ns
more simple than the span level. We give the cut and explanation.

"I first ascertain what amount of fall I can obtain, from the head
of every drain to my outfall. Suppose the length of the drain to be
96 yards, and I find I have a fall of two feet, that gives me a
fall of a quarter of an inch in every yard. I take a common
bricklayer's level 12 feet long, to the bottom of which I attach,
with screws, a piece of wood the whole length, _one inch wider_ at
one end than at the other, thereby throwing the level one inch out
of the true horizontal line. When the drain has got to its proper
depth at the outfall, I apply the broadest end of the level to the
mouth; and when the plumb-bob indicates the level to be correct,
the one-inch fall has been gained in the four yards, and so on. I
keep testing the drain as it is dug, quite up to the head, when an
unbroken, even, and continuous fall of two feet in the whole 96
yards has been obtained."

[Illustration: Fig. 60.--CHALLONER'S LEVEL.]

SPADES AND SHOVELS.

[Illustration: Fig. 61, 62, 63.--DRAIN SPADES.]

No peculiar tool is essential in opening that part of the drain which is
more than a foot in width. Shovels and spades, of the forms usually
found upon well-furnished farms, and adapted to its soil, will be found
sufficient. A Boston agricultural house, a year or two since, sent out
an order to London for a complete set of draining tools. In due season,
they received, in compliance with their order, three spades of different
width, like those represented in the cut.

These are understood to be the tools in common use in England and
Scotland, for sod-draining, and for any other drains, indeed, except
tiles. The widest is 12 inches wide, and is used to remove the first
spit, of about one foot depth. The second is 12 inches wide at top, and
8 at the point, and the third, eight at top, and four at the point. The
narrowest spade is usually made with a spur in front, or what the Irish
call a _treader_, on which to place the foot in driving it into the
earth.

[Illustration: Fig. 64. SPADE WITH SPUR.]

For wedge drains, these spades are made narrower than those above
represented, the finishing spade being but two and a half inches wide at
the point. It will be recollected that this kind of drainage is only
adapted to clay land. The shovels and spades which have been heretofore
in most common use in N