DRAINING OF LAKES. 417 
cases where its surface has never been raised above it, pumps, 
worked by wind or some other mechanical power, must be very 
frequently employed to keep the land dry enough for pasturage 
and cultivation.* 
Draining of the Lake of Haarlem. 
The substitution of steam-engines for the feeble and uncer- 
tain action of windmills, in driving pumps, has much facili- 
tated the removal of water from the polders as well as the 
draining of lakes, marshes, and shallow bays, and thus given 
such an impulse to these enterprises, that not less than one 
hundred and ten thousand acres were reclaimed from the 
waters, and added to the agricultural domain of the Nether- 
lands, between 1815 and 1858. ‘The most important of these 
undertakings was the draining of the Lake of Haarlem, and for 
this purpose some of the most powerful hydraulic engines ever 
constructed were designed and executed.t The origin of this 
lake is unknown. It is supposed by some geographers to be a 
part of an ancient bed of the Rhine, the channel of which, as 
there is good reason to believe, has undergone great changes 
since the Roman invasion of the Netherlands; by others it is 
thought to have once formed an inland marine channel, sepa- 
* The elevation of the lands enclosed by dikes—or polders, as they are 
called in Holland—above low-water mark, depends upon the height of the 
tides, or, in other words, upon the difference between ebb and flood. The 
tide cannot deposit earth higher than it flows, and after the ground is once en- 
closed, the decay of the vegetables grown upon it and the addition of manures 
do not compensate the depression occasioned by drying and consolidation. 
On the coast of Zeeland and the islands of South Holland, the tides, and of 
course the surface of the lands deposited by them, are so high that the 
polders can be drained by ditching and sluices, but at other points, as in 
the enclosed grounds of North Holland on the Zuiderzee, where the tide 
rises but three feet or even less, pumping is necessary from the beginning, 
—STARING, Voormaals en Thans, p. 152. 
+ The principal engine, of 500 horse-power, drove eleven pumps with a 
total delivery of 31,000 cubic yards per hour.—WILD, Die Nederlunde, i., 
p. 87. 
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