SEAL ENGRAVING

The art of engraving gems is one of extreme nicety. The stone having received its desired form from the lapidary, the engraver fixes it by cement to the end of a wooden handle, and then draws the outline of his subject, with a bra needle or a diamond, upon its smooth surface. IMG:4147767755307473660_illo1096.png:Engraver Fig. 969. represents the whole of the seal engraver’s lathe. It consists of a table on which is fixed the mill, a small horizontal cylinder of steel, into one of whose extremities the tool is inserted, and which is made to revolve by the usual fly-wheel, driven by a treddle. The tools that may be fitted to the mill-cylinder, are the following: fig. 970. a hollow cylinder, for describing circles, and for boring; fig. 971. a knobbed tool, or rod terminated by a small ball; fig. 972. a stem terminated with a cutting disc, whose edge may be either rounded, square, or sharp; being in the last case called a saw. Having fixed the tool best adapted to his style of work in the mill, the artist applies to its cutting point, or edge, some diamond-powder, mixed up with olive oil; and turning the wheel, he holds the stone against the tool, so as to produce the wished-for delineation and erosion. A similar apparatus is used for engraving on gla . In order to give the highest degree of polish to the engraving, tools of boxwood, pewter, or copper, bedaubed with moistened tripoli or rotten-stone, and lastly, a brush, are fastened to the mill. These are worked like the above steel instruments. Modern engravings on precious stones, have not in general the same fine polish as the antient. The article Gems , in Rees’ Cyclopædia, contains a variety of valuable information on this subject, equally interesting to the artist and the scholar.