DRAINAGE OF SOILS. 
324 
he found under the head of Rumbling Drains. Much land of the above 
description, in various districts of this country, may be completely 
drained in the same manner, at a very moderate expense, by a proper 
attention being paid to the situation of the ground and cause of the 
wetness. Such land remains so long wet in spring before it can he 
sown, that the crop is either obliged to he cut green, or, in some 
instances, is lost altogether. 
DRAINAGE OF CLAY-SOIL INJURED BY SURFACE WATER. 
Owing to a considerable portion of the ploughable land in this 
country being injured by surface water, or water lodged between the 
soil and sub-soil, systems as various as the effects they produce have 
of late been applied to drain such, and it therefore becomes a matter 
of the greatest importance that some definite rule be laid down, 
whereby a complete and permanent drainage may be effected in such 
land, and which at the same time, will be attended with the least 
expense. 
Tenacious soils are much more expensive to drain than any other, 
as the drains must be more numerous, in consequence of having to 
be laid out in such a manner as to collect all the water from the 
surface, which, from the imperfect viability of the clay, must, in 
many cases, discharge itself into them from above; and where there 
is any irregularity on the ground, the water will remain standing 
in the hollows if a drain is not carried through each of them. 
Drains for removing surface water from such land, when it lies flat, 
should therefore go through the hollowest parts of the field, without 
any respect to straightness or regularity, and at such a distance from 
each other as will keep the surface of the land dry. When the soil 
and sub-soil are composed of strong clay, twenty feet between the 
drains may be fixed on as a general rule at which they will act; but 
when the clav is mixed with thin veins of very fine sand, which is 
very often the case, thirty feet will answer completely. When the 
ground, however, has the least declivity, the drains should always be 
directed obliquely across the slope, or as directly across it as the 
nature of the surface and outlet will allow: the distance of one drain 
from another,.in this case, depends on the declivity, the preparation 
of sandy substance mixed with the clay, and the depth of the drain. 
Where the soil is very tenacious, and the declivity considerable, the 
drains will not act more than twenty or thirty feet; but where it is 
mixed with thin strata of fine sand, although the sand is hardly 
perceivable, the same depth of drain will act several times that dis¬ 
tance. The necessary dimensions of drains for removing surface water 
is found, from experience, to be from two and a half, to three feet 
