The screws used by carpenters, smiths, and others, for fastening wood or metal-work together, are generally made by machinery. A piece of wire of the required thickness and length is first cut off, which is then placed in a hole or mould, with its upper orifice “countersunk” as in the annexed cut, and the head of the screw is formed by beating the upper part of the piece of wire into the counter-sinking of the mould. It is then called a “blank,” and a number of these blanks are dropped into holes bored round the periphery of a wheel which revolves slowly against a small circular saw driven with great rapidity, and cutting a “thread” or slit in the head of each blank in turn as it comes into contact with it; the wheel continuing to revolve, each screw when it gets to the bottom drops out, so that the holes when they again arrive upwards are ready to receive fresh blanks. The worm, if cut by hand, is made by means of a die of hard steel, having a hollow screw cut in it, which is screwed slowly by a backward and forward movement on to the blank, cutting it into a “worm;” when this is done by machinery, the die is held fast while the screw is worked by a rotatory movement into it. The best screws for wood are slightly tapered, which enables them to be driven much more easily, while they hold equally fast. Large screws for mechanical purposes are cut by a “lathe,” the bar revolving whilst a cutter is held to it, and moved onwards by a pattern screw. Small screws for various purposes can be easily cut by means of a “screw-plate,” having holes of graduated sizes cut inside into hollow screws, which is placed on the end of the wire, and gently turned round till it is sufficiently cut. PINS. Illustration: PIN-MAKING MACHINE. Illustration: COIL FOR THE HEADS.