134 ^he Drainage of Fens and Low Lands. 



worked on an average 1800 hours each year, and the engines con- . 

 sumed about 350 tons of coal The pump on the North Reclama- 

 tion, which drains 2489 acres, ran on the average 1516 hours, and 

 the engines consumed 215 tons of coal each year. Taking the 

 average hft throughout the year in both cases as 5 feet 6 inches, and 

 coal at iSi-. per ton, this gives 26*3^. per acre per annum for the 

 scoop wheel, and 18*45^. for the pump for coal only, or per acre 

 per foot of lift 4' 82^. and 3*35^. respectively. 



Ferrara Marshes, North Italy. — This pumping station con- 

 tains one of the largest combinations of centrifugal pumps for the 

 drainage of land yet suppHed. The machinery was erected in 1873 

 by Messrs. J. and H. Gwynne, for pumping the water from the Terrara 

 Marshes in North Italy. The reclaimed land extends over an area of 

 nearly 200 square miles, and the work done by the pumps consists in 

 raising a little over 2000 tons of water per minute for a mean lift of 

 7 feet 6 inches — the maximum being 12 feet — and delivering it into 

 the river Volano, at Codigoro. The machinery consists of four pairs 

 of centrifugal pumps having vertical discs, each set driven by a pair of 

 compound engines. Each pump is constructed to deliver 9150 cubic 

 feet— 255 tons — a minute, or a total for the eight machines of 2040 

 tons. The pumps are placed one on each side of the engines, the 

 pump shafts forming prolongations of the crank shaft, and being con- 

 nected to the latter by disc couplings. The pump shafts are of steel, 

 %\ inches diameter, and are provided with bearings beyond the pump 

 casings. The pumps have discs 5 feet 9 inches diameter, with 

 delivery pipes 54 inches diameter, and double-suction pipes, in area 

 jointly equal to the delivery pipes. The casing of each pump 

 is made in a single casting, 15 feet diameter. The engines have 

 cyhnders 27I inches and 46f inches diameter, the stroke being 

 2 feet 3 inches ; both cylinders are jacketed. For some years after 

 the starting of these machines the low-pressure cylinders of each 

 engine exhausted into a pair of surface condensers, placed on the dis- 

 charge pipes. These condensers were cylindrical chambers traversed 

 by a number of 3-inch tubes, connected with the pump casing and 

 discharge pipe. It was suggested that the efficiency of the pumps 

 was interfered with by the presence of these surface condensers in 

 the delivery pipes. They were removed, and condensation by injec- 

 tion, with auxiliary air-pumping engines, substituted. The alteration 

 was, however, a doubtful improvement, the difference in efficiency 

 was not very observable, and the auxiliary engines involve extra 



