, and the Board of
Agriculture appointed a Mr. Johnstone to study the process, and write a
treatise on the subject.

Catch-water drains, made so as to intercept a flow of surface water, have
been in use from immemorial time, and are described by the earliest
writers. Before the advent of the Draining Tile, covered drains were
furnished with stones, boards, brush, weeds, and various other rubbish,
and their good effect, very properly, claimed the attention of all
improvers of wet land. When the tile first made its appearance in general
practice, it was of what is called the "horse-shoe" form, and,--imperfect
though it was,--it was better than anything that had preceded it, and was
received with high approval, wherever it became known. The general use of
all these materials for making drains was confined to a system of
_partial_ drainage, until the publication of a pamphlet, in 1833, by Mr.
Smith, of Deanston, who advocated the drainage of the whole field, without
reference to springs. From this plan, but with important modifications in
matters of detail, the modern system of tile draining has grown. Many able
men have aided its progress, and have helped to disseminate a knowledge of
its processes and its effects, yet there are few books on draining, even
the most modern ones, which do not devote much attention to Elkington's
discovery; to the various sorts of stone and brush drains; and to the
manufacture and use of horse-shoe tile;--not treating them as matters of
antiquarian interest, but repeating the instructions for their
application, and allowing the reasoning on which their early use was
based, to influence, often to a damaging extent, their general
consideration of the modern practice of tile draining.

These processes are all of occasional use, even at this day, but they are
based on no fixed rules, and are so much a matter of traditional
knowledge, with all farmers, that instruction concerning them is not
needed. The kind of draining which is now under consideration, has for its
object the complete removal of all of the surplus water that reaches the
soil, from whatever source, and the assimilation of all wet soils to a
somewhat uniform condition, as to the ease with which water passes through
them.

There are instances, as has been shown, where a large spring, overflowing
a considerable area, or supplying the water of an annoying brook, ought to
be directly connected with the under-ground drainage, and its f