n each farm, to make the matter so safe, that the owner need not have
an anxious thought, as he wakes in a howling Winter night, lest his
drains should be freezing.

Finally, in view of the various considerations that have been,
suggested, as well as of the almost uniform authority of the ablest
writers and practical men, it is safe to conclude, that, in general, in
this country, wherever sufficient outfall can be had, _four feet above
the top of the tiles should be the minimum depth of drains_.

CHAPTER VIII.

ARRANGEMENT OF DRAINS.

Necessity of System.--What Fall is Necessary.--American
Examples.--Outlets.--Wells and Relief-Pipes.--Peep holes.--How to
secure Outlets.--Gate to Exclude Back-Water.--Gratings and Screens
to keep out Frogs, Snakes, Moles, &c.--Mains, Submains, and Minors,
how placed.--Capacity of Pipes.--Mains of Two Tiles.--Junction of
Drains.--Effect of Curves and Angles on Currents.--Branch
Pipes.--Draining into Wells or Swallow Holes.--Letter from Mr.
Denton.

As every act is, or should be, a part of a great plan of life, so every
stake that is set, and every line laid in the field, should have
relation not only to general principles, but also to some comprehensive
plan of operations.

Assuming, then, that the principles advocated in this treatise are
adopted as to the details, that the depth preferred is not less than
four feet--that the direction preferred is up and down the slope--that
the distance apart may range from fifteen to sixty feet, and more in
some cases, according to the depth of drains and the nature of the
soil--that no tiles smaller than one and a half inch bore will be used,
and none less than two inches except for the first one hundred yards,
there still remains the application of all these principles to the
particular work in hand. With the hope of assisting the deliberations of
the farmer on this point, some additional suggestions will be made under
appropriate heads.

ARRANGEMENT MUST HAVE REFERENCE TO SYSTEM.

The absolute necessity of some regularity of plan in our work, must be
manifest. Without system, we can never, in the outset, estimate the
cost of our operation; we can never proportion our tiles to the quantity
of water that will pass through them; we can never find the drains
afterwards, or form a correct opinion of the cause of any failure that
may await us.

We prefer, in general, where practicable, parallel