shining surface, and rubs off any roughness. FILES. Illustration: FILE CUTTING. Files are among the most useful of tools for those who work in metals, and in many other substances, as ivory, or hard woods. A file consists of a bar of steel of various shapes, such as flat, square, three-cornered, round, and half-round; on the surface of this bar of steel small furrows are formed, with rough projections between them, and these are again, in most kinds of files, crossed with others. The mode of making a file is as follows:--A bar of wrought or cast steel is cut off of the requisite length and of the proper figure, and forged on an anvil to the required shape--that is to say, rather tapering at the top and brought to a point (called the “tang”) at the bottom, so that it may be driven into a wooden handle. The file has now to be cut. To do this requires great manual dexterity. A man sits before a bench, and passes a strap over each end of the file so as to steady it, and these are kept down with the feet. A small chisel of hard steel is held in the left hand between the thumb and finger and struck with a short-handled heavy hammer, the effect is to cut a notch, with an elevation at each side called a “burr;” the small chisel is slipped up to this “burr,” and struck again, and so on till the whole file is cut, and this with such rapidity that the eye can scarcely follow it. When the file is thus notched from end to end, it has to be hardened, which is done by making it red-hot and suddenly plunging it into cold water, which makes it so hard that it will scratch glass and cut away any other metal. Illustration: FILE. Illustration: RASP. For softer substances, such as wood, a kind of file is often used called a “rasp,” which, instead of having furrows cut on it, is struck into little dints by means of a three-cornered piece of hard steel, which, as it enters the file, throws up a projection also. For filing bone and ivory, a kind of file is used with very large notches, not crossed by others, the edge of each of which acts like a plane-iron or chisel, and takes off shavings from the bone. TYPE. Illustration: TYPE CASTING.