Oil Drainiiif/. 421 
• 
thus approximate nearer the true principle of draining clay- 
soils ; for such persons, acting under the erroneous impression 
that the water enters the conduit through the fdUng-in or me- 
dium over it, and not, as is the case, at the bottom, will lay the 
materials as near the surface as the necessary acts of cultivation 
will allow, and tile-drains being less liable to injury when laid 
near the surface than wood and peat, accounts for the latter 
acting better, as long as the conduit is not impeded, than the 
shallow drains formed with tiles, and thus the effect which arises 
from the increased depth is attributed to the materials of which 
the drains are formed. I consider I have already stated suffi- 
cient to prove that the obstruction to the entry of the water into 
the conduit of the drain does not exist near it, where the drains 
are laid deep, but at the surface ; and, if so, there cannot be a 
question but that the material which makes the most regular and 
permanent conduit must be the best. Where parties (tenants) 
have plenty of wood growing upon their farms (willows, black- 
thorn, or even white), if they have not security for the outlay of 
capital necessary to effect a thorough and permanent drainage, 
for temporary purposes the use of peat, wood, or any other mate- 
rial or mode which is done at little expense, may be advisable ; 
but if such materials are used, it will always be to the advantage 
of the occupier to have the drains laid deep. 
5th. Fillinr/-iii, whetlier with tenacious or porous earth. 
In no part of draining is there greater ignorance shown than 
in filling-in the drain after the conduit is formed upon tenacious 
clay soils. The modes adopted are very numerous, many of 
which I am unacquainted with, but the system generally adopted 
is to fdl the drain immediately over the conduit with sod or turf, 
refuse wood, straw, or the surface-soil. The use of a good tough 
sod 1 inch thick, laid immediately over the tile to prevent the 
entry into the conduit of sand or other light substances with 
which the drain above the same is filled, is in many instances 
beneficial ; but, with this exception, I am most decidedly opposed 
to putting any of the materials named in preference to the clay 
immediately above the conduit.* I have shown that attention to 
levelling the surface and deep draining is the most effectual in 
laying land dry, and not the material used to Jill- in above the con- 
duit; but if the difficulty did lie immediately over the conduit, 
* Stones are rarely to be obtained in the clay-land districts of the south and 
east of England. 1 have for an experiment in a few yards of drain put 2 
inches of stones, and beaten them down with a rammer, which I consider 
would be a good substitute where soles are not to be readily obtained ; and 
I hesitate not in saying that if 2 inches of stones were laid in the bottom of a 
drain on a tenacious clay subsoil, then a sole and tile, and upon the tiles 2 
inches of stones, a greater quantity of water would pass through the lower 
lhan through the upper bed of stones. 
