142 The Drainage of Fens and Low Lands. 



be over 300,000/., and that tlie maintenance of the 114 windmills 

 required would amount to over 6000/. a year. The cost of draining 

 by steam-power was estimated at 100,000/., and the annual expendi- 

 ture after the lake was dry at 4500/. Some of the Commissioners 

 came over to England to inspect the steam pumps in the mining 

 districts of Cornwall and elsewhere, and as the result of their inspec- 

 tion recommended a design submitted to them by Messrs. Gibbs and 

 Deane, which was finally adopted. The dimensions of the steam 

 engines and pumps as set out in this design were larger than any 

 that had previously been constructed, and the whole scheme was 

 so novel, and differed so much from anything that had ever been 

 attempted before in Holland, that considerable anxiety was felt by 

 the Commission in incurring so large an outlay. The agreement 

 with Messrs. Gibbs and Deane stipulated that they were to receive 

 a premium of 3000 guilders, whether the machinery succeeded or 

 not; if successful, to have 9100 guilders in addition — making about 

 1000/. — and 200 guilders for each million pounds in excess of the 

 stipulated 75,000,000 lb. of water raised i foot high with 94 lb. of 

 best Welsh coal 



Observations on the rainfall of Holland, extending over a period 

 of ninety-eight years, had shown that the greatest depth of rain in 

 any one month was 6*524 inches more than the evaporation for the 

 same period j i • 47 inches were allowed for infiltration, giving 8 inches 

 to be lifted in one month. The level of the lowest land was 14 feet 

 below A.P., and the water in the drains, after the lake was reclaimed, 

 was settled to be 15^ feet below A. P. The lift into the Ringvart 

 would therefore be, when the pumping was completed, 15 J feet. 

 The lake at 13 feet deep contained 780,000,000 tons of water, 

 which had to be lifted an average height of 16 J feet. The total 

 rainfall and infiltration was estimated at 40,000,000 tons during the 

 works and 60,000,000 tons afterwards. It was calculated that to 

 lift this quantity and afterwards to keep the polder dry, three engines 

 of 350 horse-power each would be required, and it was determined to 

 erect these at the extremities of the lake. These engines were sub- 

 sequently named the Leeghwater, at the south, near Kaag; the 

 Lynden, at the north ; and the Cruquis, near the junction of the 

 canal with the Spaam. It was estimated that, with no delay from 

 accidents, the lake could be laid dry in fourteen months, allowing 

 250 working days in a year. From a variety of causes, and the 

 access of water from infiltration beyond what was anticipated, the 

 tmie actually occupied was thirty-nine months, and the quantity 



