ENGRAVING UPON GLASS

ENGRAVING UPON GLASS. See GLASS, Engraving on.
ENGRAVING

(E) Although we are now contemplating linear engraving, it is but proper here to observe, that chalk engraving, mezzotinto, and aquatinta, have also made ample improvements in this country, in their various styles, of excellence.

Engraving. ENGRAVING on Precious Stones, is the representing of figures, or devices, in relievo, or indented, on divers kinds of hard polished stones.

The art of engraving on precious stones is one of those wherein the ancients excelled; there being divers antique agates, cornelians, and onyxes, which surpass any thing of that kind the moderns have produced. Pyrgoteles among the Greeks, and Dioscorides under the first emperors of Rome, are the most eminent engravers we read of; the former was so esteemed by Alexander, that he forbade any body else to engrave his head; and Augustus's head, engraven by the latter, was deemed so beautiful, that the succeeding emperors chose it for their seal.

All the polite arts having been buried under the ruins of the Roman empire, the art of engraving on stones met with the same fate. It was retrieved in Italy at the beginning of the 15th century, when one John of Florence, and after him Dominic of Milan, performed works of this kind no way to be despised. From that time such sculptures became common enough in Europe, and particularly in Germany, whence great numbers were sent into other countries; but they came short of the beauty of those of the ancients, especially those on precious stones; for, as to those on crystal, the Germans, and, after their example, the French, &c. have succeeded well enough.

In this branch of engraving, they make use either of the diamond or of emery.

The diamond, which is the hardest of all stones, is only cut by itself, or with its own matter. The first thing to be done in this branch of engraving is, to cement two rough diamonds to the ends of two sticks big enough to hold them steady in the hand, and to rub or grind them against each other till they be brought to the form desired. The dust or powder that is rubbed off serves afterwards to polish them, which is performed with a kind of mill that turns a wheel of soft iron. The diamond is fixed in a brass dish; and, thus applied to the wheel, is covered with diamond dust, mixed up with oil of olives; and when the diamond is to be cut facet-wise, they apply first one face, then another, to the wheel. Rubies, sapphires, and topazes, are cut and formed the same way on a copper wheel, and polished with tripoli diluted in water. As to agates, amethysts, emeralds, hyacinths, granites, rubies, and others of the softer stones, they are cut on a leaden wheel, moistened with emery and water, and polished with tripoli on a pewter wheel. Lapis-lazuli, opal, &c. are polished on a wooden wheel. To fashion and engrave vases of agate, crystal, lapis-lazuli, or the like, they make use of a kind of lathe, like that used by pewterers, to hold the vessels, which are to be wrought with proper tools: that of the engraver generally holds the tools, which are turned by a wheel: and the vessel is held to them to be cut and engraved, either in relievo or otherwise; the tools being moistened from time to time with diamond dust and oil, or at least emery and water. To engrave figures or devices on any of these stones, when polished, such as medals, seals, &c. they use a little iron wheel, the ends of whose axis are received within two pieces of iron, placed upright, as in the turner's lathe; and to be brought closer, or set further apart, at pleasure: at one end of the axis are

fitted the proper tools, being kept tight by a screw. Engraving. Lastly, The wheel is turned by the foot, and the stone applied by the hand to the tool, and is shifted and conducted as occasion requires.

The tools are generally of iron, and sometimes of brass; their form is various, but it generally bears some resemblance to chisels, gouges, &c. Some have small round heads like buttons, others like ferrets, to take the pieces out, and others flat, &c. When the stone has been engraven, it is polished on wheels of hair-brushes and tripoli.

ENGRAVING on Steel is chiefly employed in cutting seals, punches, matrices, and dyes, proper for striking coins, medals, and counters: The method of engraving with the instruments, &c. is the same for coins as for medals and counters: All the difference consists in their greater or less relievo; the relievo of coins being much less considerable than that of medals, and that of counters still less than that of coins.

Engravers on steel commonly begin with punches, which are in relievo, and serve for making the creux or cavities of the matrices and dyes: though sometimes they begin with the creux or hollowness; but then it is only when the intended work is to be cut very shallow. The first thing done, is that of designing the figures; the next is the moulding them in wax, of the size and depth they are to lie, and from this wax the punch is engraven. When the punch is finished, they give it a very high temper, that it may the better bear the blows of the hammer with which it is struck to give the impression to the matrice.

The steel is made hot to soften it, that it may the more readily take the impression of the punch; and after striking the punch on it in this state, they proceed to touch up and finish the strokes and lines, where by reason of their fineness or the too great relievo they are any thing defective, with steel gravers of different kinds; chisels, flatters, &c. being the principal instruments used in graving on steel.

The figure being thus finished, they proceed to engrave the rest of the medal, as the mouldings of the border, the engrained ring, letters, &c. with little steel punches, well tempered, and very sharp.