The common pin is of brass with a tinned surface. Pins now are turned out by automatic machines in such quantities that the cost of manufacture is slightly greater than the value of the brass wire from which they are made. A single machine does the work. Coils of wire, hung upon reels, are passed into machines which cut them into proper lengths, and they drop off into a receptacle and arrange themselves in the line of a slot formed by two bars. When they reach the lower end of the bars they are seized and pressed between two dies, which form the heads, and pass along into the grip of another steel device, which points them by pressure. They are then dropped into a solution of sour beer, whirling as they go, to be cleaned, and then into a hot solution of tin, which is also kept revolving. They here receive their bright coat of metal, and are pushed along, killing time, until they have had an opportunity to harden, when they are dropped into a revolving barrel of bran and sawdust, which cools and polishes them at the same time. Because of the oscilla tion of the bran they work gradually down to the bottom of the barrel, which is a metallic plate cut into slits just big enough for the body of the pins, but not big enough for the head to pass through. Thus they are straightened out
into rows again, and, like well drilled soldiers, pass along toward the edge of the bottom, and slide down an inclined plane, still hanging by their heads, until they reach strips of paper, to which they are introduced by a curious jerk of the machine. The first they know they are all placed in rows, wrapped up and on their way to the big department stores, where they are sold at a small price. A machine is expected to throw out several thousand gross an hour. Hairpins and safety pins and other kinds of pins are all manufactured by somewhat similar special machinery.
The word pin is applied in mechanics to any relatively small straight piece of metal that serves to join parts. The crank-pin of a great steamship's mainshaft may weigh a ton, where as a pin in a watch-plate may be difficult to discern. A wooden pin is now more commonly called a peg. Both needles and hairpins are manufactured to a greater extent in Europe than plain pins. Safety pins, however, are decidedly American, and of these we make on an average 1,000,000 gross a year.