Centrifugal Pumps. 93 



drainage of land in consequence of the successful trials at the 

 Exhibition. The proprietor of Whittlesea Mere, a large tract 

 of fen and morass, was so satisfied with the performance of this 

 machine that he gave instructions to Messrs. Easton and 

 Anderson, the exhibitors, for the erection of an Appold pump, 

 calculated to discharge 15,000 gallons — sixty-seven tons — a 

 minute to a height of 5 feet. The lift of this pump had sub- 

 sequently to be increased from time to time as the land 

 settled, an operation performed with so little difficulty as 

 to prove the adaptability of the pump for this purpose. A 

 full description of this pumping station will be hereafter 

 given. 



The centrifugal pump is a machine consisting of an outer 

 case having inlet and outlet pipes, in which revolves a fan 

 at a high velocity. This high velocity adapts them well for 

 gearing direct to engines running at high speeds. A very 

 large displacement of water is effected in a short time. The 

 machines are compact and occupy small space. The weight 

 also being about one-twentieth that of a scoop wheel, the area 

 of buildings required is small, and the cost of foundations is 

 very inexpensive compared to those required for wheels. The 

 first outlay is also considerably less. The average difference 

 of cost of the pumping stations erected in Holland during 

 recent years is 20/. per actual horse-power in favour of the 

 pumps. Another great advantage of the centrifugal pump is 

 that it readily adapts itself to the varying lift which must be 

 encountered in most drainage stations, and automatically 

 adjusts the work thrown on the engine as the lift varies. At 

 first starting the engine drain is full, and at its highest level. 

 The lift therefore being smaller, the pump discharges a 

 larger volume of water ; as the water in the drain lowers 

 the lift increases and the quantity pumped diminishes in 

 proportion, giving more time for the water to flow from the 

 distant drains down to the engine drain and keep it fed. If 

 pumping into a tidal stream the same effect takes place ; as 



