in June. In Midsummer, however, under our burning sun,
it had, by evaporation, been so much dried as to produce the effect
described.

In England, we learn, that these cracks extend to the depth of four
feet or more. Mr. Hewitt Davis stated in a public discussion, with
reference to draining strong soils, that, "he gave four feet as the
minimum depth of the drains in these soils, because he had always
found that the cracks and fissures formed by the drought and
changes of temperature, on the strongest clay, and which made these
soils permeable, extended below this depth, and the water from the
surface might be made to reach the drains at this distance."

In clay that has never been dried, as for instance, that found under wet
meadows from which the water has but recently been drawn, we should not,
of course, expect to find these cracks. Accordingly, we find sometimes
in clay pits, excavated below the permanent water-line, and in wells,
that the clay is in a compact mass, and tears apart without exhibiting
anything like these divisions.

We should not expect that, on such a clay, the full effect of drainage
would be at once apparent. The water falling on the surface would very
slowly find its way downward, at first. But after the heat of Summer,
aided by the drains underneath, had contracted and cracked the soil,
passages for the water would soon be found, and, after a few years, the
whole mass, to the depth of the drains, would become open and permeable.
As an old English farmer said of his drains, "They do better year by
year; the water gets a habit of coming to them." Although this be not
philosophical language, yet the fact is correctly stated. Water tends
towards the lowest openings. A deep well often diverts the underground
stream from a shallower well, and lays it dry. A single railroad cut
sometimes draws off the supply of water from a whole neighborhood.
Passages thus formed are enlarged by the pressure of the water, and new
ones are opened by the causes already suggested, till the drainage
becomes perfect for all practical purposes. So much is this cracking
process relied on to facilitate drainage, that skillful drainers
frequently leave their ditches partly open, after laying the tiles, that
the heat may produce the more effect during the first season.

As to the depth of drains in stiff clays, enough has already been said,
under the appropriate title. In England, the