The watchman and southron. [volume] (Sumter, S.C.) 1881-1930, 1909-08-18

II
causing motion in the water drawing
1, up into the mass OF soil; that Is to
say, into the free spaces among the
soil rerticles. An easy experiment to
make illustration of the foregoing is
to take a hard cubical loaf Of sugar
and merely touch the corner OF the
cube to the surface of your tea. and
observe how rapidly the tea rises into
the sugar.
These very small free spaces exist
| Ing in a mas Of soil are what We
call pores. The voids In a mass OF
broken stone or pebbles or coarse
slnd. differ from pores only in mag
nitude. That property of porous mass
es by virtue Of which they can ohsorb
,'uids even against the force Of grav-
ity We call capiilarity, and is no other
than the surface tension above al
,uded to. II Is the same force that
causes the oil to rise in the lamp
wick. or the sap to rise in trees.
The more compact clay soil be-
comes, up to certain extent ~ 'w,st,
the greater us Its capillarity. II the
soil In the seive Is loose the water
will rise into 1t very slowly; and 1t
we do not limit the soil to depth,
The water may not appear upon the
surface even after long contact with
the bottom of the soil. as the wa'"i
may be taken up and carried off b.
the atmosphere. which circulates
through the soil as fas, as 1t is suck
Ell up from below. ,On the otter
hand. IL you could At into the sieve
lump Of dry clay soil just as 1t comes
frop some hard undained field. 1t
would draw up the water more rapid
ly. and the water would rise much
higher into the soil; probably many
feet II the soil is Of only moderate
depth. the water would soon show it.
self on top OF the soil by dampness of
the surface, and the mass would ap-
pear quite saturated with water.
Even IL the soil extends In height
four or more feet above the surface
of the water. but for evaporation the
surface would appear always damp.
This four or more feet of clay soil
then is in exactly the same condition
cf the same class Of soil out Of yc.r
undrained field. retention by nature,
and always either water logged or
baked hard by the sun. Instead of
the water running out Of it the soil is
sucking the water up into itself al
most to the point Of saturation. and
giving it up only to evaporation at
the surface.
How can we drain a soil If the wa
ter will not run out of It? II the wa
ter will not run out of this mass Of
soil in our experiment how can 1t
ever run out of the field into the
drains under the field?
/ was once approached by farmer
of lifelong experience in his voca-
tion upon the subject Of draining his
clay lands. He was afraid that water
would not run out clay land, and
did not believe that such land could
be drained. have endeavored in the
foregoing to describe the mechanical
condition of clay soils in their natur-
al state. in order further on to meet
the argument of this class of objec-
tors. This gentleman saw the sit
uation just as 1 have seen and at
tempted to describe 1t, and had
drawn the same conclusions from the
facts given above and already OBJ
served by him that I should have
deduced for myself had not had the
opportunity of seeing further.
Through free soils the pe-colat;on
of water goes on as evenly as through
seive. but of course thes, soils.
heh underlaid by q compa -atiyely
irapervious material may become
filled with water to the surface. II IL
easy to understand how such soils
may be- relieved of their successive
wetness by a few drains, at wide in
tervals, through them. The water de-
scending entirely fills the mass Of soil
below the drains, and In rising to the
levels Of the drains begins to flow on
through them just as 1t would over a
dam. In the drainage OF these soils
the mechanical operation Of the
drains Is all there is to it, But the
drainage Of clay soils is more COM
plex. 1t is true that, when we have
constructed the drains we have done
our part but the mere presence of
underground conduits though they
perform their duties afficiaptIv uybara