86 The Drainage of Fens and Low Lands. 



and wheel amounts to as much as 70 per cent of the power 

 applied ; on the other hand, in the best wheels, this has been 

 reduced to 30 per cent. Messrs. Watt and Co., of the Soho 

 Engineering Works, Birmingham, who have had considerable 

 practical experience in the working of scoop wheels, having 

 altered several of the older wheels in the Fenland, and thereby 

 added largely to their efBciency, are of opinion that the merits 

 of the scoop wheels are not sufficiently valued. Having care- 

 fully measured the quantity of water flowing down the feeding 

 drains, and taken the power of the engine as indicated at the 

 cylinder, they have found an efficiency of 75 to 80 per cent, 

 in wheels with flat scoops, worked by beam engines using 

 steam at a pressure of from 20 pounds to 25 pounds on the 

 square inch. The details of one of these trials will be given 

 in the description of the Hundred Foot wheel. Messrs. Watt 

 consider that in a scoop wheel the flow being continuous from 

 the feeding drain to the actual delivery, as good an effect 

 should be obtained in a well-constructed wheel as with a 

 reciprocating pump, where the motion of the water is not only 

 changed in direction, but where frequently masses of water 

 as between the pumps and air vessels or other pipes have 

 to be put in motion. Their experience gained from fitting 

 up a large number of waterworks, leads them to rely on 

 obtaining with such pumps 80 per cent, of effective work. 

 With regard to the loss by leakage, Messrs. Watt entirely 

 disagree with Mr. Airy. They consider that in a well-made 

 wheel the loss from this cause is practically nothing. The 

 head that causes the leakage they consider is only that be- 

 tween the level of the water in one space between the scoops 

 and the level in the next succeeding space, and that the 

 general motion of the wheel and the upward current of the 

 whole mass of water practically overcome the leakage. 

 Further, they consider that in calculating the discharge of a 

 wheel a greater quantity must be allowed for than the exact 

 dip of the scoop, as owing to the velocity imparted to the 



