more, but an open drain, especially if deep, has a constant
tendency to fill up. Besides, the action of frost and water and
vegetation has a continual operation to obstruct open ditches. Rushes
and water-grasses spring up luxuriantly in the wet and slimy bottom, and
often, in a single season, retard the flow of water, so that it will
stand many inches deep where the fall is slight. The slightest accident,
as the treading of cattle, the track of a loaded cart, the burrowing of
animals, dams up the water and lessens the effect of the drain. Hence,
we so often see meadows which have been drained in this way going back,
in a few years, into wild grass and rushes.

3. _They obstruct good husbandry._ In the chapter upon the effects of
drainage on the condition of the soil, we suggest, in detail, the
hindrances which open ditches present to the convenient cultivation of
the land, and, especially, how they obstruct the farmer in his plowing,
his mowing, his raking, and the general laying out of his land for
convenient culture.

4. _They occupy too much land._ If a ditch have an upright bank, it is
so soft that cattle will not step within several feet of it in plowing,
and thus a strip is lost for culture, or must be broken up by hand. If,
indeed, we can get the plow near it, there being no land to rest
against, the last furrow cannot be turned from the ditch, and if it be
turned into it, must be thrown out by hand. If the banks be sloped to
the bottom, and the land be thus laid into beds or ridges, the
appearance of the field may, indeed, be improved, but there is still a
loss of soil; for the soil is all removed from the furrow, which will
always produce rushes and water-grass, and carried to the ridge, where
it doubles the depth of the natural soil. Thus, instead of a field of
uniform condition, as to moisture and temperature and fertility, we have
strips of wet, cold, and poor soil, alternating with dry, warm, and rich
soil, establishing a sort of gridiron system, neither beautiful,
convenient, nor profitable.

5. _The manure washes off and is lost._ The three or four feet of water
which the clouds annually give us in rain and snow, must either go off
by evaporation, or by filtration, or run off upon the surface. Under the
title of Rain and Evaporation, it will be seen that not much more than
half this quantity goes off by evaporation, leaving a vast quantity to
pass off through or upon the soil. If lands are ridged up, t