TIMBER. 
series of medullary rays; the primary ones are 
large and strongly marked, distant from each 
other, and are uninterrupted in their course from 
the pith to the bark; the secondary rays are 
numerous between the primary, but not crowded. 
The concentric layers, or circles, are distinguished 
by the arrangement of the cells; they are grouped 
in somewhat triangular masses, forming a wavy 
circular outline. The structure of the concen- 
tric layers or annual rings, distinguishes at once 
with certainty the wood of the oak from that of 
the chestnut, with which it has often been con- 
founded.—The ash has the places of those rays 
so prominent on the wood of the oak, supplied by 
twin rays placed in wide intervals over the sur- 
face; and between these double rays are smaller 
ones, placed in regular order. In the narrow 
spaces between the individuals which constitute 
the twin rays are wanting those apparent remains 
of the cellular texture which are so remarkable 
in the spaces between the single rays.—The beech 
has the primary rays dispersed pretty regularly 
over the surface of a horizontal section of the 
wood; the secondary rays are not continuous 
from the pith to the bark, but interrupted, and 
exhibit a numerous series of fragments of rays, 
filling up the spaces between the primary ones, 
obvious to the naked eye, and rendering the sil- 
ver grain very distinct from that of any other 
kind of wood.—The Spanish or sweet chestnut 
agrees with the oak in having the secondary rays 
equally disposed, almost straight, and, though 
close to each other, yet not crowded as in the 
elm and the beech; but it differs, in the primary 
rays being scarcely to be distinguished from the 
secondary, whilst in the oak these are prominent 
and obvious to the naked eye on the slightest 
inspection,—in the concentric layers being regu- 
larly curved, whilst in the oak they are strikingly 
waved,—and in the mouths of the tubular ves- 
sels, which constitute so obvious a part of these 
annual rings or layers, being in regular order, 
while in the oak they are disposed in triangular 
masses. — The hornbeam has the rays nearly 
equal, but may readily be distinguished from the 
beech, to which it bears the greatest resemblance, 
by the simple arrangement of the tubular struc- 
ture accompanying the concentric layers, which 
in the hornbeam are distant and oval-shaped, 
the narrow sides pointing to the pith and to the 
bark, while in the beech they are circular-shaped, 
more numerous, and equal-sized.—The birch has 
all the medullary rays nearly equal, arranged 
closely, and the concentric circles minute, but 
marked with a row of equal cells—The horse 
chestnut has all the rays very minute, few of 
them apparently continuous, but interrupted, 
and in substance varying in breadth. The cells 
are numerous and minute.—The alder has large 
primary rays, thinly arranged, but in nearly re- 
gular order, and the secondary rays slender, nu- 
merous, and interrupted. The cells of the con- 
| 
eee a ee ee 
centric layers are nearly regular. The spaces 
450 
between the rays are crowded with cells.—The 
oriental plane has the primary rays regular but 
closely arranged, and somewhat wavy, and the 
cellular texture of the concentric layers but 
slightly marked.—The sycamore in texture ap- | 
proximates to the plane, yet is very distinct in 
its straight lined rays, which are very minute or 
slender. The cellular texture is composed of 
such minute cells as scarcely to be perceptible 
under a four-power microscope; these cells are, | 
however, very numerous.—The poplar has the 
wood composed of rays so slender as not to be 
obvious to the naked eye. The concentric layers 
are composed of exceedingly minute cells. This 
wood is extremely porous; the cells of which it 
is composed are so numerous that a very thin 
slice of the wood, taken horizontally, exhibits 
the appearance of the finest possible open net- 
work.—The common acacia, or locust, bears some 
resemblance to the oak ; but it wants the distinct 
primary rays so prominent in the oak, and has 
its rays nearly all of equal breadth, and as slen- 
der as the secondary rays of the oak, and some- 
what wavy. Thecellular or tubular structure is 
also very different from that of the oak, the cells 
being arranged in more regular order where 
they mark the concentric layers; and the spaces 
between the rays are furnished with many cells 
irregularly scattered over, of a size equal. to those 
marking the concentric layers.—The fir is dis- 
tinguished by very prominent coloured concentric 
layers, arranged very regularly throughout; and 
the cellular texture, though composed of cells 
sufficiently large to be seen with the naked eye, 
is not to be distinguished without very close ob- 
servation.—The lime has very slender equal rays, 
and a minute cellular texture pervading the 
whole body of the wood. The concentric layers 
are scarcely perceptible to the naked eye. It 
may be compared to the poplar ; but the network- 
like arrangement of the cellular texture is not 
so obvious; and the presence of the rays readily 
distinguishes it—The laburnum is distinguished 
by its minute, regular, uninterrupted medullary 
rays, and by the broken beaded longitudinal 
lines of the tubular structure. 
Timber trees are conveniently classified, by 
practical men, into foreign and domestic, or such 
as will not and such as will grow and prosper in 
the plantations of Britain; and the latter may 
be subclassified into deciduous hardwood trees, 
deciduous aquatic trees, larches, and evergreen 
trees. Foreign timber-trees yield most of the 
fancy woods used in cabinet work and for fine or 
small ornamental purposes; and some of them, 
notwithstanding their rare beauty and reputed 
scarceness, attain a great size in the natural 
forests of the tropics; and among these are the 
mahogany tree, which sometimes acquires a di- 
ameter of upwards of 6 feet,—the wood of St. 
Martha, which is very hard, and has a deeper 
colour and a more beautiful appearance than 
mahogany, and sometimes attains a diameter of 
