ORIGIN OF THE CURLS IN WOOD.

35

would be likewise a most wasteful method of cutting up the timber; it is therefore only resorted to for thin veneers, when some particular figure or arrangement of the fibres, has to be obtained for the purposes of ornamental cabinet-work.

The perpendicular cut through the heart of the tree is not. only the hardest but the most diversified, because therein occur the greatest mixture and variety of the fibres, the first and the last of which, in point of age, are then presented in the same plank; but of course the density and diversity lessen as the board is cut further away from the axis. In general the radial cut is also more ornamental than the tangental, as in the former the medullary rays produce the principal effect, they are then displayed in broader masses, and are considered to contain the greater proportion of the colouring matter of the wood.

The section through the heart displays likewise the origin of most of the branches, which arise first as knots, in or near the central pith, and then work outwards in directions corresponding with the arms of the trees, some of which, as in the cypress and oak, grow out nearly horizontally, and others, as in the poplar, shoot up almost perpendicularly.

Those parts of wood described as curls, are the result of the confused filling in of the space between the forks, or the springings

of the branches. Fig. 9 represents the section of a piece of yew-tree, which shows remarkably well the direction of the main stem A B, and the origin of the branch C, and likewise

the formation of the curl between B and C; in many woods, the mahogany especially, the curls are particularly large, handsome and variegated, although distinctly similar as to origin. The fig. 10 is the end view of the stem at A.

It would appear as if the germs of the primary branches were set at a very early period of the growth of the central stem, and gave rise to the knots, many of which however fail to penetrate to the exterior so as to produce branches, but are covered over by the more vigorous deposition of the annual rings. All these knots and branches, act as so many disturbances and interruptions to the uniformity of the principal zones of fibres, which appear to divide to make way for the passage of the off-shoots, each of which possesses in its axis a filament of the pith, so that the branch resembles the general trunk in all respects except in bulk, and again from the principal branches smaller ones continually arise, ending at last in the most minute twigs, each of which is distinctly continuous with the central pith of the main stem, and fulfils its individual share in causing the diversity of figure in the wood.

The knots are commonly harder than the general substance, and that more particularly in the softer woods; the knots of the deals, for example, begin near the axis of the tree, and at first show the mingling of the general fibres with those of the knot, much the same as in the origin of the branch of the yew in fig. 9, but after a little while it appears as if the branch, from elongating so much more rapidly than the deposition of the annual rings upon the main stem, soon became entirely detached, and the future rings of the trunk were bent and turned slightly aside when they encountered the knot, but without uniting with it in any respect.

This may explain why the smooth cylindrical knots of the outer boards of white deal, pine, &c., so frequently drop out when exposed on both sides in thin boards; whereas the turpentine in the red and yellow deals may serve the part of a cement, and retain these kinds the more firmly.

The elliptical form of the knots in the plank, is mostly due to the oblique direction in which they are cut, and their hardness, (equal to that of many of the tropical hard woods,) to the close grouping of the annual rings and fibres of which they are themselves composed. These are compressed by the surrounding wood

ROOTS; POLLARD TREES.

37

of the parent stem, at the time of deposition; whereas the principal layers of the axis of the tree are opposed alone by the loosened and yielding bark, and only obtain the ordinary density.

The knots of large trees are sometimes of considerable size. I have portions of one of those of the Norfolk Island pine, (Araucaria excelsa,) which attained the enormous size of about four feet long, and four to six inches diameter. In substance it is throughout compact and solid, of a semi-transparent hazelbrown, and it may be cut almost as well as ivory, and with the same tools, either into screws, or with eccentric or drilled work, &c.; it is an exceedingly appropriate material for ornamental turning*.

It is by some supposed that the root of a tree is divided into about as many parts or subdivisions as there are branches, and, that speaking generally, the roots spread around the same under ground, to about the same distance as the branches wave above; the little germs or knots from which they proceed being in the one case distributed throughout the length of the stem of the tree, and in the other crowded together in the shorter portion buried in the earth.

If this be true, we have a sufficient reason for the beautiful but gnarled character of the roots of trees when they are cut up for the arts; many a block of the root of the walnut-tree, thus made up of small knots and curls, that was intended for the stock of a fowling-piece, has been cut into veneers and arranged in angular pieces to form the circular picture of a table, and few of this natural kind will be found more beautiful. The roots of many trees also display very pretty markings; some are cut into veneers, and those of the olive-tree, and others, are much used on the Continent for making snuff-boxes.

