He was called upon to examine a field in which drains
three and a half feet deep had been sunk without effect
on the water below, and it was therefore supposed that
drains, two feet deep, to carry off the surface moisture,
would equally answer the purpose. To ascertain if there
was a porous stratum below the deeper drain, he made a
hole in the putty-like clay, between four and five feet
deep, and it soon filled with water. He had therefore
found the level of a porous vein ; he then cut a drain fully
five feet deep, laid pipes below, and puddled clay over
them to withm thirty inches of the surface, and on this
level and over this puddled water-tight clay he laid a
second course of pipes, so that he had two drains at dif-
ferent levels in the same trench, of which the lower was
so protected by the close clay overhead, that none of the
top water could intermingle with that at the bottom.
