THE materials used in turning and the mechanical Arts are exceedingly numerous: we obtain from the Vegetable Kingdom an extensive varietyof woods of different characters, colours, and degrees of hardness, and also a few other substances.

The most costly and beautiful products of the Animal Kingdom, are the tusks of the elephant, the tortoise and pearl shells; but the horns, hoofs, and some of the bones of the ox, buffalo. and other animals, are also extensively used for more common purposes.

From the Mineral Kingdom are obtained many substances which are used in their natural states, and also the important products of the metallic ores.

It would be altogether misplaced to attempt a minute and general description of these varied materials, as they will be found in their more appropriate places in works on natural his-tory, physiology, mineralogy, and metallurgy; and it is the less necessary, as those which are more commonly used, are familiar to us in the buildings, machinery, implements, furniture, and ornaments, by which we are surrounded: others of less extensive supply are, in many respects, only varieties which are subject to similar usage. I shall therefore principally restrict myself, to the description of those characters of the usual materials which lead the artisan to select them for his several purposes,and that also direct the choice of the tools by means of which they are respectively worked.

By far the most numerous and important of the materials form the Vegetable Kingdom arc the woods, with which most parts of our globe are abundantly supplied; great numbers of them are used in their respective countries, and are known to the naturalist, although but a very inconsiderable portion of them are familiar to us in our several local practices.

The woods that are the most commonly employed in this couutry, are enumerated in an alphabetical list, together with the most authentic information I could obtain concerning them; in collecting which, the assistance of various kind friends has been obtained, amongst whom are numbered travellers, naturalists, merchants and manufacturers. Various museums, collections, and works, have been carefully examined, so as to include in the list, the more important of the various names of the woods, their countries, general and mechanical characters, and their principal uses in the arts of construction.

The alphabetical catalogue is preceded by a tabular view, intended to classify the woods that are the most generally selected by our artisans for certain ordinary uses; it will also serve, in a slight degree, to throw them into groups according to some of the differences between them, referrible principally to their fibrous structures, by which they are distinguished as hard or soft, elastic or non-elastic, of plain or variegated appearance, of permanent figure or the reverse.

Their other varieties, in respect to colour and scent, and the oils, resins, gums, medicinal and various other matters, they respectively contain, are questions of equal importance, but they are more connected with the chemical and economic arts, and but slightly concern this inquiry. I shall therefore, nearly restrict myself to the questions arising from the mechanical structure and treatment of the woods, which it is proposed to consider under separate heads, in the present and three following chapters.

The general understanding of the principal differences of the woods will be greatly assisted by a brief examination into their structure, which is now so commonly and beautifully developed by the sections for the microscope. The figures 1, 2, 3 arc drawn from thin cuttings of beech-wood, prepared by the opticien for that instrument; the principal lines alone are repre-sented, and these are magnified to about twice their linear distances, for greater perspicuity.

Figs. 1.

Materials From The Vegetable Kingdom Section I The 1001

2.

Materials From The Vegetable Kingdom Section I The 1002

3.

Materials From The Vegetable Kingdom Section I The 1003

Fig. 1, which represents the horizontal or transverse section of a young tree or a branch, shows the arrangement of the annual rings around the centre or pith; these rings are surrounded by an exterior covering, consisting also of several thinner layers, which it will suffice to consider collectively, in their common acceptation, or as the bark. The fibres which are seen as rays proceeding from the pith to the bark, are the medullary rays or plates.

Figs. 2 and 3 are vertical sections of an older piece of beech-wood. Fig. 2 is cut through a plane, such as from a to a, in which the edges of the annual rings appear as tolerably parallel fibres running in one direction, or lengthways through the stem; the few thicker stripes are the edges of some of the medullary rays.

Fig. 8 is cut radially, or through the heart, as from b to b.

In this the fibres are observed to be arranged in two sets, or to run crossways; there are first the edges of the annual rings, as in fig. 2, and secondly, the broad medullary rays or plates.

The whole of these figures, but especially the last, show the character of all the proper woods, namely, those possessing two sets of fibres, and in which the growth of the plant is accomplished, by the yearly addition of the external ring of the wood, and the internal ring of the bark, whence these rings are called annual rings, and the plants are said to be exogenous, from the growth of the wood being external.

In fig. 1 the medullary rays are the more distinctly drawn, in accordance with the appearance of the section, as they seem to constitute more determinate lines; whereas the annual rings consist rather of series of tubes, arranged side by side, and in contact with each other, and which could not be represented on so small a scale. At the outer part of each annual ring these tubs or pores appear to be smaller and closer; the substance is consequently more dense, from the greater proportion of the matter forming the walls of the tubes; and the inner or the softer parts of the annual rings have in general larger ves-and therefore less density.