120 
On the Influence of Water 
field of investigation ; but, on the contrary, there is reason to 
anticipate that his labours would be made in a land of promise, 
and that they would be abundantly repaid. 
Previously to detailing my own and other very limited experi- 
ments on the temperature of soils, it may be well to consider 
some of the operations of the husbandman, their intent, and the 
manner in which the heat and moisture of a soil may be affected 
by them. The two principal agricultural processes, upon which, 
perhaps, the fertility of land depends as much as on the 
artificial aids now so scientifically and beneficially applied to 
it, are drainage and pulverization.* These mechanical opera- 
tions are practically known to be indispensable to the full deve- 
lopment of the natural powers of soils, as well as to the profit- 
able employment of the numerous and costly stimulants latterly 
introduced into agriculture ; and it is my present object to show 
that the tempeiature of soil is materially influenced by the per- 
fection of these processes ; and that each particular soil is bene- 
fited by them, according to the degree in which it may require to 
be artificially drained or worked. You have forcibly remarked 
that " all who are acquainted with improved husbandry are now 
agreed that, on wet land, thorough-draining is to a farm what a 
foundation is to a house."'f- Water, indeed, forms an essential 
element in soil, but there may be as much difference, in re- 
spect of fertility, between a tcet soil and a moist one — though they 
be identical in other respects — as between a swamp and a garden. 
By drainage and pulverization the proper degree of humidity is 
to be attained in most soils ; for, though it is wisely ordained that 
we cannot control the precipitation of rain, we do possess the 
power of regulating, within certain limits, the quantity of moisture 
to be retained by the earth, and of adjusting it, as it were, to 
the quality of the soil, and to the requirements of vegetation. 
Physical Action of Water. 
The consideration of the well-known effect of drainage on soils 
surcharged with water, naturally leads to an examination of the; 
causes of the change produced in them by so simple an operation. 
A soil perfectly dry, or one perfectly wet, i. e. constantly drenched 
with water, would be nearly alike sterile ; and we may conceive 
that some certain proportions may exist between the amounts of 
♦ The term drainage is here used in an extensive sense, not confining it 
to the construction of aitificial conduits for water, nor to its application on 
those soils only wliich are reputed as wel. The mere acts of digging, 
ploughing, and working soils rei)ut('d as dry, do, in reality, effect drainage 
by opening channels for the descent of water from t he su]>erficial to the 
lower strata. 
■|- Journal, vol. iii. p. 170. 
