gone almost entirely out of use, having been—like engraving in imitations of drawings in chalk or pencil—in a great degree superseded by lithography.
Mezzotint is said to have been invented by Prince Rupert, or by Leivis Siegen, a lieutenant in his service, in or about 
Fig. 2.—The Rocker. the year 1611, and to have been suggested by the rust on a weapon which a soldier was cleaning.
The plate is prepared (before any design is made upon it) by means of an instrument or tool called the "rocker" (see Fig. 2). This "rocker" is rocked to and fro upon the plate in all directions, and the teeth in the sharp, beveled edge of the tool make a small dent in the copper or steel and raise a corresponding "burr." The whole plate is gone over with this instrument about eighty times before it is in a fit condition to be worked upon. When sufficiently prepared it presents a fine, soft-looking, and perfectly even grain, and if in this state a proof is taken from it by the usual process of plate printing the result is the richest possible black.
On this plate, after a tracing has been transferred, the engraver goes to work, with tools called "scrapers" and "burnishers," working from dark to light by removing the dents and burrs, and exactly in proportion as he removes them the tint becomes paler and paler, those parts most smoothed being the lightest and the part the least operated on producing the deepest shadows. As the process is from dark to light, the engraver has to be very cautious not to remove too much of his grain at once, for once he has it too light it would be impossible to restore the color without destroying the surrounding lights. He proceeds from dark to half dark, from half dark to middle tint, from middle tint to half light, and from half light to light. When the work is good the result is soft and harmonious, well adapted to the interpretation of some painters, but not of all.
More than one hundred engravers in mezzotinto employed themselves on the portraits of Sir Joshua Reynolds, and the best of their works are now valued as the classics of the art which is connected with the name of Reynolds, just as line engraving is connected with that of Raphael.
In engraving in "stipple," which was much in vogue in the
