Drainage by Steam Power, 55 



To show that considerable difference of opinion still exists 

 as to the comparative merits of scoop wheels and cen- 

 trifugal pumps, attention may be drawn to the fact that 

 recently in the same number of the * Engineer,' an account was 

 given in one part of the paper of the removal of centrifugal 

 pumps which had been erected in Egypt by an English firm 

 for lifting the water for irrigation purposes, and the substitu- 

 tion under the direction of a French engineer of scoop wheels ; 

 and in another part, of the intended removal of scoop wheels 

 erected by Dutch makers for the drainage of land in the 

 north of Italy, and a substitution of centrifugal pumps by 

 English makers, because similar pumps working in the same 

 neighbourhood had satisfied the authorities that they were the 

 more efBcient machines. 



Having paid considerable attention to this subject, and 

 had frequent opportunities of becoming acquainted with the 

 working of both machines, the conclusion arrived at by the 

 author is that, with regard to existing wheels, where a scoop 

 wheel can be made efficient at a reasonable outlay, it would 

 be more economical to adapt it than to replace it by a centri- 

 fugal pump. If the wheel requires replacing, or great expense 

 has to be incurred in altering the masonry and foundations 

 and lowering the wheel, it will be found more economical to 

 replace it with a centrifugal pump. In all new drainage dis- 

 tricts in this country, there can be no doubt that the direct 

 acting centrifugal pump is the most efficient and economical 

 machine to fix. 



Engines used for Driving Wheels and Pumps.— In 

 the early attempts to drain land by mechanical means wind 

 power was entirely resorted to. In Holland, where this 

 source of power is largely applied for driving machinery, the 

 numerous windmills and pumps all over the country show 

 that steam has not yet succeeded in displacing the more 

 economical, if less efficient, source of power. Many of the 

 old windmills driving scoop wheels still remain in use in the 



