52 The Drainage of Fens and Low Lands. 



II '3 feet and 12*3 feet, and also at a height varying from 

 4 '9 feet to 13 • I feet. To the first question the Commissioners 

 were not able to give an opinion as to whether one form of 

 pump was superior to all others for a high but nearly constant 

 lift The answer to the second question was decisively in 

 favour of centrifugal pumps, as they found that no other 

 machine applied itself so well to differences of level in the 

 external and internal water.^ No other machine permitted the 

 application upon so large a scale of the whole disposable 

 motive force to all lifts comprised within the limits stated ; 

 and thus while the machine adapted for a maximum lift will 

 with lower lifts discharge larger volumes, the useful effect 

 which is produced by the coal consumed does not vary to any 

 great extent They therefore recommended centrifugal pumps 

 for both kinds of work* 



Subsequently, in 1877, Signer Cuppari, an Italian engineer, 

 spent a considerable time in Holland visiting the different 

 pumping stations and investigating this subject The con- 

 clusion he finally arrived at was that no general rule can be 

 given as to the employment of one or other of the different 

 machines, but that all the circumstances of each case must be 

 considered before a decision is come to as to what machine to 

 use.* That the general opinion of Dutch authorities was that 

 in choosing a machine, consideration should be given to the 

 following circumstances, and the machine chosen which met 

 these requirements best : the turbidity of the water ; the pro- 

 bability of the internal water level being permanently lowered ; 

 the nature of the foundations ; the method of establishing 

 communication between the inner and outer water level ; the 

 level at which the machine can be placed with reference to the 

 water to be discharged ; the cost of erecting and working. 

 That the centrifugal had the advantage in all these cases, 

 except the first, over all other machines. That scoop wheels 



* Cuppari *0n Water Raising Machines.* Trans. Inst. C. E., vol. kxr 

 1883-84. 



