e of the field,
connecting the heads of the laterals, is to be a stone and tile drain,
such as is described on page 60, intended to collect the water which
follows the surface of the rock. (See Fig. 4.)

The swamp is to be drained by itself, by means of two series of laterals
discharging into the main lines _F_ and _G_, which discharge at the
outlet, by the side of the main drain from the silt-basin. By this
arrangement, these laterals, especially at the north side of the swamp,
being accurately laid, with very slight inclinations, can be placed more
deeply than if they ran in an east and west direction, and discharged into
the main, which has a greater inclination, and is only two and a half feet
deep at the basin. Being 3-1/2 (3.50) feet deep at the outlet, they may be
made fully 3 feet deep at their upper ends, and, being only 20 feet apart,
they will drain the land as well as is possible. The drains being now laid
out, over the whole field, the next thing to be attended to is

*The Ordering of the Tile.*--The main line from the outlet up to the
silt-basin, should be of 3-1/2-inch tiles, of which about 190 feet will be
required. The main drain _A_ should be laid with 2-1/4-inch tiles to the
point marked _m_, near its upper end, as the lateral entering there
carries the water of a spring, which is supposed to fill a 1-1/4-inch
tile. The length of this drain, from the silt-basin to that point is 575
feet. The main drain _C_ will require 2-1/4 inch tiles from the silt-basin
to the junction with the lateral, which is marked _C_ 10, above which
point there is about 1,700 feet of drain discharging into it, a portion of
which, being a stone-and-tile drain at the foot of a rock, may be supposed
to receive more water than that which lies under the rest of the
land;--distance 450 feet. The main drain _E_ requires 2-1/4-inch tiles from
the outlet to the point marked _o_, a distance of 380 feet. This tile
will, in addition to its other work, carry as much water from the spring,
on the line of its fourth lateral, as would fill a 1-1/4-inch pipe.(12)

The length of the main drains above the points indicated, and of all the
laterals, amounts to about 12,250 feet. These all require 1-1/4-inch
tiles.

Allowing about five per cent. for breakage, the order in round numbers,
will be as follows:(13)

3-1/2-inch round tiles 200 feet.

2-1/4-inch round tiles 1,500 feet.

1-1/4-inch round tiles 13,000 feet.

3-1/2-inch ro