Weekly expositor. (Brockway Centre, Mich.) 1882-1894, 1888-06-07

THE DURABILITY OF TIMBER.

Der.
The United States Department of
Ayr culture, Forestry ID vision. has is
sued II circular to wood consumers con-
corning the desirability of increasing
the durability of timber, from which we
make some extracts.
Decay of wood is due to fermentation
Of the sap. induced probably by the
growth of either bacteria or fungi.
These organisms need for their devel-
opement warmth and moisture, besides
the heterogeneous substances and salts
contained in solution in the sep. To
prevent this growth of these ferments,
therefore. the sap in the wood must be
dissolved. leached or dried out. and
mo sture be prevented from entering
again.
Timber placed entirely under water
or deep in soil, as drain pipes, will
practically not decay nor is it liable to
rot when kept absolutely dry away
from the influence of humid atmosphere.
Wood generally decays in proportion to
The warmth of the temperature. Hence
on northern exposures, in cool valleys.
on high elevations, IN northern coun-
tries. the duration of wood is longer
than when placed under opposite in-
huenccs.
Ii wood is used in contact with the
ground. decay proceeds more rapidly,
1he looser, mOlster and warmer the
soil, and especially the greater the La
bihty OF change from dry to wet. There
lore timber will last longer in heavy,
dlN ays IN list clay than IN loose al ornate
moist and dry sand gravel, or in warm,
comparatively dry lime soils. Rooms
without venGlation induce decay, pro-
uucmg the dry rot VIII ch first appears
IA white patches. changing into brown
" gray. Ventilation and drying out
aud isolation from moisture Will cure
this detect
Sound, mature trees yield more dur
anie timber than either young or very
old trees. Maturity IS the time when
trees have ceased 10 grow vigorously,
winch is indicated by II ilattenng of the
crown. dying out OF branches in the
crown, aud by the change of the color
If The bark. Maturity may be reached
according to circumstances by the same
species when the diameter is one and Il
naif inches, or when it 5 as many feet.
A small tree on arid soil, or over-topped
y others from its birth, may be rs old
tni older than u tree OF greater dlmen-
-luus growing undOr more favorable
conditions. OF TWO pieces of the same
kind, the heavier is more durable, al
though absolute weight of two different
Kind Of timber does not determine their
relative durability.
Heart wood, rs rule can resist de-
tcrioraIion longer than sap wood. be-
cause it contains less sap. When the
sap wood is well seasoned and heavier
however, this difference disappears.
fac site has an influence on durability
SO far is 1t influences the formation
Of heavy wood.
Quickly grown hard wood with wide
annual rings. and slowly-grown con-
tiers with narrow yet not too narrow
rings. and tapped pines. yield on the
| tapped side as rule. the most dura-
bic wood. other cond lious being equal.
| Coniferous wood from comparatively
poor soils high altitude and dense Tor
est. hard woods from, rich, deep, warm
soils and isolated positions, are most
durable. The resinous substances n
! confers offer an element of protection
against decay.
With proper after-treatment of the
wood time of telling seems not TO af-
feet It's durability Early Winter fell.
ing should have the preference. because
less .ermenlable sap IS then in the
trees, and the timber will season with
less care. more slowly and more even
| w and before the weather 10 warm
enough for fermention to set la.
If the wood is cut "in the sap it is
more liable to fermentation and to the
attacks of insects, and more care Is
necessary in season .ng. The rapid sea
soning. due to the warm. dry atmos.
phere, produces an outer seasoned coat
| which envelopes an unseasoned inter
| Tor liable to decay. When cut IN the
leaf it is advantageous to let the trees
lie full length until the leaves are
thoroughly withered. say two or three
weeks. before cutting TO size. With
conifers THIS is good at any season.
Where possible all Winter folled trees
should be left lying to leaf out IN
Spring. bv which most Of the sap il
worked out and ovaporated.
As TO the treatment of timber after
telling, always remove the bark to aid
n seasoning. Never remove bark from
q standing tree, aud never allow the log
to lie directly on the moist soil. Il
Winter-feled shape the timber TO size
within two weeks after telling and leave
it placed OH blocks in the forest, or il
shaped at home. place in dry, airy,
not windy position, away from sun ant
rain.
II dried too rapidly. wood warps and
splits, the cracks collect water, and the
timber is then easily attacked and de.
slroyed by rot. With large logs.
checking may be prevented by coating
the ends with brick dust, or covering
with piece of linen cloth. or even pa.
per, or by simply shading them to les.
sen the evaporation. Cracks on the
side NAV be filled in with tow or cot
ton. When piing timber. place laths
or sticks of uniform size Mt uniform DIS
lal.cc under each log or post or tie.