4 
vation acts as a drainage canal. The outer slopes of the dike should 
have a grade of at least 13 horizontal to 1 vertical and should be shielded 
from wave cutting by being well sodded with the marsh sod. On 
exposed shores, where the wave action may be great. special precaution 
should be taken to prevent washing by waves. The precaution may 
take the form of masonry work or stone facing in the more substantial 
dikes, or it may be a simple brush fence held in place by stakes driven 
in the ground. Various expedients of this nature, both cheap and 
effective, will suggest themselves to the engineer. 
The ditch on the inside of the dike should be designed for drainage. 
This ditch is usually situated along the lowest portion of the marsh and 
is well placed to receive the lateral drains from the higher portions, 
and, being at one end of the field, it is of little obstruction in the way 
of cultivation. The dimensions of this ditch will be governed by the 
amount of material required to construct the dike, if the dike material 
is all taken from the ditch. A mistake is often made by digging the 
ditch too wide. Consideration must also be given to the amount cf water 
emptying into the drains from the entire watershed and to be removed 
in a given time. It is very seldom necessary to remove more than one- 
half of an inch in depth of water in any twenty-four hours, and if the 
ditches are planned to carry this much water the drainage is good. 
Under certain conditions the open ditches should have a capacity of as 
much as one inch in depth over the entire watershed tributary to the 
ditch. The outlet of the main drains should be through the dike by 
means of an automatic sluice or tidal gate. Ample room for storage of 
the drainage water which may accumulate during high tide should be 
allowed and the sluice gates should be of at least twice the capacity of 
the main ditch, so that the entire drainage during high tide may be 
removed during the interval of low tide. 
On exposed coasts, where the maintenance of an outlet would be dif- 
ficult or when the drainage is desired at a level lower than the lowest 
tide, some other means of getting the water over the dike must be 
planned. Windmills have been favored in European countries and have 
been used in a small way in America. Various forms of pumps of 
cheap construction and of great efficiency are now in the market, and 
when driven by steam or gas engines are probably the cheapest form of 
water-lifting machinery and are not dependent upon the vagaries of 
the wind. Such a lifting plant need not be run all of the time, if stor- 
age of the drainage water can be allowed. The conditions are excep- 
tional where the pumping is necessary during the entire growing season. 
UNDERDRAINAGE. 
Tile drains are the most effective means of removing water from land 
and in the course of time will prove the cheapest. Farmers’ Bulletin 
