AGRICULTURE IN 18209, 275 
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insufficient, if the rocks of from : to 4 tons each of which 
it is composed, were cemented together ; by being loosely 
piled, the wave gradually loses its force amongst the 
interstices before it reaches the top, or the upper tiers 
would soon be displaced. The sea damsin Holland, and 
those of Dunjenness and Romney Marsh in England, 
should be the models for those works in Demerara. 
Those of Romney and Dunjenness being on the same 
coast with the breakwater at Plymouth, and subje& to 
the same channel swell, we shall instance more par- 
ticularly. They are composed of rows of oak posts driven 
into the beach, parallel with the coast, at a considerable 
distance from the dam outwards. These rows, tier 
over tier, at intervals of from to to 20 feet, form a 
gradual set of barriers, behind each of which the sand 
and gravel accumulates, till it reaches the high water 
mark on the shore, where a dam becomes perfe€tly 
safe and praéticable. By this method the force of the 
sea becomes gradually weakened, and the base of the 
dam is not only proteéted from the wash, but is strength- 
ened by the deposit left behind each of the rows of 
posts. 
In Demerara this plan is equally praéticable, as it is 
frequently the case where old dams, in spite of constant 
piling, have been washed entirely away, yet these piles 
that were insufficient to save the old dam have saved 
the new one ereéted behind it by a€ting as a breakwater 
in its front. 
FERTILITY OF THE SOIL. 
The powers of vegetation within the tropics are such 
as never fail to astonish travellers from more northern 
regions. The Papaya, in 12 months, will rise 20 feet high 
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