848 DRAINING OF THE LAKE OF HAARLEM. 
overflowed twenty thousand acres of land at the southern ex¬ 
tremity of the lake, and flooded a part of the city of Leyden. 
The depth of water did not, in general, exceed fourteen feet, 
but the bottom was a semi-fluid ooze or slime, which partook 
of the agitation of the waves, and added considerably to their 
mechanical force. Serious fears were entertained that the lake 
would form a junction with the inland waters of the Legmeer 
and Mijdrecht, swallow up a vast extent of valuable soil, and 
finally endanger the security of a large proportion of the land 
which the industry of Holland had gained in the course of 
centuries from the ocean. 
For this reason, and for the sake of the large addition the 
bottom of the lake would make to the cultivable soil of the 
state, it was resolved to drain it, and the preliminary steps for 
that purpose were commenced in the year 1840. The first 
operation was to surround the entire lake with a ring canal 
and dike, in order to cut off the communication with the Ij, and 
to exclude the water of the streams and morasses which dis¬ 
charged themselves into it from the land side. The dike was 
composed of different materials, according to the means of sup¬ 
ply at different points, such as sand from the coast dunes, earth 
and turf excavated from the line of the ring canal, and floating 
turf,* fascines being everywhere used to bind and compact the 
* In England and New England, where the marshes have been already- 
drained or are of comparatively small extent, the existence of large floating 
islands seems incredible, and has sometimes been treated as a fable, but no 
geographical fact is better established. Kohl (Inseln und Marschen Schles- 
wig-Holsteins , iii, p. 309) reminds us that Pliny mentions among the 
wonders of Germany the floating islands, covered with trees, which met 
the Roman fleets at the mouths of the Elbe and the Weser. Our author 
speaks also of having visited, in the territory of Bremen, floating moors, 
bearing not only houses but whole villages. At low stages of the water 
these moors rest upon a bed of sand, but are raised from six to ten feet by 
the high water of spring, and remain afloat until, in the course of the sum¬ 
mer, the water beneath is exhausted by evaporation and drainage, when 
they sink down upon the sand again. 
Staring explains, in an interesting way, the whole growth, formation, and 
functions of floating fens or bogs, in his very valuable work, Be Bodem van 
