Their specimens are distinguished by low relief, a granular border surrounding the engraving, stiffness in the figures, peculiar style of letters and writing, wings given to the deities which the Greeks represent without wings, and names generally attached to the figures. The Greeks also practised chiefly in intaglio, and some of their finest works are in chalcedony and carnelian. The highly famed Dionysiac bull of Hyllus, an artist supposed to have lived before the age of Augustus, is upon chalcedony; and a celebrated specimen in carnelian is the beautiful seal which once belonged to Michel Angelo, and was afterward preserved in the national library at Paris. The engraving represents a vintage, but the design has been referred in various learned dissertations to a number of different objects, some of mythological character. Many impressions and copies have been taken of this famous specimen. The engraved gems of the first 15 centuries A. D., excepting the imitations of antique works, generally have designs from Scriptural subjects -images of Christ and of the Virgin Mary, representations of the Good Shepherd, and often a fish, symbolical of the Saviour, from the letters in its Greek name, being the initial letters in the appellation

Some terms employed to designate certain styles of antique gems may be properly noticed here before speaking of the art in modern times. Stones convex on one side are said to be en cabochon; chimaerae are those with representations of imaginary beings made up of portions taken from different animals; grylli are those with hideous heads, said to be so called from an Athenian named Gryllus, who was extraordinarily ugly; conjvgata, or joined, are those with heads represented together upon the same profile, called opposite when they face each other. Engraving was practised both in intaglio and in rilievo, and the two styles were sometimes combined in the same specimen. Stones having differently colored layers, like the onyx, were especially adapted for the rilievo style, for an account„of which see Cameo. - In modern times the finest gem engravers are found among the Italian artists of the 18th century, and chiefly those of Florence. Some of their works are hardly inferior to those of the most famous Grecian artists. Flaviano Sirletti of Florence, who died in 1737, was especially distinguished for his copies of ancient gems and exact imitations of the ancient letters.

The Costanzis and many others also attained great repute; and in the present century are some whose productions, as those particularly of Signor Rega of Naples, rank with the famous antique gems. Among the Germans, Daniel Engelhard of Nuremberg, a friend of Albert Diirer, was celebrated for his skill in engraving crests and arms. He died in 1552. The works of the Pichlers, father and son, who came from Tyrol, are of the highest merit, especially those of the father. The son was much in Italy, and is often spoken of as an Italian. The celebrated Poniatowski collection of antique gems has recently been credited to the elder Pichler. Natter of Swabia, who died in 1763, was not only a workman of the most delicate skill and refined taste, but a student and author also, and published in 1754 a treatise specially devoted to his art: Traite de la methode antique de graver en pierres fines comparee avec la methode moderne. From this work it appears that the ancients employed the same sort of tools and the same methods as those in use at the present day.

The modern practice is described by Holtzapffel in vol. iii. of his Mechanical Manipulation."-The apparatus employed in engraving consists of a foot lathe attached to a small table, upon which is fixed a little pillar for holding the horizontal pulley, which is the receptacle for the cutting tool. This part of the apparatus is called the mill. The tools are soft iron wire spindles carefully annealed and nicely fitted to the hollow axis of the pulley. Only one is used at a time. When set in its place it projects through the bearings of the pulley, one end extending horizontally on the right-hand side of the operator, who sits at his work in front of the table. This extremity of each tool is fashioned for its special work. Most of them terminate in a small disk, the edge of which, as it rotates rapidly, cuts lines in the stone held up against it, the tool being fed with diamond dust and oil. The larger sized disks are only about a quarter of an inch in diameter, and from this they are made of decreasing sizes down to 1/150 of an inch, when the disk can scarcely be distinguished by the eye from the stem. They are also variously shaped for special kinds of cutting. The stone intended to be engraved is usually shaped by the Lapidary, and is sometimes set by the jeweller before it is engraved.

If not set, the engraver secures it to a wooden handle by the cement known as the lapidary's; or if set, he secures it in a notch in a piece of cork. The polish is removed by roughening the face with a suitable cutting powder, as the tools work better upon a rough surface, and the outline of the design, which is next marked with a brass point, is the more conspicuous. The area thus enclosed is then sunk by the tools to a suitable depth; and within this the details of the design are successively introduced and excavated. For the parallel lines, called color lines, a thicker disk with two cutting edges is employed, its form being that of a little pulley; the two edges are just as far apart as the lines they are intended to cut, and as one pair is cut the stone is moved so as to bring the outer edge of the disk into the groove marked by the other edge, and thus the work goes on step by step over the surface to be thus colored." The plan must be perfectly understood by the artist at the commencement of his work, and as it goes on he watches the effect produced with the aid of a magnifying glass conveniently attached to a stand over the tool, and occasionally takes a proof of his work in wax.