, 1888-10-18
TREES SANITARY INFLUENCE.
Their Relation to Dwelling Houses and
to Individual Health.

oDSSldl o0IO vi LIZ OLllOCu Dldlt5 dGIICuI-
tural department on forestry, and many
other contributions, have shown how
rainfall is affected, how the balance of
the atmosphere is disturbed and how
climate changes from the extended and
rapid removal of forests. There is an
other study of trees allied to this which
has reference to their relation to houses
and to individual health.
Both h atmosphere and the soil are
cooled and moistened by the presence of
trees. This results from the drawing up
of the water from the subsoil and from
the exclusion of the SUMS rays. Besides
this, a considerable portion of the rain
fall collects on the leaves and branches.
N. Fantiat has shown s'that the LEAKAGE
of leaf-bearing trees intercepts one-third
and that of pine trees one-half of the
rainfall, which is afterward returned to
the atmosphere by evaporation. On the
other hand, these same leaves and
branches restrain the evaporation of the
water which reaches the ground. This
evaporation is nearly four times less
under a mass of foliage in a forest, and
2 1-3 times under a mass of pines, than
in the OPEN" Then we have stagnation
OF air from that interruption of wind
currents caused by the foliage.
1t is, therefore, not without reason
that the sanitarian studies the trees of
the yard or lawn in their bearing upon
individual health. Persons of s~uscepti-
BILE lungs, or having any tendency to
rheumatism, need to be carefully guarded
against such influences. Where the foil
age is dense about houses, or where the
limbs o~vershadow the piazzas or roof,
they become the storage places for damp,
unwholesome air. The falling leaves
gathering from year to year give n cor
responding dampness to the soil, while at
time of foliage the sunshine is measure
bly, excluded. 1t is pretty evident that
mankind was not intended to be reared
in the woods. The influence of trees in
causing malaria, or in SO i~ntercepting it
as to have it tarry among them, has long
been known. ga dry garden on gravel
of three acres in extent in Surrey, sur
rounded by trees, is generally three or
six degrees colder Than the open COM
mon beyond the trees, and a large pond
in a pine wood twenty miles from Lon
don afforded skating for ninety consecu-
tive days in the winter of 1856, while
during the greater part of the time the
lakes in the London parks were free from
ice."
We know with what interest the lover
of trees watches the growth of those
planted by his own hand, and how many
are apt to be scattered about the new
home mansion. AS years go on, and
their growth and foliage increase, the
owner is 10th to remove them or severely
to shorten their branches. If SO, there
is great danger that the dry soil and once
comfortable home will come to be the
dampest and least desirable spot in the
A raoon+ ao,of,,1 xr,,tor
has given the following sensible direction
as to tree planting as it bears upon the
conditions of health: "a tree should not
stand so near a house that if il were to
fall it would fall upon the house,
or, in other words, the trunk
should be as far from the house
as the height of the tree. Belts of
trees may be planted on the north and
east aspects of houses, but on the east
side the trees should not be SO near
nor SO high as to keep the morning sun
from the bedroom windows in the shorter
days of the year. On the south and west
aspects of houses, isolated trees only
should be permitted, SO that there may
be free access of the sunshine and of the
west winds to the house and grounds.
High wall and palings on these aspects
are also Objectionable, and should be re-
placed by fences, or, better still, by open
palings, especially if the houses are oc-
cupied during the fall of the leaf and in
the winter.
"Trees for planting should be chosen in
the following order: Conifers, birch,
acacia, beech, oak, elm, lime and poplar.
For our American homes we must add
the maple, the ash and the tulip tree, or
American poplar, although the dense
foliage of the maple is sometimes OBJ
jectionable. Pine trees collect the
greatest amount of rainfall and permit
the freest evaporation from the ground,
while their branchless stems offer the
least degree of resistance to the lateral
circulation of the air. Acacias, oaks and
birches are late to burst into leaf, and
therefore allow the ground to be warmed
by the suns raw in the early spring. The
elm, lime and chestnut are the least de-
sirable kind of trees to plant near houses.
They come into leaf early and cast
their leaves early, SO that they exclude
the spring sun and do not afford much
shade in the hot autumn months, when
it is often required. Trees are of value
in indicating choice of residence. Rich
foliage, ferns and moses tell of damp
ness and alluvial deposits. Flowers and
fruit trees point to a dry and sunny site.
Children will be healthiest where most
flowers grow, and old people will live
longest where our common fruits ripen
best. Pines and their companions, the
birches, indicate a sandy OF gravel soil,
elms a rich and somewhat damp
soil, oaks and ashes q heavy clay, pop
lars and willows q low, damp or marshy
soil. Let then our aesthetics be tenn
pered by our desires for health, and
choice and abundance of trees be adapted
to our sanitary needs. Medical Classics.