250 GEOLOGICAL SURVEY 
There are in Barnwell, the lower part of Edgefield, and elsewhere in the State, extensive 
ponds, that from the geological structure of that region, Iam persuaded might be drained at little ex- 
pense, by a simple process that is practised in Kurope with success; [ mean by boring. I have ex- 
plained the manner in which these ponds are formed ; now if the impermeable bottom be perforated 
by boring or by a common well, until a bed of sand or gravel be struck, the water, if conducted mto 
it, will disappear. ‘The orifice must be protected by a covering of pebbles and sand through 
which the water may percolate, otherwise mud, &c., may be carried down and the drain obstructed. 
Series of springs along hill sides are often tapped in this way, and made to sink, instead of overflowing 
the bottom lands. In deep excavations, on rail roads, particularly when they run along the strike of 
the slaty rocks, slides often take place, which are dangerous, and the removal of the fallen earth ex- 
pensive. An ingenious and simple mode of preventing this has been practiced. It consists in bor- 
ing into the side of the cut, giving the hole a sufficient slope to allow the water to run off; iron tubes 
having their sides perforated, are introduced into them, by which means the land is drained, and the 
cause of the sliding removed. 
The waste, by the washing away of the soil from hill-sides, in broken and hilly ground, is a 
serious evil, that requires no ordinary care to prevent. Horizontal ploughing, or ploughing with 
an inclination barely sufficient to carry off the water collected in each furrow, has been proposed 
as a remedy, aud tried, to some extent, in the State; but, however true in principle, the difficulty, 
in practice, is so great, that it has, I believe, been generally abandoned ; or else it has degenerated 
mito mere zigzag lines, which are rather an injury than a benefit. This has been superseded by 
hill-side ditehes—a system more efficient, and far less difficult in practice. The principle consists 
in having the sloping ground traversed by ditches of sufficient capacity and inclination to vent the 
water of the furrows, which are so arranged as to empty themselves into these ditches. 
I saw, in Fairfield and Pendleton, with much pleasure, that improvements of this sort were 
making considerable progress. With regard to grading the ditches, it is plain that the nature of 
the soil must be taken into account, as well as the quantity of water to be carried off. 
In a light soil subject to wash, the inclination must be barely sufficient to carry off the water; 
otherwise a greater evil may be produced than the one to be remedied. 'The capacity of the ditch 
must be increased in order to compensate for the slight inclination. In stiff, tenacious soils the 
slope of the ditches may be greater, and the capacity regulated accordingly. The number of 
ditches required will also be determined by these circumstances, and the height of the hill-side, and 
of course no general rules can be given. 
Operations of this sort are not, like other things, good so far as they go, but may- be absolutely 
an injury, unless properly done. And even when properly constructed, the ditches require constant 
repairs, cleaning out, d&c. in order to their full effect. Where the soil is always kept bare, I know 
of no means of preventing the washing of steep hill-sides, more practicable than this. 
A system of drainage, to be effective, must not only take off the surface water, but the arable 
soil must also be drained to a considerable depth; for, though no water may appear upon the 
surface, the soil may be saturated with moisture, and until this can escape freely, no permament 
improvement of the soil can be effected. 
The effects of drainage on the soil are much more complex than is generally imagined. 'They 
have been studied with great care by Dr. Madden, who, some years since, presented a paper to the 
