will enter from above, and give its heat to the
soil, while each rain, as it falls, will also carry its heat with it.
Furthermore, the surface of the ground is sometimes excessively heated by
the summer sun, and the heat thus contained is carried down to the lower
soil by the descending water of rains, which thus cool the surface and
warm the subsoil, both beneficial.

Mr. Josiah Parkes, one of the leading draining engineers of England, has
made some experiments to test the extent to which draining affects the
temperature of the soil. The results of his observations are thus stated
by Gisborne: "Mr. Parkes gives the temperature on a Lancashire flat moss,
but they only commence 7 inches below the surface, and do not extend to
mid-summer. At that period of the year the temperature, at 7 inches, never
exceeded 66 deg., and was generally from 10 deg. to 15 deg. below the temperature of
the air in the shade, at 4 feet above the earth. Mr. Parkes' experiments
were made simultaneously, on a drained, and on an undrained portion of the
moss; and the result was, that, on a mean of 35 observations, the drained
soil at 7 inches in depth was 10 deg. warmer than the undrained, at the same
depth. The undrained soil never exceeded 47 deg., whereas, after a thunder
storm, the drained reached 66 deg. at 7 inches, and 48 deg. at 31 inches. Such
were the effects, at an early period of the year, on a black bog. They
suggest some idea of what they were, when, in July or August, thunder rain
at 60 deg. or 70 deg. falls on a surface heated to 130 deg., and carries down with it,
into the greedy fissures of the earth, its augmented temperature. These
advantages, porous soils possess by nature, and retentive ones only
acquire them by drainage."

Drained land, being more open to atmospheric circulation, and having lost
the water which prevented the temperature of its lower portions from being
so readily affected by the temperature of the air as it is when dry, will
freeze to a greater depth in winter and thaw out earlier in the spring.
The deep freezing has the effect to greatly pulverize the lower soil, thus
better fitting it for the support of vegetation; and the earlier thawing
makes it earlier ready for spring work.

*Drought.*--At first thought, it is not unnatural to suppose that draining
will increase the ill effect of too dry seasons, by removing water which
might keep the soil moist. Experience has proven, however, that the result
is ex