by the character of the home which Providence has appointed, and we have
fashioned, for our material habitation. [Footnote:Gods Almagt wenkte van
den troon, En schiep elk volk een land ter woon: Hier vestte Zij een
grondgebied, Dat Zij ona zelven scheppon llet.] It is still too early to
attempt scientific method in discussing this problem, nor is our present
store of the necessary facts by any means complete enough to warrant me
in promising any approach to fulness of statement respecting them.
Systematic observation in relation to this subject has hardly yet begun,
and the scattered data which have chanced to be recorded have never been
collected. It has now no place in the general scheme of physical
science, and is matter of suggestion and speculation only, not of
established and positive conclusion. At present, then, all that I can
hope is to excite an interest in a topic of much economical importance,
by pointing out the directions and illustrating the modes in which human
action has been, or may be, most injurious or most beneficial in its
influence upon the physical conditions of the earth we inhabit We cannot
always distinguish between the results of man's action and the effects
of purely geological or cosmical causes. The destruction of the forests,
the drainage of lakes and marshes, and the operations of rural husbandry
and industrial art have unquestionably tended to produce great changes
in the hygrometric, thermometric, electric, and chemical condition of
the atmosphere, though we are not yet able to measure the force of the
different elements of disturbance, or to say how far they have been
neutralised by each other, or by still obscurer influences; and it is
equally certain that the myriad forms of animal and vegetable life,
which covered the earth when man first entered upon the theatre of a
nature whose harmonies he was destined to derange, have been, through
his interference, greatly changed in numerical proportion, sometimes
much modified in form and product, and sometimes entirely
extirpated. [Footnote: Man has not only subverted the natural numerical