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V. — On the Drainage of Haarlem Lake. By Samuel Downing, Esq., LL. D. 

 Professor of Civil Engineering in the University of Dublin. 



Read February 12, 1855. 



X HE Lake of Haarlem, situated in the northern part of North Holland, is (or, 

 we should now more correctly say, was) a large fresh-water lake lying between 

 Leyden and Amsterdam, and reaching within two miles of the city of Haarlem, 

 from which it derives its name. Its general outline is, as appears from the 

 Map, Fig. 1, Plate X., of an irregular oblong figure ; its greatest length, 

 from north to south, being about 14^ miles, and greatest width, from west to 

 east, about 8 miles ; the total area being 44,500 statute acres ; and the average 

 depth 13 feet; the surface of the water was nearly on the level of the sea. 

 Fig. 1 is a map of the Lake, after the boundary dyke and canal had been 

 finished, but before it was finally closed in at Halfwege, Sparndam, and Kat- 

 wyck canal. The dotted lines, within the area of the Lake, show its boundaries 

 at the several dates figured upon them. On the eastern side are shown the 

 minor lakes with which it was feared Lake Haarlem would soon have been con- 

 nected had not it been laid dry. 



Fig. 2 shows the several water-courses excavated in the bed of the Lake, 

 leading the surface water from rain or infiltration to the three pumping-engines 

 by which it is elevated into the surrounding canal, from which it is finally dis- 

 charged into the sea. The bed of the Lake is now laid dry ; the land thus 

 obtained has been sold, and the greater part will this summer produce some 

 kind of crop, a clear addition of about 70 square miles having been thus 

 made to the agricultural resources of that country. 



It is my present object to give some account of the more interesting opera- 



