RUBBERS. - The rubbers used in polishing often follow very nearly the form of the plane, the file, or the turning tool, accordingly as the respective artizans use the plane, file, or turning tool in their several avocations. For instance, the carpenter wraps glass paper around a square flat piece of cork; the smith and others using files, fold emery paper upon that instrument, or use, after the manner of the file, square pieces of wood and metal fed with the several powders mixed with oil, and they also employ either the sides or the sloping ends of square slips of the polishing stones.

Many of the turned works in the metals, etc. are polished with pointed sticks of deal, by the ends of which the gritty substances are forcibly applied as the work revolves.

2. - The Rubber used by Masons and Statuaries is frequently a slab of grit stone, to which a handle is attached by means of an iron strap, or cement. Sometimes the handle is short and perpendicular, at other times long and horizontal, or inclined at a small angle or loosely attached by an eye bolt, and stones of two or three qualities, from coarse to fine, are used in succession. The same forms are also given to the handles of flat plates of iron and lead that are fed with sharp sand for polishing stone, or with emery for metal; and the plate may in this case be made of such a weight as to supply the required pressure, leaving to the workman alone to put it in movement to and fro upon the work, with strokes evenly distributed throughout its surface.

3. - The Block or Cloth Rubber used for Marble, consists of a wooden block about 12 or 14 inches long, 3 to 6 wide, and 2 to 3 thick, a hole is bored through the wood at one end for a transverse stick or handle which projects,horizontally on both sides, and there are fillets of wood on the top by which lumps of lead are temporarily affixed to give the required pressure. Felted cloth nearly half an inch thick, (called nap,) is fixed below the rubber by folding the cloth a little way up the ends and nailing it, or thinner woollen and also one or more layers of coarse linen cloth are also used according to the degree of hardness required.

4. - Large Cloth Rubbers for polishing marble are sometimes made of woollen or other rags placed in a rectangular iron frame, connected by two side screws which compress the rags into a dense mass, the surface of which is allowed to wear itself flat or it is levelled with a red-hot iron; sometimes the ring is entire and the rags are fixed by wedges, at other times the ring is in two parts and connected by side screws to produce the compression, and a socket is added for the attachment of the handle by which the rubber is moved. 5. - Small Cloth Rubbers or Rollers, used for various purposes in polishing, are commonly made of a coil of list or the selvedge of woollen cloth, wound up spirally to the diameter of two to four inches and tied round tightly with string. They are usually covered with a cloth of some kind that may easily be renewed. 6. - Rubbers for French Polishing are made of little balls of wadding, (that used for ladies dresses,) covered with a linen rag. The rubber is placed on the open mouth of the bottle which is then turned up, the varnish thus collected is covered with a second rag, and moistened with one or two drops of linseed oil, the varnish gradually exudes according to the degree of pressure given to the ball, which is of about the size of a walnut, and is thrown away after four or five minutes' use, as it hardens from the accumulation of the varnish and then scratches instead of polishing the work.