This remark does not
apply to large towns, where trees grow with difficulty and are
comparatively few in number, and where they afford a grateful relief
to the eye, shade from the sun, and to a very slight extent temper the
too dry atmosphere, but to suburban and country districts, where it is
the custom to bury houses in masses of foliage--a condition of things
which is deemed the chief attraction, and often a necessary
accompaniment, of country life.
Trees of all kinds exercise a cooling and moistening influence on the
atmosphere and soil in which they grow. The extent of these conditions
depends on the number of trees and whether they stand alone, in belts,
or in forests; on their size, whether tall trees with branchless stems
or thickets of underwood: on their species, whether deciduous or
evergreen; and on the season of the year. The cooling of the air and
soil is due to the evaporation of water by the leaves, which is
chiefly drawn from the subsoil--not the surface--by the roots, and to
the exclusion of the sun's rays from the ground, trees themselves
being little susceptible of receiving and radiating heat.
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