In former times, engravers’ blocks were cut parallel with the grain, the present system of cutting them across the grain being introduced about the middle of the last century. In the preparation of a block, say for a newspaper plate, the parallelograms before spoken of are assorted as to size and fitted together at the back by brass bolts and nuts. So accurately do the edges of the wood fit together, that after the artist has finished his drawing on the smooth face of this compound block, the screws and bolts are loosened, and the pieces separated and given to several men to engrave the design; all that is needed after they have finished their work being to fit the pieces together and screw them up again, when they form one engraved block ready for the printing-press. Turkey boxwood, from a region of country in the vicinity of the Black Sea, is used for fine engravings. The best is of a delicate yellow colour free from spots or “eyes,” and cuts smoothly without crumbling or tearing. The tools or gravers necessary in wood-engraving are of three kinds,—viz., gravers proper (_a_); tint tools (_b_); and scoopers, or cutting-out tools, for clearing out the larger pieces (_c_). They are arranged in different sizes, to suit the various portions of the work.[9] [Illustration] According to Vasari, the important discovery of chalcography or engraving on brass or copper was made by Tommaso Finiguerra, a Florentine goldsmith of the fifteenth century, who lived from 1400 to 1460. The manner in which he made this discovery is thus stated by the Rev. T. F. Dibdin:— “Of engraving upon copper, the earliest known impression is that executed by one Tommaso Finiguerra, a goldsmith of Florence, with the date of 1460 upon it. One of the following circumstances is supposed to have given rise to the discovery. Finiguerra chanced to cast, or let fall, a piece of copper, engraved and filled with ink, into melted sulphur; and, observing that the exact impression of his work was left on the sulphur, he repeated the experiment on moistened paper, rolling it gently with a roller. This origin has been admitted by Lord Walpole and Mr. Landseer; but another has been also mentioned by Huber. ‘It is reported,’ says he, ‘that a washerwoman left some linen upon a plate or dish on which Finiguerra had just been engraving, and that an impression of the subject engraved, however imperfect, came off upon the linen, occasioned by its weight and moistness.’” PHOTO-ENGRAVING. Photo-engravings are produced by means of photography. It is a fact worthy of note that experiments in photographic engraving gave rise to photography itself. The aim of Nicéphore Niepce, when he began his researches in 1813, was not only to fix the image obtained by the camera obscura on a plate of metal, but to convert this plate into an engraving which could be used on a printing-press. His early death prevented his perfecting the process to which he had devoted much time and study.