have I to effect it?

In draining he has one leading, one master object, we may call it, to
attend to. He has to deepen his soil, that the roots of his crops may
descend further--may draw their food from greater depths, and from a
larger body of earth. The more completely he can effect this, the better
will his work be done.

How deep will his crops send down their roots? In favourable circumstances
his wheat and clover, and even his turnips, will descend to a depth of
three feet. His operations, then, would be in some degree perfect, if he
could so open, and drain, and doctor his land as to enable and induce the
roots of his crops to go down so far as this.

But they will never, or rarely at least, descend lower than the level of
the water in the bottom of his drains. He cannot, therefore, hope to make
his soil available for the growth of his crops to a greater depth than
that to which his drains descend. Three feet then, he will say, appears to
be a reasonable depth for a _perfect_ drain.

Again, drained land must be opened beneath by the subsoil plough, or by
the fork, if the rains, and roots, and air, are to descend, and the full
benefits are to be derived from the drains. With our existing
implements--especially with the fork--the soil may be stirred to a depth
of twenty-six inches. The top of the drain, therefore, should be at least
this depth under the surface; and this, again, brings the whole depth of a
perfect drain to within a few inches of three feet as before.

Then as to the material, it seems advisable to use either stones or tiles,
according as the one or the other is the cheaper, provided always that the
stones are properly broken, and carefully put in. The tide seems now to be
running in favour of smaller tiles than have hitherto been generally used
in Scotland, and even of pipe-tiles of a very small diameter. Our friend
Mr Smith of Deanston has taken out a patent for a pipe-tile, with
projecting fingers at the ends, which dovetail into each other, so as to
unite the tiles together, and at the same time to keep them in their
places. Should these pipes be found generally efficient, the cost of
draining will be considerably diminished, while the small space they
occupy will afford greater facilities for deepening the soil.

But the economical considerations connected with draining, are as
important as the practical methods to be adopted, both to the cultivator
of the soil and to the country at large