited to cases 

 where a considerable number of pumps scattered over a 

 large area are under one control. Centrifugal pumps lend 

 themselves to this class of work, but the consideration of 

 the question of their efficiency being only as, say 62 to 75°/°, 

 they are rejected, although experience has proved that in 

 the space of a few years the pump with the highest effici- 

 ency has virtually become obsolete by the process of 

 attrition. Of course this process will go on in the case 

 of the centrifugal type, but the question of renewal of a 

 pump case or impeller is an easier and less costly matter 

 than renewals of pump barrels, plungers, etc., especially 

 in inaccessible places. 



Centrifugal Punips — Efficiency and Applicability — Single 

 Stage, low heads. — The highest efficiency that has been 

 obtained by these pumps in actual work is 62f , and this 

 only when the impeller and case are in good condition and 

 a perfect fit. The running conditions require close watch- 

 ing, otherwise great loss may occur. Notwithstanding the 

 low efficiency of centrifugal pumps, they have been found 

 especially useful in some services, and in a calculation 

 based on low initial cost compared with other types, they 

 may be considered worthy of adoption, although a difference 

 of 30 l /° efficiency in favour of the other types, would cer- 

 tainly represent a lot of money annually extended over the 

 life of the respective types. 



Excellent results have been obtained with the Reynolds' 

 form of pump, a view of which is shown in fig. 1. This was 

 the first pump introduced to this State; it is capable of 

 raising a large volume of water to a great height, viz., four 

 million gallons to 240 ft. head in 24 hours. 



