nearly 43 feet,—the Oedrela odorata, which emits 
an aromatic fragrance, and is never attacked by 
insects, and sometimes attains a height of 150 
feet and a diameter of 64 feet,—the Bombax pen- 
tandrum, which, at even 60 years of age, has 
been known to have a girth of 26} feet, and to 
spread its boughs over a circular area of 120 feet 
in diameter,—the Zamang, a species of mimosa, 
which has been known to have a girth of 29 feet, 
and to spread its boughs over a circular area of 
about 204 feet in diameter,—and the Hymenca 
courbaru, which, though as hard as mahogany, | 
and in as great request among cabinet-makers 
and inlayers, sometimes attains the enormous 
diameter of 19 feet. The principal deciduous 
hardwood trees grown in British plantations are 
the oak, the elm, the ash, the sycamore or plane, 
the beech, the hornbeam, the Spanish chestnut, 
the horse chestnut, the walnut, the wild cherry, 
the maple, the lime, the laburnum, the hawthorn, 
and the mountain ash; the principal deciduous 
aquatic trees are the birch, the alder, the abele, 
the aspen, the black poplar, the Lombardy poplar, 
the elder, the willow, and the hazel; the only 
deciduous coniferous tree is the larch; and the 
principal evergreen trees, whether coniferous or 
otherwise, are the Scotch pine, the Weymouth 
pine, the black Austrian pine, the spruce, the 
common silver fir, the cedar of Lebanon, the yew, 
the holly, and the box. The peculiar properties 
and economical adaptations of the several kinds 
of timber are, in most instances, fully stated in 
the articles on the several genera or species. 
All timber, when in a recently felled state, 
contains a large proportion of water, and is liable 
to shrinking, cracking, and eremacausis; and, 
before it can be profitably or wisely used for al- 
most any purpose in the arts, it requires to be 
protected against these evils by a process of 
seasoning. This process, when left wholly or 
principally to the operation of natural causes, 
consists merely in the evaporation of the con- 
tained moisture of the timber into the atmo- 
sphere, and is at first comparatively rapid, and 
afterwards comparatively slow, and at all times 
accelerated or retarded by varying degrees of 
exterior heat and humidity; and, when duly 
favoured by such a position of the timber as ex- 
poses all its sides uniformly and equably to the 
evaporating action, it either renders the timber 
perfectly proof against all change dependent in 
any way on moisture, or permits it to be affected 
only by prolonged and constant wetness or by 
the mere hygrometric state of the atmosphere. 
The removing of the bark twelve months before 
felling, has been tried asa a method of seasoning 
oak and larch and perhaps some other species ; 
but, at some seasons, if not in all, it will be found 
rather to soften the alburnum than to harden it. 
The subjecting of cut and sawn timber to a strong 
heat by means of steam has been still more ex- 
tensively tried; and is regarded, in some de- 
partments, as a rapid, economical, and efficient 
TIMBER. 
substitute for the tedious method of natural sea- 
soning, but has been abandoned in others as un- 
suitable or as too expensive. 
logs in water, during a year or two previous to 
the process of natural drying, has been exten- 
sively tried in other departments, and is believed 
to dissolve out certain deliquescent salts, to bring 
the timber into the completest possible state of 
seasoning, and, not only to prevent it from 
shrinking and decomposing, but to fortify it 
against the erosions of insects and fungi. 
sink fresh-cut timber in water, with a view to 
prevent it from splitting, apparently in conse- 
quence of drying too quickly. The old Vene- 
tians sank, for a season in the sea, the oak tim- 
ber which was destined for the construction of 
their gallies. Hlm and beech, in particular, are 
said to improve greatly by the process of sub- | 
mersion in salt water, and to dry afterwards 
perfectly by simple exposure to the air. Mr. 
John Knowles, who made a particular study of 
the means most generally employed in seasoning 
timber, has given an account of a series of ex- 
periments undertaken in the arsenals of Dept- 
ford and Woolwich, to determine the rate of 
drying and ultimate degree of dryness attained 
by timber variously treated,—-unprepared and 
prepared by previous submersion in water. The 
pieces of timber were placed vertically, now in 
the position they had occupied in growing, now 
in that opposed to this; and it was found that, 
circumstances the same, they dried more quickly 
in the former than in the latter. The general 
results of these experiments were, that the pieces 
of timber were best seasoned by being kept about 
thirty months in the air, but in the shade and 
protected from wet,—and that they lost more of 
their original weight after six months’ alternate 
immersions and dryings, than by being kept 
under water for six months and then dried. 
Ship-builders are generally agreed that it is not 
expedient to make use of timber until three years 
after it is cut.” 
Three principal causes produce decay in felled 
or dead timber, seasoned or unseasoned,—and 
these are the action of eremacausis, the feeding of 
insects, and the growth of fungi; and all require 
the conditions of sufficient warmth, sufficient 
moisture, and stagnant air in order to their 
coming into play. The first is a slow and im- 
perceptible combustion, of great power, explained 
in the article Errmacausis; and the second and 
the third, though seeming at first sight to be 
trivial, really possess overwhelming energy, and 
can speedily reduce the stoutest timber to a mass 
of mere dust. The rapidity with which wood is, in 
some circumstances, devoured by insects is almost 
incredible. Some years ago the thermites, or white 
ants, spread in such strength through the docks 
and arsenals of Rochelle and Rochefort, that in 
a very short space of time serious damage was 
done. A learned entomologist, M. Audouin, 
The immersion of | 
Today | 
warm countries especially, it is advantageous to | 
