1 14 The Drainage of Fens and Low Lands, 



side of the wheel. This can be raised at pleasure 8 feet above the 

 masonry delivery sill, which is lo feet above the tips of the scoops. 

 No portion of the floor is raised with the breast as at Podehole. 

 This breast is so raised and lowered that its crest shall be below the 

 level of the water in the outfall channel a depth equal to one-half 

 the dip of the wheel, this proportion diminishing as it approaches 

 towards the full height to which it can be raised. At a trial made in 

 1872 by Mr. Mason Cooke, superintendent of the district, it was 

 proved that the use of this movable breast added most materially to 

 the efficiency of the wheel. A temporary weir was fixed across the 

 outlet channel at a sufficient distance to allow the water to get well 

 away from the wheel. The crest of this weir was 7 feet 8 inches above 

 the masonry delivery sill, or 17 feet 8 inches above the points of the 

 scoops, equal to a high-flood level in the river. Steam during the 

 trial was kept at a uniform pressure of 5 lb, in the boilers. The dip 

 of the scoops was 3 feet 5 inches, and head 15 feet 11 inches. With 

 the movable breast down the engine was not able to raise the water 

 over the dam, but came to a standstill. The movable breast was 

 then raised 4 feet, when the engine made 10 revolutions a minute; 

 when raised to 5 feet the number increased to 12 ; at 6 feet, to 13 ; 

 at 7 feet, to 13^; and at 8 feet, or 18 feet above the tips of the 

 scoops, the engine made nearly 14 revolutions per minute, and dis- 

 charged over the dam a stream of water 7 feet 6 inches wide by i 

 foot 8 inches deep. A vertical door is fixed on the inlet, which can 

 be raised or lowered by gearing, but this is not used to regulate the 

 inflow of the water, and the wheel is not provided with any adjustable 

 shuttle. The wheel takes up and discharges its water quietly and 

 efficiently, and although necessarily a portion of the water is lifted 

 above the level in the outlet channel, there is no dashing about of 

 the water, but it leaves the scoops freely and in a soHd mass. The 

 wheel is driven by a condensing beam engine, having cylinders 3 feet 

 7 J inches diameter and 8 feet stroke; the steam pressure in the 

 boiler is 20 lb., the pressure before the recent alterations being 5 

 lb. This engine was overhauled and refitted by Messrs. Watt & Co., 

 of Birmingham, in 1881, and adapted to the increased size of wheel. 

 The old cast-iron crank shaft was replaced with a wrought-iron crank 

 with 4 feet throw, a circular slide valve to work from the parallel 

 motion was substituted for the D valve, and an internal expansion 

 valve added to cut-off at from one-tenth to one-half of the stroke, as 

 regulated by a hand-wheel and screw. When pumping at an average 



