549, COAST OF THE NETHERLANDS. 
Netherlands and the adjacent states have protected a consider- 
able extent of coast from the encroachments of the sea, and 
have won a large tract of cultivable land from the dominion of 
the ocean waters. The immense results obtained from the 
operations of the Tuscan engineers in the Val di Chiana, and 
the Maremma have suggested the question, whether a different 
method of accomplishing these objects might not have been 
adopted with advantage. It has been argued, as in the case of 
the Po, that a system of transverse inland dikes and canals, wpon 
the principle of those which have been so successfully em- 
ployed in the Val di Chiana and in Egypt, might have elevated 
the low grounds above the ocean tides, by spreading over them 
the sediment brought down by the Rhine, the Maes, and the 
Scheld. If this process had been introduced in the Middle 
Ages, and constantly pursued to our times, the superficial and 
coast geography, as well as the hydrography of the countries in 
question, would undoubtedly have presented an aspect very 
different from their present condition; and by combining the 
process with a system of maritime dikes, which would have 
been necessary, both to resist the advance of the sea and to 
retain the slime deposited by river overflows, it is, indeed, possi- 
ble that the territory of those states would have been as exten- 
sive as it now is, and, at the same time, somewhat elevated 
above its natural level. 
The argument in favor of that method rests on the assump- 
tion that all the sea-washed earth, which the tides have let fall 
upon the shallow coast of the Netherlands, has been brought 
down by the rivers which empty upon those shores, and could 
have been secured by allowing those rivers to spread over the 
flats aud deposit their sediment in still-water pools formed by 
cross-dikes like those of Egypt. 
But we are ignorant of the proportions in which the marine 
deposits that form the soil of the polders have been derived 
from materials brought down by these rivers, or from other 
more remote sources. Much of the river slime has, no doubt, 
been transported by marine currents quite beyond the reach 
