, 1877-03-10

that means regained its former level, 30
that the factories can now work without
i7termissiOn.
Another influence, which those who
have been in q forest on a warm day have
observed, is that the temperature is lower
in it than in the open field. This fact re-
quired, however, further research, and
this, in which the best energies of France
have been employed, has always led to
the same result as the immediate obServa-
ton of mankind. NJ. Bequerel has already
adducad numerous examples OF a lower
temperature in forest regions. BY re-
searches in countries near the equator
Bo~ussiogault has found that the mean
temperature in forest regions was as mush
as two degrees lower than in countries
destitute Of forest. NJ. Mathieu> has
made regular observations during q period
of ten years at three different points only 12
miles distant from each other and always
found the mean temperature lower in the
forest than outside Of it, especially in sum-
mer Now, what influence will this lower
temperature in forests have upon the cli-
mate, besides the immediate cooling effect
it exercises 2 In the first place the moisture
in the forest will evaporate with less RAJ
pidity, it being q we'll known fact that
water, other things being equal, evaporates
the quicker, the hotter the atmosphere.
In the second place, it will cause q greater
quantity of rain to fall, rain being produc.
ed by the cooling down of the atmosphere
containing aqueous vapourS to such a
degree that it is no longer capable of sup
porting 80 much water in the vaporltOrm
state, as it would be in a higher state OF
temperature, the surplus falling to the
surface of the earth as rain. AS now,
however, the same air blows over the re-
gions covered with forest as over those
destitute Of that covering, but the lowest
temperature is found in forests, the
air is compelled to give off its moisture
(rain) there This fact is confirmed by
experience. N. Matthew has, at the TIRES
stations, as above mentioned, measured the
rainfall and found that 6olo more rain fell
at the stations surrounded by forest than
at those where Tiers was no forest. FautrAt
has bad two rain gauges at q distance Of
only 200 yards from each other, tho
one above the trees in o Forest
and the other at the same eleva-
ton but above an open or t%reeIeas
space, and during the period Of eight
months there fell three inches more rain at
the former than at the latter (the open
space was in the %forest). BY other inyOs-
tigations the same theory has been con-
frmed, viz that the forests received more
rain than the open land, and at the same
time it was observed that it rained Oftener
in regions rich in forests than in those
where forests are scant, but, on the other
hand, places where forests abound are
much less exposed to real tempestuous
weather than places wanting forest.
Finally, it has been commended that
forests affect the climate by forming q
barrier against the wind, and that they
thus acquire great signi6c ance for vege-
tation as belts sheltering it, is we'll known,
but that they should also in this manner
produce greater rainfall is not yet sufficient
" explained, and there is therefore no reason
why we should enter further upon THE
last question here.