12 2 The Drainage of Fens and Low Lands. 



river discharges into tire tidal stream from the same main Fen drain, 

 'which is 20 feet wide, with slopes i^ to i. The depth of water at 

 starting the engines is generally about 6 feet 6 inches, decreasing to 

 4 feet 6 inches after the pmnping has been going on. Since the 

 erection of the new engine and pmnp this drain has been found to 

 be too small to keep up a full supply, the inclination on the surface 

 being at the rate of 6 inches in a mile, which is greater than should 

 be the case in a large main engine drain. The height the water has 

 to be raised on an average is lo feet, rising as high as 17 feet in high 

 floods in the river. Steam power was first applied to the drainage of 

 this district in 1832, a 60 horse-power low-pressure condensing 

 engine being then erected by the Butterley Company to drive a 

 scoop wheel 33 feet 6 inches in diameter ; and this engine, with the 

 aid of numerous wind engines previously in use, and retained as 

 auxiliaries, preserved the district from injury fairly well. The con- 

 tinuous subsidence of the surface of the land, and the increased 

 height the water rose in the river, due to the rapidity with which 

 floods now come down from the uplands, rendered this drainage power 

 inadequate. It was found by experience that, owing to the con- 

 stant variations in the levels of the water, both in the main drain 

 and in the river, the scoop wheel became so water-logged and 

 unwieldy, and the loss by leakage so increased by the great head of 

 10 feet to 13 feet, against which it frequently had to work, that, not- 

 withstanding the great prejudice which all Fen men have m favour 

 of the scoop wheel, Mr. Carmichael, the superintendent of the South 

 Level, advised the Commissioners to adopt another form of machine 

 which would adapt itself automatically to the variations of lift, and 

 which, under the varying circumstances of the discharge, would 

 absorb the whole power of the engine to the best advantage, and for 

 this purpose he selected one of the Appold type, which, although 

 they had been in use for some time in other parts of the Fens, were 

 as yet untried in the South Level. The new engine and pump were 

 intended to relieve the old engine of the greater part of its duty, more 

 especially in times of excessive floods, and to drain out the water to 

 a lower level than was practicable with the scoop wheel. The new 

 machinery was erected by Messrs. Easton & Anderson, under Mr,. 

 Carmichael's direction. The engine is a 60 nominal horse-power 

 compound condensing beam engine, supplied with steam at 65 lb, 

 pressure by two Lancashire boilers. The high-pressure cylinder is 

 IS inches, and the low-pressure 25 inches diameter, with 4 feet 



