74 The Drainage of Fens and Low Lands. 



there are two or more start posts, the boards being placed in 

 the opposite direction. These boards are called indifferently 

 ''scoops," "ladles/' *' floats," "paddles," the former term being 

 adopted for use in this book, as that most generally in use. 



The axle in the old wheels is carried on bearings resting on 

 the masonry of the trough, the gudgeons having no means of 

 adjustment, and are generally unnecessarily large, increasing 

 the friction. In more modern wheels the gudgeons are kept 

 in their place either by a shoulder running close against the 

 plummer blocks or by screws bearing against the ends. The 

 trough in which the wheel revolves is made of masonry, 

 carried up as high as the centre of the wheel. The invert is 

 made to the same radius as the wheel. The clearance, or 

 space between the wheel and the trough at the sides and 

 bottom, varies from -^ inch in the best machines to f inch, 

 and even more, in the older ones. Owing to the large dia- 

 meter of the wheels and their great weight, it is necessary 

 that the foundation should be rigid and the wheel very nicely 

 adjusted, as the slightest settlement causes the wheel to grind 

 against the sides. Even with thorough adjustment there is 

 always loss of water, owing to the space which must be left 

 between the wheel and the masonry. In order to prevent this 

 loss, some wheels have rims or shroudings on the sides, which 

 partially or wholly enclose the water. The latter are termed 

 wheel pumps. If only partially shrouded, only a portion of 

 the leakage is stopped, and, if wholly, a difficulty arises in 

 providing for the escape of the air contained in the space 

 between the two scoops, which consequently do not become 

 fully charged. 



The scoops are generally flat boards bolted to the start 

 posts and dripping from the radial line at an angle varying 

 from 25 to 55, but generally about 40 degrees, the scoops 

 being set out in tangents to a circle concentric with that of 

 the wheel. The angle at which the scoop enters the water is 

 termed the angle of ingress, being that which the face of the 



