Republican news item. [volume] (Laport, Pa.) 1896-19??, 1899-09-14
TREES AND SUMNER HEAT.
Lower the Temperature and Help to
Purify the Air.

Purify the Air.
DIR. Stephen Smith, in showing that
trees are safeguard against many of
the dangers Of summer heat in cities,
since they tend to lower the tempera.
ture and to purify the air, states that
the Washington elm OF Cambridge,
Mass, a tree of moderate size. was esti-
mated few years since to produce a
crop of 1000, 900 leaves, exposing a
surface of 100000 square feet, or
about five acres of foliage. DR.. Smith
enumerates the causes of the increased
summer temperature Of cities which
SO appreciably raises the mortality of
the lower classes during the hot
months. Among these are the absence
of vegetation, the dr1inage and hence
the dryness of the soil, the covering
OF the earth with stones, bricks and
mortar, the aggregation Of population
to surface area, the massing together
of buildings and the artificial heat
OF workshops and manufactures.
When the summer temperature begins
to rise the solar heat is constantly add
ing to the artificial heat. The tenn
perature of the whole vast mass of
stones, bricks, mortar and asphalt
gradually increases, with no other
mitigation or modification than that
caused by the iaconstant winds and
occasional transforms. DR.. Smith
says the practical remedy for many of
these evils is the planting of large
numbers OF trees in the streets. He
points out that the temperature in
forest, grove, or even small
clump of trees is lower in sum-
mer and higher in winter
than it is in the open. The differ
ence between the temperature of the
air under and among the branches of
single tree, denselv leaved, and the
surrounding air, on hot day, is 20, 80
and 40 degrees, and in the soil there
is difference of from 10 to II de-
grees. The reverse is true i'll winter.
Railroad engineers have to use far less
fuel in passing through forests in
winter than in traversing the same dis
tance in the open country. When the
ground in the fields is frozen two or
three feet deep its temperature in the
forest is found above the freezing
point. Trees, in fact, have normal
temperature, probably approximating
"a degrees Fahrenheit, which they
maintain summer and winter. An
other important effect on temperature
is that caused by the evaporation of
water from the surface of the leaves.
A sunfiower, with surface area of
| 5,616 square inches, throws off at the
iate of twenty to twenty-four ounces
every twelve hours. A vine with
twelve square feet of foliage exhales
at the rate of five or six ounces daily.
1t has been estimated that an acre of
grass emits into the atmosphere g.
quarts of water in twenty-four hours.
1t is this fact which gives significance
to the estimate of the superficial area
of the foliage OF an elm tree. The
advantage of having an automatic evap-
orator under ones window is potent.
DR.. Smith urges the authorities of
cities to take in hand the work of
planting trees freely throughout their
streets. Trees about three inches in
diameter and fourteen feet high can
be planted i'll a city, including trans
! portation from nursery, opening and
7elaying the pavement, providing suit
able iron box and the necessary earth,
At an expense of from s. to 81 each.