de a grain of sand, or to
bring back to light an enterprising cricket that may have entered on an
exploration. On the whole, solid tiles, with flat-bottomed passages, may
be set down among the inventions of the adversary. They have not the
claims even of the horse-shoe form to respect, because they do not admit
water better than round pipes, and are not united by a sole on which the
ends of the adjoining tiles rest. They combine the faults of all other
forms, with the peculiar virtues of none.

[Illustration: Fig. 33--FLAT-BOTTOMED PIPE-TILE.]

From an English report on the drainage of towns, the following, which
illustrates this point, is taken:

"It was found that a large proportion of sewers were constructed
with flat bottoms, which, when there was a small discharge, spread
the water, increased the friction, retarded the flow, and
accumulated deposit. It was ascertained, that by the substitution
of circular sewers of the same width, with the same inclination and
the same run of water, the amount of deposit was reduced more than
one-half."

THE SIZE OF TILES.

Is a matter of much importance, whether we regard the efficiency and
durability of our work, or economy in completing it. The cost of tiles,
and the freight of them, increase rapidly with their size, and it is,
therefore, well to use the smallest that will effect the object in view.
Tiles should be large enough, as a first proposition, to carry off, in a
reasonable time, all the surplus water that may fall upon the land.
Here, the English rules will not be safe for us; for, although England
has many more rainy days than we have, yet we have, in general, a
greater fall of rain--more inches of water from the clouds in the year.
Instead of their eternal drizzle, we have thunder showers in Summer, and
in Spring and Autumn north-east storms, when the windows of heaven are
opened, and a deluge, except in duration, bursts upon us. Then, at the
North, the Winter snows cover the fields until April, when they suddenly
dissolve, often under heavy showers of rain, and planting time is at
once upon us. It is desirable that all the snow and rain-water should
pass through the soil into the drains, instead of overflowing the
surface, so as to save the elements of fertility with which such water
abounds, and also to prevent the washing of the soil. We require, then,
a greater capacity of drainage, larger tiles, than do the English, for