THE PHILOSOPHY OF FARMING. 583 
when dug to the greatest depth All attempts 
to dry such soils by drains must therefore fail. 
The only plan is to dig open channels through 
the soil, a few inches deep into the clay, that the 
water may flow away from the surface as readily 
as possible after every fall of rain, and not 
stagnate in the furrows. Such open channels 
ought to take the most direct course for the dis- 
charge of the water; and in meadow grounds 
should be annually freed from the water plants, 
which may have grown within them. 
When water swamps the surface of the ground 
solely from filtering down from higher grounds 
into a kind of natural basin of impervious rocks — 
a single drain tapping the inlet is commonly 
sufficient to dry the whole. In intermediate soils 
such as are formed chiefly by alluvial deposits on 
holm lands, and flats on the banks of rivers, which 
flow through clayey districts, where the subsoil 
consists of layers of gravel and fine sand, inter- 
mingled with layers of impervious clay, it not 
unfrequently happens, that after all attempts to 
dry the surface by ordinary methods have failed— 
one or two drains cut very deep, and penetrating 
the stratum in which the water lodges, suffice to 
dry whole fields of many acres. Successful 
