156 
On the Quantity of Rain- Water, 
drainage now pursued in Kent has doubtless been encouraged by 
the cheapness, lightness, and approved action of the pipe-tiles, 
combined with the more moderate cost of the earth-work incident 
to their small dimensions, and to the facility of laying them. The 
aggregate cheapness of the work has set the mind of the farmer 
free to contemplate more exclusively and attentively the perfection 
of the end in view ; and it is well worthy of remark, that experi- 
ment and experience have rapidly induced the adoption of a system 
of parallel drains considerfibly deeper, and less frequent, than 
those commonly advocated by professed drainers, or in general 
use. I gave several instances of this practice in Kent in the 
report of last year, already alluded to, and it is rapidly extending. 
Mr. Hammond stated to you (Journal, vol. iv. p. 47), that he 
drained " stiff clays, 2 feet deep, and 24 feet between the drains, 
at 3Z. 4s. 3c?. per acre," and " porous soils, 3 feet deep 33 J feet 
asunder, at 2Z. 55. 2d. per acre." I now find him continuing 
his drainage at 4 feet deep, wherever he can obtain the outfall, 
from a conviction, founded on the experience of a cautious pro- 
gressive practice as to depth and distance, that depth consists 
with economy of outlay as well as with superior effect. He has 
found 4 feet drains to be efficient, at 50 feet asunder, in soils of 
varied texture — not uniform clays — and executes them at a cost of 
about 21. 5s. per acre, being 18s. 4d. for 871 pipes, and II. 6s. 6d. 
for 53 rods of digging. Communications have been recently 
made to me by several respectable Kentish farmers, of the satis- 
factory performance of drains deeply laid in the Weald clays, at 
distances ranging from 30 to 40 feet, but I have not had the 
opportunity of personally inspecting these drainages. 
The following little table shows the actual and respective cost of 
the above three cases of under-draining, calculated on the effects 
really produced, i. e. on the masses of earth effectively relieved of 
their surplus water at an equal expense. I conceive this to be 
the true expression of the work done, as a mere statement of the 
cost of drainage per acre of surface conveys but an imperfect, 
indeed a very erroneous, idea of the substantive and useful expen- 
diture on any particular system. This will be apparent on refer- 
ence to the two last columns of the table, which give the cost in 
cubic yards and square yards of soil drained for one penny, at 
the above mentioned prices, depths, and distances : — 
Depth of the 
Drains in Feet. 
Distance between 
the Drains in 
Feet. 
Mass of Soil 
drained per Acre, 
in Cubic Yards. 
Mass of Soil 
drained for Id., in 
Cubic Yards. 
Surface of Soil 
drained fur \d., 
in Square Yards. 
2 
2t 
3226^ 
41 
6-27 
3 
4840 
8-93 
8-93 
4 
60 
6153 
12- 00 
8-96 