The tops of the pollard trees, such as the red oak, elm, ash, &c., owe their beauty to a similar crowding together of the little germs, whence originate the numerous shoots which proceed from them after they have been lopped off. The burrs or excrescenses of the yew, and some other trees, appear to arise from a similar cause, apparently the unsuccessful attempts at the forma

* I am indebted to Maj. Brown for my specimens of this knot, and the information concerning it; a part of a knot of the same species, with some of the surrounding wood, is in the model-room of the Admiralty, Somerset House.

38

BURRS OR WENS; KIABOOCA, MAPLE, ETC.

tion of branches from one individual spot, whence may arise those bosses or wens, which almost appear as the result of disease, and exhibit internally crowds of knots, with fibres surrounding them in the most fantastic shapes. Sometimes the burrs occur of immense size, so as to yield a large and thick slab of highly ornamental wood of most confused and irregular growth: such pieces are highly prized, and are cut into thin veneers to be used in cabinet-work.

It appears extremely clear likewise, that the beautiful East Indian wood, called both kiabooca and Amboyna, is, in like manner, the excrescence of a large timber tree. Its character is very similar to the burr of the yew, but its knots are commonly smaller, closer, and the grain or fibre is more silky. It has also been supposed to be the base of the cocoa-nut palm, a surmise that is hardly to be maintained although the latter may resemble it, as the kiabooca is imported alone from the East Indies, whereas the cocoa-nut palm is common and abundant both in the eastern and western hemispheres. (See KIABOOCA in the Catalogue*.)

The bird's-eye maple, shows in the finished work the peculiar appearance of small dots or ridges, or of little conical projections with a small hollow in the center, (to compare the trivial with the grand, like the summits of mountains, or the craters of volcanoes,) but without any resemblance to knots, the apparent cause of ornament in woods of somewhat similar character, as the burrs of the yew and kiabooca, and the Russian maple (or birch tree), &c.; this led me to seek a different cause for its formation.

On examination, I found the stem of the American bird's-eye maple, stripped of its bark, presented little pits or hollows of irregular form, some as if made with a conical punch, others ill-defined and flattened like the impression of a hob-nail; suspecting these indentations to arise from internal spines or points in the bark, a piece of the latter was stripped off from another block, when the surmise was verified by their appearance. The

I have a beautiful specimen of a Burr, found occasionally upon the teak, which is fully equal in beauty to the Amboyna, but a smaller figure; I owe it to the kindness of Dr. Horsfield of the India-House.

Mr. G. Loddiges considers the burrs may occur upon almost all old trees, and that they result from the last attempt of the plant to maintain life, by the reparation of any injury it may have received.

BIRD'S-EYE MAPLE, ETC.

39

layers of the wood being moulded upon these spines, each of their fibres is abruptly curved at the respective places, and when cut through by the plane, they give, in the tangental slice, the appearance of projections, the same as in some rose-engine patterns, and the more recent medallic engravings, in which the closer approximation of the lines at their curvatures, causes those parts to be more black, (or shaded,) and produces upon the plane surfaces, the appearances of waves and ridges, or of the subject of the medal.

The short lines observed throughout the maple wood, between the dots or eyes, are the edges of the medullary rays, and the same piece of wood when examined upon the radial section, exhibits the ordinary silver grain, such as we find in the sycamore, (to which family the maple tree belongs,) with a very few of the dots, and those displayed in a far less ornamental

manner.

The piece examined measured eight inches wide, and five and a half inches radially, and was apparently the produce of a tree of about sixteen inches diameter; the effect of the internal spines of the bark was observable entirely across the same, that is through each of the 130 zones of which it consisted. The curvature of the fibres was in general rather greater towards the center, which is to be accounted for by the successive annual depositions upon the bark, detracting in a small degree from the height or magnitude of the spines within the same, upon which the several deposits of wood were formed. Other woods also exhibit spines, which may be intended for the better attachment of the bark to the stem, but from their comparative minuteness, they produce no such effect on the wood as that which exists, I believe exclusively, in the bird's-eye maple.

This led me to conclude, that the figure in woods, which resembles the appearance of undulations, or the ripple mark on the sands, that is frequently observed in satin-wood and sycamore, less frequently in box-wood, and also in mahogany, ash, elm, &c., to be due to a similar cause, namely a serpentine or guilloche form in the grain : and on inspection, the fibres of all such pieces will be found to be wavy, (as in fig. 11,) on the face, at right angles to that on which the ripple is observed, if not on both faces. Those parts of the wood which happen to receive the light, appear the brightest, and form the ascending sides of