Mr. Downing on the Drainage of Haarlem Lake. 457 



every barrier up to the very streets of Leyden, causing loss of life, of cattle, and 

 property; nor were the damages repaired for more than a twelvemonth. 



The Government now at last resolved to complete the work so long pro- 

 jected. A Commission was formed to report upon the plan to be followed, and 

 a credit granted by the States-General. The first of the engineering works of 

 the drainage were more directly connected with the security of the basin of 

 the Rynland than with the Lake itself, and consisted in widening and straight- 

 ening the canal leading to the Katwyck sluice. This canal had been originally 

 formed (in 1806) about 90 feet wide ; it was now made to be 170, which involved 

 the lengthening of the bridges, and increasing the number of the inner line of 

 the sea sluices at Katwyck; the outer line has not been altered. On the north 

 side, the River Sparn was deepened and improved, and an engine of 200 horse- 

 power erected to discharge water from the basin into the Y, when the flow 

 of it outwards was otherwise impossible. Additional sluices were also con- 

 structed at Halfwege, and quite recently, a second engine of 100 horse-power 

 has been put up here, like that at Sparndam, which was found insufficient by 

 itself to keep down the surface of the basin. 



The first direct operation of the laying dry the bed of the Lake was (as is 

 always necessary when gaining new polder land) to completely surround it with 

 a large and water-tight dyke, to separate it from all other waters of the basin ; in 

 this lake it was, moreover, required to provide for that inland navigation which 

 had been hitherto maintained over its waters, and thence up the several chan- 

 nels leading to all parts of the basin of the Eynland. A navigable canal, called 

 the Ringvart, was, therefore, directed completely round the Lake, its inner 

 bank being the surrounding dyke, and the outer formed of the stuff cast out of 

 the canal bed, which had a width of 140 feet, and depth suited to vessels draw- 

 ing 8 feet of water, such as were used in the former navigation of the Lake. 

 Transverse sections of the Ringvart at two different points are shown in 

 Figs. 3 and 4, Plate X. The length of this canal was about 36 miles. 



As to the kind oi jMioer to be used in extracting the water, namely, whether 

 wind or steam, the Commissioners having rejected the idea of using the ancient 

 windmills of the country, or wind with steam as an auxiliary working the 

 scoop-wheel shown in the annexed woodcut, adopted the designs of Messrs 

 Gibbs and Deane, which had been obtained by three of their body, deputed to 



