148 The Drainage of Fens and Low Lands, 



simply to move the machines, the following being given as the result 

 of trials:— 



Consumption ot coal in lb. 

 Lift in feet. Per horse-power per 



hour m water lifted. 



0*45 50*0 



0*66 to 1*00 14*20 



i-ootoi-33 i^'^° 



1-33 to 1*66 ^'^^ 



2-O0t02'28 5*5^ 



The discharge of these wheels varies from 154 tons per revolution 

 when the water is low in the canal, to 230 tons when it is at its 

 highest. These wheels ran 3623 hours during the emptying of Lake 

 Haarlem, the average lift being 20 inches. The average power 

 exerted in water lifted was 92 horse-power, and consumption of coal 

 at the rate of 9 lb. per horse-power per hour. The total quantity of 

 water raised was 202,765,406 tons. The time the engines ran 

 for the three years after the lake was dried— May ist, 1853, to July 

 ist, 1856— was 3675 hours, equal to an average of fifty-one days 

 a year. 



Katwijh—^\it combined machinery at Katwijk is the largest in- 

 stalment of pumping machinery erected in Holland or England. 

 The arrangement and construction of the wheels is similar to that at 

 Halfweg. The wheels are capable of lifting 2000 tons per minute to a 

 height of 4 feet, or 1200 tons to a height of 7 feet. On the discharge 

 side the floor of the raceway immediately in front of the wheel is 

 made movable and hinged at the outer end, so that it rises and falls 

 automatically according to the height of the water, and so makes a 

 movable breast and prevents the back current on to the wheel when 

 it is working. The height to which the wheels have to lift the water 

 varies daily with the tidal condition of the sea from a few inches to 

 7 feet. The variation on the inside is small, never altering more 

 than about 18 inches. The average time of working is about sixty 

 days of twenty-four hours in the year. 



Gouda,—T^t six wheels here are all ranged in two sets on one axle. 

 When the station was first erected the wheels had flat scoops, and 

 were driven by a high-pressure condensing horizontal engine, having 

 an effective power of iii W.H.P., made by the Atlas Company at 

 Amsterdam. The wheels were each 5*75 feet wide and 24-27 it^t 

 in diameter. The consumption of coal with this machinery was at 

 the rate of about 6 lb. per W.H.P. per hour. The cost was 7863/. 

 for buildings and 10,666/. for machinery, equal to about 70*84/. for 



