Pumping Stations, 149 



the former and 96/. for the latter, or a total of 166*84/. per horse- 

 power of water lifted. In 1872 these wheels were changed for wheel 

 pumps — Pofnpradereji — having a width of 5*25 feet, and diameter 

 25*84 feet. The drum was 19*41 feet in diameter. These wheels 

 made from 3-63 to 4*30 revolutions a minute. The number of 

 buckets was originally six, this number being subsequently increased 

 to twelve. At one time buckets were tried, having a curved form 

 with the concavity towards the inner water, and others with the con- 

 cavity towards the outer water. There was not found in working to 

 be much difference in the result between the two systems, but, if 

 anything, the latter gave the best results. The loss by slipping and 

 imperfect filling of the pump wheels was found to amount to as much 

 as 22 per cent, of the theoretical discharge. These pump wheels 

 were recently altered to ordinary wheels having flat scoops, and new 

 engines of the horizontal condensing type have been put up by 

 Friedrich-Wilhelms-Hiitte, of Mulheira. These engines have a stroke 

 of 5 • 25 feet ; cylinder diameter, 3 * 00 feet; I.H.P., 147 each. Steam 

 is used at a pressure of 60 lb., and is cut off at half the stroke. The 

 engines make 16 revolutions per minute to 4 of the wheel. With 

 four wheels at work the discharge is 152*8 tons, lifted to a height of 

 6 feet, equal to 240 water horse-power. The indicated horse-power 

 of the two engines being 294, this gives an efficiency of 81 * 97 per cent 

 The scoops are tangents to a circle having a diameter of 11 • 16 feet. 

 The outer diameter of the wheel is 26 feet; the inner diameter and 

 length of scoops, 4*23 feet. The scoops are twelve in number, made 

 of wood ; the framing of the wheel being iron. With the scoop fully 

 immersed, the discharge at each wheel is 43* 88 tons per revolution, 

 or 175*52 tons per minute, and for the six wheels 1053*12 tons. 

 With an immersion of 3 feet the discharge is reduced to 33*22 tons 

 per revolution. The two engines use at the rate of half a ton of 

 coal per hour, which, with an effective power of 240 water horse- 

 power, is equal to 4* 67 lb. per hour. 



BuLLEWijKER PoLDER, HOLLAND. — This machinery was put up 

 in 1 88 1 by Messrs. J. and H. Gwynne ; it is of a similar type to that 

 erected by this firm elsewhere, and is capable of raising 60 tons a 

 minute. The lift is 14 feet— 4*67 metres; maximum discharge, 

 2508 cubic feet per minute — 1*184 cm. per second; coal consumed 

 per W.H.P. per hour, 5*22 lb. — 2*37 kilogs. ; ratio of water to 

 indicated horse-power, 58 per cent. The trials from which these re- 

 sults were obtained were made by Mr. Elink Sterk, the engineer 



