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DIAMOND.
75
tal plate of cast iron, fourteen or fifteen inches in diameter, (called a skive,)[1] fixed on aspindle, and capable of being put into rapid motion by means of a larger wheel, five or six feet in diameter, and turned by an assistant. In order to -keep the Diamond perfectly steady while the polishing: of each facet is going on, the following contrivance is had recourse to. .A copper cup (called a dopp,) about three quarters of an inch in depth and the same in width, and furnished with a stem about four inches long, of stout copper wire, is filled with plumber's solder, which projects in a conical form beyond the rim of the cup: in the apex of this cone, the solder being softened by heat, the diamond is imbedded with the facets to be po-
- ↑ The surface of the plate is roughened by the application of a grit-stone, in order that it may better retain the mixture of olive-oil and diamond-powder, with which the skive is charged, and which is renewed, as occasion requires.
