Drainage of Land. 
275 
ground, though a distinctly different subordinate treatment was 
applied to the two descriptions of lands. 
The mixed open soils were drained by occasional and wide 
parallel drains (from 4 to 8 feet deep), sufficient to discharge 
the rainfall and relieve the pressure of subterranean water passing 
through the soil from the higher grounds to their natural outfalls, 
at a cost varying from 1/. 10s. to 3^. 10s. per acre. The drains 
in this description of soil were reduced to a minimum in number, 
on the principle that any excess of work beyond that sufficient to 
remove excess of wetness would be a waste of outlay ; whereas in 
the gault clay soils, — which were drained uniformly by a parallel 
arrangement of drains 25 and 27 feet apart, 4 feet deep, at a cost 
varying from 5/. 10s. to 6/. 10s. per acre, — the reverse principle 
governed the operations, the number of drains being increased to 
a maximum consistent with economy : the object being two-fold — 
not only to remove excess of wetness, but to promote an uniform 
aeration of the mass of clay above the level of the drains, so as to 
counteract as much as possible its absorbent and retentive nature. 
Tlie total net cost of draining the 800 acres was 3,357Z. 10s. ; 
giving an average cost per acre of 4Z. 4s. ; and a map was 
furnished showing the position of every drain in order that addi- 
tional drains might be put in without derangement of the system 
should any addition be found necessary. 
Description of the tabular Records. — I. Rainfall. — The daily 
quantity of rain which fell during the period over which the 
experiments extend, is shown in columns 1 and 2. 
II. Baeojietric Observations.^ — The height of the barometer 
at the time of recording the rainfall is indicated in column 3. 
III. Discharge of Water from the Drains. — Tlie dis- 
charge from the different outlets is exhibited in columns 7, 9, 11, 
and 16. It will be observed that the discharge from the mixed 
open soils was much more regular than from the clays. The 
quantity of water discharged by the comparatively few drains of 
the freest description of soil, during the period of the experi- 
ments, was 160,920 gallons per acre, out of 227,240 gallons, 
which tlie rain-gauge showed fell upon every acre drained, while 
the quantity discharged from the numerous drains of the clays 
was only 59,936 gallons per acre. 
The steady discharge of more than 1000 gallons per acre per 
diem from the mixed open soils during the winter — when evapo- 
ration is so much less than during the summer — is a fact of con- 
siderable importance when considered in relation to the wide 
extent of similar land requiring drainage. It will be observed, 
loo, that after the Autumn rains had completely replenished the 
T 2 absorbent 
