ell as Receive
it.--Defence against Water from Higher Land.--Open
Ditches.--Headers.--Silt-basins.

DISTANCE OF DRAINS.--Depends on Soil, Depth, Climate, Prices,
System.--Conclusions as to Distance.

DEPTH OF DRAINS.--Greatly Increases Cost.--Shallow Drains first
tried in England.--10,000 Miles of Shallow Drains laid in Scotland
by way of Education.--Drains must be below Subsoil plow, and
Frost.--Effect of Frost on Tiles and Aqueducts.

DIRECTION OF DRAINS.

Whether drains should run up and down the slope of the hill, or directly
across it, or in a diagonal line as a compromise between the first two,
are questions which beginners in the art and mystery of drainage usually
discuss with great zeal. It seems so plain to one man, at the first
glance, that, in order to catch the water that is running down under the
soil upon the subsoil, from the top of the hill to the bottom, you must
cut a ditch across the current, that he sees no occasion to examine the
question farther. Another, whose idea is, to catch the water in his
drain before it rises to the surface, as it is passing up from below or
running along on the subsoil, and keep it from rising higher than the
bottom of his ditch, thinks it quite as obvious that the drains should
run up and down the slope, that the water, once entering, may remain in
the drain, going directly down hill to the outlet. A third hits on the
Keythorpe system, and regarding the water as flowing down the slope,
under the soil, in certain natural channels in the subsoil, fancies they
may best be cut off by drains, in the nature of mains, running
diagonally across the slope.

These different ideas of men, if examined, will be found to result
mainly from their different notions of the underground circulation of
water. In considering the Theory of Moisture, an attempt was made to
suggest the different causes of the wetness of land.

To drain land effectually, we must have a correct idea of the sources of
the water that makes the particular field too wet; whether it falls from
the clouds directly upon it; or whether it falls on land situated above
it and sloping towards it, so that the water runs down, as upon a roof,
from other fields or slopes to our own; or whether it gushes up in
springs which find vent in particular spots, and so is diffused through
the soil.

If we have only to take care of the water that falls on our own field,
from the clouds,