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Northrop, E. B.; Chittenden, H. A., Jr. (ed.) / The Wisconsin lumberman, devoted to the lumbering interests of the northwest
(July, 1874)

Classification of wood,   pp. 393-397 PDF (1.8 MB)

Page 394

1 ,
394                  The Wisconinu
dry. Itsstrength across the grain,
and its resistance to crushing, are
comparatively great; and these pro-
perties render it useful for some
parts of mechanism, such as cogs of
wheels and shells of ships' blocks.
There are other European species of
elm, such as the Wych Elm (UImus
montana); but their timber is in-
ferior to that of the two species
A North American species, the
Rock Elm, is said to be not only
durable under water, but straight-
grained and tough, so as to be well
suited for framing.
LARGE RAYs coNTnmwD.-The kinds of
timber mentioned in this Article are
examples of the second subdivision
of Tredgold's second division, having
no large distinct medullary rays, and
no distinct difference of compactness
in the rings. This uniformity of
structure is accompanied by compara-
tive freedom from warping; and
hence this subdivision contains vari-
ous sorts of wood which are specially
well adapted both for framing and
for moving pieces in machinery,
where accuracy and constancy ol
form are required.
I. Mahogany (Swietenia Mahagoni)
is produced in Central America and
the West India Islands-that of .the
former region being commouly
known as "Bay Mahogany;" that oc
the latter, as "Spanish Mahogany.'
When of good quality, it is ver.
straight-grained, very strong in al
directions (though easily split aloni
the grain), very durable, and pre
serves its shape under varying cir
cumstances as to heat and moisture
better than any other kind of tim
ber which can be procured in equi
abundance. Mahogany varies muc
in quality; bay mahogany being i
general superior to Spanish mahoj
any in strength, stiffness, and dun
bilitv, and in the size of the log
which are from   24 to 28 inch4
square.  Bay mahogany of goc
quality is probably the best of a
timber for the framing of machinery.
Spanish mahogany is the more highly
valued for ornamental purposes.
Spanish mahogany is distinguished
by having a white chalky substance
in its pores, those of bay mahogany
being empty.
I. Lignum-vitbe (Guaiacum offwi-
nale) is produced in the West India
Islands. It is remarkable for heavi-
ness, compactness, toughness, and
hardness, and for the property of re-
sisting a crushing force with nearly
equal strength across and along the
grain-a property which makes it
specially useful for rollers, sheaves,
and other moving pieces in mechan-
ism. In converting logs into sheaves,
the direction of the fibre of the tim-
ber is parallel to the axis of the
sheave. The heart-wood is yellow-
ish-green, the sap-wood greenish-
yellow ; and it is considered advisa-
ble, in cutting it into pieces suitable
for sheaves, to leave a ring of sap-
wood all around the heart-wood,
which is thus protected against too
rapid drying, and prevented from
* splitting. I
Properties similar to those of Lig-
* num- vitan are box-wood
(Buxus sempervtirens), Ebony (Brya
ebenus, and other genera and spe-
dcies), Ironwood (Mesua Nagaha), and
various other woods, chiefly tropicaL
The subdivision embraces various
f kinds of timber grown in tropical
." climates, which are highly valued for
F shipbuilding purposes, and which
1 would be suitable also for the fram-
3g ing of machines-such as the Teak
(Tectona grandis) and Saul (Shorea
robusta) of India, and the Green-
e, heart (Nectanda Bodiwi), Mora (Mora
L- excelsa), and Sabicu (Acacia proxima)
d of South America and the West
h Indies.
n    SEASONS@.-Seasoning timber con-
,- sist in expelling, as far as possible,
r- the moisture which is contained in
a, its pores.
as     atural Seasoning is performed
ld simply by exposing the timber freeiy
ai to the kir in a dry place, sheltered,
k    i

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