82 The Drainage of Fens and Low Lands. 



When the height is greater than this, centrifugal pumps are 

 more efifective and economical in working. Before the intro- 

 duction of pumps, where the lift was great, it was usual to 

 divide it into two, and to employ a double set of wheels, one 

 working at some distance behind the other. 



In 1872 a patent was taken out by Mr. G. Hamit, the 

 superintendent of the Haddenham Drainage District, to 

 meet the case of alterations required in existing wheels 

 owing to the subsidence of the soil. By his proposal he 

 claimed to save the expense of increasing the diameter of 

 an existing wheel with the consequent lowering to the 

 masonry of the trough. His invention is described as con- 

 sisting of "the application of an auxiliary wheel at the 

 entrance to the wheel race to feed the water to the scoop 

 wheel, the efficiency of which is moreover increased. This 

 auxiliary wheel is provided with curved blades and is rapidly 

 rotated, the water being admitted to it through a sluice pro- 

 tected by a grating" — Patent specification, 3764, 1872. So 

 far as the principle is concerned, there is nothing new in this, 

 as examples of double lifts already existed in the Fens. 

 The object sought could be obtained more efficiently by 

 lengthening the scoops, as has been done in Deeping Fen 

 and other places. The existing machinery of the old wheels 

 being well and strongly constructed, is easily adapted to the 

 increased work by simple alterations, and by using steam at 

 a higher pressure. By judicious alterations to the engine 

 and wheel a large saving of coals may be effected, and the 

 engine rendered capable of dealing with the increased 

 work 



The greatest quantity of water raised by scoop wheels, so 

 far as the author's knowledge goes, is at Atfeh. At Katwijk, 

 the six wheels raise each over 333 tons, or a total of 2000 

 tons a minute 4 feet high, or 1200 tons 7 feet high. The 

 greatest quantity of water lifted at one station in England is 

 at Deeping Fen, the larger wheel raising 300 tons a minute 



