This invention is admirably adapted to the prevention of forging bank notes, as by this means several first rate artists may be employed at one time to produce portions of a plate in detached parts, which may afterwards be combined and arranged in any order to produce a single plate, and before the note could be imitated by forgers it may be called in and a new note issued, consisting of the same parts differently arranged; the principle, also, offers various other mode: of defeating attempts at imitation. The invention has accordingly been very extensively patronized by the banks in America from its outset; and at the present time the notes of most of the provincial banks in this country are produced by this process, some of them presenting the most beautiful specimens of the art of engraving ever witnessed. The bank of England, however, for reasons which are variously stated, has declined availing itself of the advantages which the plan holds out, and after going to an expense of more than 30,000f. in endeavouring to improve the quality of its notes, and to render them more difficult of imitation, still continues to issue the same wretched description of notes as have been so extensively and successfully counterfeited for many years past.

Wood Engraving is a process which is the reverse of copper-plate engraving, for in the latter, the incisions made in the metal receive the ink and print the design, while in the former, the raised parts form the design, receive the ink, and transfer the subject to the paper. Accordingly, in engraving a block of wood, the subject of which is to be represented by black lines, all those parts of the space occupied by the design, which are not drawn upon, are entirely cut away, whilst all the permanent lines of the drawing are left untouched by the graver, as shown in the subjoined profile sketch of a face. In work of this kind it is obvious that the engraver can easily produce a perfect fac-simile of the artist's drawing; in fact, his manual skill only is exercised to leave the lines of the design untouched, by carefully cutting away all the wood, and so deep that no other part of the block shall take the printer's ink from the dabber or roller, and that the paper in printing shall not reach the sunken parts.

The process of clearing away the wood without damaging the lines of the drawing, is, of course, a nice operation; nevertheless, a learner in the space of two or three months acquires such dexterity with his little tools, that he cuts away nearly as fast as he can move his hand or fingers. Before, however, the engraver commences to "clear out" his work he "outlines it," which consists in carefully running a very sharp narrow-pointed graver along both sides of the lines of the drawing; this insures more accuracy and clearness in the subsequent operation, and to prevent the back of the graver from injuring the lines of the design, the engraver occasionally in difficult parts defends the lines by covering them with a thin piece of metal, which he holds down upon the work with the fingers of his left and. A much easier, and therefore cheaper mode of engraving on wood, is to make white line3 on a black ground, as represented in the engraving on the next page.

In this case the block of wood is supposed, as in the former case, to have the profile drawn upon it, but instead of leaving the artist's lines upon the wood, he cuts them away alone, leaving the rest of the wood the same true plane it was before. The latter, therefore, receives the ink, and delivers it upon the paper, while the incisions, taking up no ink, leave their traces like white lines upon the paper. This mode of engraving on wood is, therefore, analogous to that upon copper plates, but the inking is different; as in the latter case the ink is rubbed into the lines or incisions, leaving the surface clean, and therefore the lines only of the copper plate are imprinted. The taste of a wood engraver is most exercised in softening the shadows and graduating the lights of his subject A consideration of the following sketch will explain to the reader the principle upon which the engraver works. In the upper figure the strong light upon the top of it is produced by first cutting down in mass the upper surface at that part, by shelving or inclining the sides to the cavity made, so that when the parallel straight lines or tint is cut, their extremities become so extremely fine and tapering, that they can scarcely receive or deliver any ink, by their being sunk below the plane of the other parts.

In the distance it will be noticed that the lines are very near together, to give the effect of distance, while those in front are comparatively wide apart, to give the effect of nearness. These different spaces are produced by gravers of different breadths of point. For this purpose the engraver provides himself with six or eight tinting gravers, which he numbers from 1 to 6 or 8, taking them up and changing them in his work as the subject requires. In the figure underneath, it will be seen that a strong light and a very deep shadow are brought very near together, but without offending the eye by too great abruptness. This is effected by continuing the white lines of the light part by lines of diminished thickness over the black or solid part, with a fine graver. A very close imitation of copper engraving may be made upon wood, so as to have great force and clearness in some kind of subjects, but can only be afforded by the engraver when he is duly paid for the great extra labour attending it. This consists in crossing the lines in the manner shown by a little bit at a, in the bottom corner of the preceding figure.

The diamond-shaped pieces are every one picked out by the graver, and these, in some fine wood engravings, are extremely minute; nevertheless, the lines, however fine, are left clear and unbroken. To show the freedom, ease, rapidity, and consequent cheapness with which white lines may be executed upon a black ground, we have added the annexed illustrated cut, which was executed by an expert engraver in the space of three or four minutes. The wood made use of is mostly box, the best of which comes from Turkey. The tree is cut into slices transversely to the grain, and then rendered to a true plane and smoothed. On this fine compact surface the subject is drawn, either with black lead pencil or with Indian ink; but the latter is preferable (except for works of high finish), as it is not so liable to be effaced during the process of engraving. The art of engraving on wood is coeval with the art of printing, in Europe, the earliest books being printed from wooden blocks, each block comprising a page, as is the method at the present day in China, in which country the art, it is said, has been practised so far back as the christian era.

After flourishing for a time in Europe, the art seems to have fallen into neglect, from which it was first rescued in England by the celebrated Bewick, since whose time it has risen gradually in repute and eminence, and now occupies a respectable station amongst the fine arts. The superior utility of wood engraving consists in the great durability of the blocks, but more especially in the peculiar advantage it possesses of ranging with type, and being printed with it; which renders it particularly adapted for the illustration of mathematical and mechanical subjects, as the necessary diagrams and figures can be introduced in the body of the letter press, wherever it is most convenient for the elucidation of the subject. The blocks may likewise be stereotyped along with the type, as is now very generally practised with standard works.