NEEDLE MANUFACTURE. This useful little article constitutes a large business, giving employment to many hundred operatives. The following is an outline of the various processes carried out : The best steel, reduced by a wire-draw ing machine to the suitable diameter, is the material of which needles are formed. It is brought in bundles to the needle factcry, and carefully examined. For this purpose, the ends of a few wires in each brindle are cut off, ignited, and har dened by plunging them into cold water. They are now snapped between the fin gers, in order to judge of their quality; the bundles belonging to the most brittle wires are set aside, to be employed in making a peculiar kind of needles.
After the quality of the steel wire has been properly ascertained, it is calibred by means of a gauge, to see if it be equal ly thick and round throughout, for which purpose merely some of the coils of the bundles of wires are tried. Those that are too thick are returned to the wire drawer, or set apart for another size of needles.
The new made coil is cut in two points diametrically opposite, either by hand shears, of which one of the branches is fixed in a block by a bolt and a nut, or by means of the mechanical shears, the crank of which is moved by a hydraulic wheel, or steam power, and rises and falls alternately. The extremity of this crank enters into a mortise cut in the arm of a bent lever, and is made fast to it by a bolt. An iron rod, hinged at one of its extremities to the end of the arm, and at the other to the tail of the shears or chisel, forces it to open and shut alternately. The operative placed upon the floor, presents the coil to the action of the shears, which cut it into two bundles, composed each of 90 or 100 wires, up wards of 8 feet long. The chisel strikes 21 blows in the minute.
These bundles are afterwards cut with the same shears into the desired needle lengths, these being regulated by the di ameter. For this purpose the wires are put into a semi-cylinder of the proper length, with their ends at the bottom of it, and are all cut across by this gauge.
The wires, thus cut, are deposited into a box placed alongside of the workman.
Two successive incisions are required to cut 100 wires, the third is lost. Hence the shears, striking 21 blows a minute, cut in 10 hours 400,000 ends of steel wire, which produce 800,000 needles. The cut wires are bent, and have to be made straight ; this is done by passing a flat iron plate or rule with great force once or twice over the cut bundles.
The wires are now taken to the point ing-tools, which usually consist of about 80 grindstones arranged in two rows, driven by a water-wheel. Each stone is about 18 inches in diameter, and 4 inches thick. As they revolve with great velo city, and are liable to fly in pieces, they are partially incased by iron plates, hav ing a proper slit in them to admit of the application of the wires. The workman seated in front of the grindstone, seizes 50 or 60 wires between the thumb and forefinger of his right hand, and directs one end of the bundle to the stone. By means of a bit of stout leather called a thumb-piece, the workman presses the wires, and turns them about with his fore finger, giving them such a rotatory mo tion as to make their points conical. This operation, which is called roughing daunt is dry grinding ; because, if water were made use of, the points of the need les would be rapidly rusted. It has been observed long ago, that the silicious and steel dust thrown off by the stones, was injurious to the eyes and lungs of the grinders ; and many methods have been proposed for preventing its bad effects. The machine invented for this purpose by Mr. Prior, does away with much of this evil.
The flatted heads have become harden ed by the blow of the hammer ; when an nealed by heating and slow cooling, they are handed to the piercer. This is com monly a child, who, laying the head upon a block of steel, and applying the point of a small punch to it, pierces the eye with a smart tap of a hammer, applied first upon the one side, and then exactly opposite upon the other.