Engraving by dots has been for a long time practised, as by its means a graduated tone can be more easily obtained than it can by the use of line alone, and stipple is the same idea carried out by the etching needle instead of the graver. Stipple is done by means of small bunches of needles, with which irregular dots are made in the etching ground and then bitten by acid, as usual. In most cases a few small finishing dots are put on the copper by hand afterwards. Stipple is excellent for faces, and is best known in the work of Bartolozzi, who excelled in it. It is said to have been invented by Jacob Bylaert, a Dutchman, in 1760. In England stipple engraving was largely used in the early nineteenth century for book illustrations. It is found chiefly in faces, and is generally supported by line engraving or etching. The best stipple engravers did not illustrate books, but the work of W. Finden, C. Knight, J. Parker, C. Marr, and W. Holl is always good, though, of course, very small. Besides these there were numbers of lesser stipple engravers, whose work is fair--Jenkinson, Dean, H. Cook, C. Wagstaffe, H. Robinson, and many more. The same sort of usefulness was found for stipple abroad, for faces particularly, and it was successfully practised by Pfeiffer, Vangelisty, and others, but it never took the same hold upon the Continent that it did here, either in the case of small book illustrations or in the more important matter of large stipple engravings. Mezzotints are not satisfactory if they are on a small scale. Delicate and minute work cannot be done well by the mezzotint process alone, but require supplementary line or etched work. So we find that mezzotints have not been much used for book illustration. The process of mezzotinting was invented by Ludwig von Siegen, an officer in the Hessian Army, about 1642, and at first it was practised chiefly by foreigners, but it soon became the favourite method of engraving upon metal in England; indeed, the competition of the mezzotint eventually ruined the slower and more costly process of line engraving. Some books concerning mezzotints have explanatory plates in them, beginning with Le Blon’s “Coloritto,” written about 1721, but these can hardly be considered as fair instances of ordinary book illustrations. A copper plate is prepared for mezzotint engraving by being uniformly roughened all over, so that if it were inked and a print made from it, the print would show a uniform velvety black. The art of the “scraper” consists in so skilfully cutting away or burnishing down the roughened surface of the copper that when a print is made a picture appears. The scraper works from black to white whenever the surface is scraped or burnished away, so in exact correspondence the print will show grey or white. It is quick work, and easy work up to a point, but to make a first-rate mezzotint is a great art, and only a few engravers have succeeded in doing it.