AGRICULTURE IN 18209. 273 
mately conneéted with it as the administration of the 
Funds of the Netherlands is with the Dikes of Holland ; 
without the union the country would cease to exist. 
The praétical drainage of estates is effected by means 
of a sluice or koker with a valve door, opening to the 
sea ; the latter is most simple and common. A wooden 
trough 6 feet square, 24 feet long, with a door of the above 
description, will drain 400 acres, but for a greater extent 
an increased diameter is necessary on account of the ex- 
traordinary accumulation of water during the heavy rains. 
Cast-iron kokers on the same plan, but cylindrical, are 
used with equal effe&, but they are generally of too small 
diameters. A koker should always be large enough to 
prevent any fall of rain from raising the water to the sur- 
face of the earth, as in this instance the light vegetable 
mould, with all its salt, is washed into the trenches, and 
the land becomes impoverished. 
Nothing is so injurious to land as imperfe&t drainage. 
When drainage is entirely stopped, vegetation decays 
and remains upon the surface, and the superabundance 
of water loosens the soil and causes it to imbibe the nu- 
tritious particles. But where land is allowed to be at one 
period overflowed and left dry at another, the very prin- 
ciples of fertility are destroyed altogether. 
It is evident, therefore, that one of the most serious 
duties of a Manager is constant attention to the drainage 
of the estate, and the Proprietor should spare no expense 
in securing this, to secure the fertility of bis fields. 
An empolder is a dam of earth formed by digging a 
trench inside, which circumvents the portion of land 
taken into cultivation. This trench constitutes the main 
drain of the estate, with which all the fields communicate 
