io8 The Di^ainage of Fens and Low Lands. 



tions carried out a few years ago. On the inlet side — see Plate 5 

 — a shuttle has been added, by which the amount of water com- 

 ing to the wheel can be adjusted and the supply regulated to the 

 quantity best adapted for keeping the wheel fully charged without its 

 being drowned by it. This shuttle is of the same width as the wheel, 

 and consists of a wooden door fixed across the inlet close up to the 

 wheel, and working on friction wheels in a frame placed in the 

 masonry. The door is fixed close to the wheel, at an angle of 45 

 degrees to the bottom of the raceway. It is provided with a balance 

 weight, hung by a chain working over a pulley. The shuttle is lifted 

 or lowered by a toothed rack gearing into a spur wheel and pinion 

 attached to a shaft, which is carried up into the inside of the building. 

 The floor drops away from the bottom of the shuttle on the inlet side 

 in a circular form, so as to give a larger space for the admission of 

 the water, and allow it to come up and pass freely under the shuttle. 

 The water passing under the shuttle does not catch the scoops until 

 they come towards the bottom of the trough, and then impinges on 

 them in the same direction in which they are travelling, and with a 

 velocity due to the head of water at the back of the door, and thus 

 aiding in the forward motion of the wheel. The scoops become 

 fully charged as they assume a vertical position. The apparent in- 

 crease in the lift from the lower level from which the water has to be 

 raised is more than compensated for by the avoidance of the mass of 

 dead water which a wheel generally has to encounter "on first enter- 

 ing the water, and by the wheel being just sufficiently fed with water 

 having a velocity and direction which assist in sending it round. A 

 much greater quantity of water is thus raised with the same amount 

 of steam than could be done if the shuttle were not there. With the 

 surface of the water in the inlet drain during floods standing 6 feet 

 10 inches above the bottom of the scoops, the shuttle is lifted suffi- 

 ciently to allow I foot 3 inches of water to pass under it, and this 

 keeps the wheel well suppliei A movable breast has also been fixed 

 on the outlet side. It is made of iron plates, and works into a recess 

 cut in the masonry of the breast, so that its face is flush with it. The 

 plates are bent so as to have the same radius as the wheel; the 

 upper part of the segmental plate is hinged at the top into another 

 flat wooden platform fixed to an iron frame, which when down lies in 

 a recess in the floor of the outlet, and rises with the breast. To 

 enable this platform to adjust itself to the space in which it has to 

 lie, it is so formed that one end slides in and out of the iron frame. 



