Note 319 — Chapter IV

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 enclosed, 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.