72r The Drainage of Fens and Low Lands. 



the water is pumped out of the drains, or on the outside due 

 to the rise and fall of the tide, or of flood waters in non-tidal 

 streams. As the angle at which the scoops enter and leave 

 the water seriously affects the working of the wheel, even in 

 the best constructed machines, there must always be a loss 

 due to variation in the level The unnecessary height to 

 which some part of the water must be lifted also throws 

 undue work on the engines, although it is not so regarded by 

 all enginemen. Sir G. B. Airy mentions a case of a wheel 

 which he visited, the attendant on which took considerable 

 pride in his wheel because it lifted the water well up into the 

 air, regardless of the fact that the steam power by which all 

 this water was tossed in the air had to be paid for, and was 

 so much waste of power.* There is also loss from leakage of 

 the water between the wheel and the sides and bottom of the 

 masoniy trough in which the wheel revolves. In the event of 

 the surface of the land drained lowering — a frequent occur- 

 rence — it becomes necessary to deepen the drains and lift the 

 water from a lower level, involving the lowering of the wheel, 

 or the lengthening the scoops, and reconstructing the masonry 

 breast of the course, an expensive and difHcult work, owing to 

 the foundations being generally built upon piles. 



Most of the old scoop wheels employed in the drainage of 

 land are unnecessarily wasteful of power. Sir G. B. Airy, the 

 late Astronomer-Royal, who examined one of these machines 

 at work, for the drainage of a large district in the Fens, was of 

 opinion that four-tenths of the power applied was wasted, a 

 great part of which might have been saved by a proper 

 arrangement of the parts, in which opinion he was confirmed 

 by Sir W. Cubitt Many of the wheels do not give off a useful 

 effect of more than 30 per cent of the power applied. 



They are, however, in some case capable of improvement. 

 By alterations recently effected in the engines and wheels 

 used for the drainage of Deeping Fen, more than double the 



* Tians. Inst. C.E., vol. xxxii. 



