The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1856-1888, 1878-04-06
More About Forests.

AT a recent scientific Congress held in Chicago, a
paper was read by DIR. George L. Andrew, Of
Laporte, Ind, on The Sanitary Value Of Forests
A considerable portion Of the essay was devoted TO
tracing the decay Of prosperous districts simultane-
ously with the destruction of forests. The question
was an important one whether America would ulti-
mately suffer the fate which had overtaken large
sections of the Eastern Hemisphere. lie commended
the action of Congress in appointing a Commission
which had for its object the promotion Of tree-plant-
ing and the conserving of the forests. He went on
to show that animal life and vegetation we're COM
Elementary forces, the oxygen Of the trees neutraliz-
ing the carbolic acid gas emanating from animals
which distilled moisture from the atmosphere. The
paper sought to demonstrate that they Influenced in
an important degree the rain-supply, and went on
to show the beneficial effects of forests in a sanitary
point Of view, pointing out also the drawbacks to
their usefulness in particular sections.
The sanitary value Of forests was thus summed
up by DIR. Andrews:
l.. Forests increase the amount Of condemnation
over their own areas; but by reason of the amount
intercepted by their stems and leaves, the annual
rainfall at the earth's surface is not, perhaps, mate
rally affected by their presence or absence in
regions we'll covered with other vegetation and well
cultivated.
2. By means of their interlaced roots, MOSES.
lichens, and humus, forests check the efiux Of
superfuous rainfall, thus regulating the water-sup-
ply in streams and springs, and decreasing the pro-
portion of the annual precipitation that is borne TO
the sea by the natural drainage of the country.
3. Forests diminish the evaporation from the
earth's surface, but this hygrometric deficiency is
more than compensated by the increased evapora-
ton from their leaves. Forests may thus become
beneficial or otherwise, according to circumstances.
The change which tree-planting has produced upon
our Western plains Is thus far an unmixed good
but, by increasing the humidity of the climate of
certain health resorts, as Of Denver, valued mainly
for its dryness, extensive tree-planting is not un-
accompanied with evil.
4. Trees modify mperatuTe-wooded countries
being warmer in winter and cooler in summer. This
they do by radiation; but by means Of their slow
conducting power the times Of their daily maximum
and minimum do not occur until some hours after
the same phases in the temperature Of the air, thus
distributing the heat Of the day more equally over
the twenty-four hours. The special significance Of
this effect lies in the fact that, as related to human
health, the daily range Of the thermometer is Of
more Importance than the mean temperature Of
whole seasons.
5. Trees radiate and evaporate to a stratum Of
air equaling in thickness their height, whilst the
radiation and evaporation from grasses, plants, and
shrubs is confined 10 a stratum limited to the COM
parative lesser planes which they occupy.
6. From the preceding it may be fairly inferred
that forests modify climate to the extent Of iDduen-
cling the amount and character Of the diseases in
their vicinity. lin this inquiry residence an forests
is not considered, universal experience having
shown those situations which are permanently
shaded to be insalubrious.)
Z. Forests and tree-belts are Of undoubted value
in preventing the dissemination Of malaria.
s. Trees are Of positive sanitary value in Afford
ing shelter from the excessive heat Of the sun, from
the violence of winds, and in promoting esthetic
culture.
9. The importance Of deyoting to forests all re-
gions unfit for profitable cultivation, and Of protect
ing them by an enlightened public sentiment, as
well as by legal enactment, may be fairly assumed
as a sanitary as well as an economical necessity.
10. And finally, as particularly relating TO the
city whose hospitality we are now enjoying, the i'm
portance of abundant and extensive tree-planting,
especially on its western and southwestern expo
sures, which was so ably urged by our worthy
President in 1869, is such as should command the
immediate and earnest attention Of every one in
terested in its welfare.
The secretary supplemented the reading Of the
paper by presenting a contribution from Professor
Brewer, Of the Agricultural School Of Yale College,
on the value Of forests as q source Of fuel and
various crude uses in relation to sanitary matters
and public economy, and particularly on the use of
belts of trees on agricultural grounds.