Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/700

Rh 660 WOOL [MANUFACTURE. drafting. The twist is given in the reverse direction from that in which the singles are spun, and thereby the single is to some extent untwisted. Yarns of two-, three-, and five-ply and upwards are made ; these are sometimes redoubled or again twisted together. The yarn may be made up of precisely the same singles; sometimes diil erent counts or sizes of singles are twisted together; in other cases the colours may be different; and yet again yarns may be made of distinct fibres, such as wool and cotton, or wool and silk, &c. Numerous variations of the method of twisting are employed to pro duce loops, knots, and other irregularities in the yarn, for con venience in weaving and knitting i aucy textures. Worsted If we adhere to the definition of worsted yarn which distin- yarn. guishes it as being made from wool fibres brought as far as possible into a level parallel condition, we shall have to do only with two methods of manufacture, (1) of yarn from long wool by the method of drawing, gilling, and combing, and (2) of yarn from medium and short staple wools, which are first carded and afterwards combed. But there is commonly added a third class of worsted yarns, worsted only in the sense that they are not meant for felting. These are carpet yarns and lightly twisted knitting yarns, which, being meant to be full and open in structure, are prepared for spinning by carding alone, precisely as in making woollen yarns. Combing. The primitive method of wool-combing, and the simple imple ments employed till comparatively recent days, when the ingenious machinery now used was invented, will serve to illustrate the problem of preparing long wool for spinning. The hand combs employed were studded with two sometimes three rows of long, smooth, rounded, and sharp-pointed steel spikes. The operative was provided with a pair of these combs. He had a comb-post to which he could attach them, and a comb-pot or small stove in which he heated the teeth of his combs and the wool which he worked. The teeth of one comb being duly heated he fixed it in the comb-post, and taking a quantity of wool previously oiled he dashed it in portions into the teeth of the comb and drew it through, leaving a portion locked in the spikes, and this operation he continued till the comb was well filled with wool. Then he placed it in the comb-pot to heat up, while he similarly proceeded to iill the teeth of the second comb, which in the meantime had been heating. With both filled and duly heated, he took one comb in his left hand, laying it in his lap teeth upwards, and with the other in his right he proceeded to comb out the locks, beginning first at the tips and working gradually in as the fibres were smoothed and opened out. In the end the combs were worked with teeth close up to each other and through the entire mass, the noils or short fibre being thus entirely combed out, excepting a small quantity left in the teeth which could not be reached by the opposing combs. The typical modern process in worsted-yarn fabrication is that in which the preparation consists in gilling and subsequent comb ing, as practised when long wool is the staple to be treated. The object of gilling is to bring all the fibres level and parallel to each other, and to prepare a uniform sliver for the subsequent combing operation. The gilling-machine or gill-box (fig. 7) in its essen tial features consists first of a pair of rollers to which the wool is FIG. 7. Screw Gilling Machine. fed. Beyond these it is caught by rows of steel pins fixed in heavy steel bars, termed fallers, which rise in close and constant succession immediately behind the feed-rollers, penetrate the wool presented to them, and travel forward with it towards a second pair of rollers which catch the fibre and draw it away. The spike-covered fallers are so called because they travel from one to the other pair of tollers, carried forward by endless screws into which they are threaded, then, falling down, are returned by the action of similar screws operating in the opposite direction, till just under the feed- rollers they rise again to catch the feed of wool, and so continue to circulate. There is thus a continuous line of fallers travelling be tween feed-rollers and back rollers, but as the back rollers revolve much more quickly than the front rollers, and also draw the wool through them more rapidly than it is presented to them by the fallers, there is a constant and steady drawing of wool away from the front rollers and through the teeth of the fallers, and this draught tends to cause all the fibres to arrange themselves in the direction in which they are being gently dragged. A set of gill- boxes consists of five or six machines constructed on the same principle, but with the pins of the fallers finer and more closely studded as the fibre travels on and as the orderly and symmetrical arrangement of the sliver increases. Prom the first two or three machines the wool is generally delivered as a broad lap, and it is similarly presented to the next, but in the later boxes the pro duct is condensed into a sliver, which is received in large cylin drical tin cans. Six of these cans are brought to the front of the next gill-box, and the six slivers are, in passing through, drawn into and delivered as one, and, such an operation being repeated three times, it will be seen that any original portion of sliver must be distributed over a great length, and in this way the fibres are brought even with each other and a very level and uniform strand is produced. In the original form of gill-box the fallers travelled from front to back at a uniform speed, and thus all the draughting was done by the rapid rotation of the back rollers. Now, by a graduated pitch in the screws which carry the fallers forward, they travel at a steadily accelerated rate, beginning slow, and reaching their greatest rapidity just as they deliver the w r ool to the back rollers, which revolve still more rapidly. Thus there is steady draughting throughout the whole range of the machine, and the wool is at once more gently treated and more uniformly drawn out than in the old forms of the machine. It will be obvious that the gill-boxes through which long wool passes, while possessing the power of bringing the fibres into a smooth, equal, and regular condition, do nothing in the way of selecting and separating out the long and straight from the short and curly fibres which are always intermixed. To obtain an even, and smooth worsted yarn it is necessary to effect this separation, and it is the function of the various forms of combing machine now in use to separate the &quot;top&quot; or long fibre from the &quot;noil&quot; or short and broken wool, and to deliver the former as a continuous sliver of uniform size. The invention of a successful combing machine has been the great triumph of the modern worsted in dustry, and the introduction of the apparatus led, as is commonly the case with all great inventions, to a vast amount of dispute anil litigation, and many conflicting claims of merit. About 1840 at least three investigators were separately at work on the problem Mr S. C. Lister of Bradford, Mr Donisthorpe of Leicester, and M. Heilmann of Alsace. Messrs Lister and Donisthorpe conjointly ecured a patent for a combing machine, in connexion with which they entered into partnership, but their patent rights were success fully disputed by Heilmann under a patent granted to him in 1847, and they were obliged to buy up his invention for 30,000. Since that time much attention has been given to combing machinery, not for wool alone, but also for spun silk and cotton ; and now there are many varieties of apparatus in the market for doing what not very long ago was pronounced to be utterly impracticable. The three principal classes of machine at present used for wool-combing are (1) the Lister or nip machine, which is most suitable for long combing wools, mohair, and alpaca ; (2) the Noble or circular comb, principally useful for combing shorter staple or intermediate wools ; and (3) the Holdeii or square-motion comb, which is applicable for short staple wools. It is impossible here to convey a full con- eption of the delicate almost intelligent manner in which these machines work. A principal feature of them is a large ring or circle studded with rows of fine steel pins, which is made to revolve horizontally within the machine. By various devices the wool is Fed into the teeth of the ring in a continuous series of tufts with its ends overlapping the edge of the ring as it revolves. In the case of the nip machine the wool is fed in by fallers as in the gill- box. The end of the sliver is caught by a nip which tears a tuft through the pins of the fallers, and thus partly combs it out. This tuft the nip places on the teeth of the revolving circle, by which it is carried on till it comes to a pair of upright rollers revolving close to the edge of the circle. These rollers catch between them the ends of the long fibre and draw it out of the teeth of the circle in a continuous sliver as it revolves. The Noble or circular comb is provided with three pin-studded rings, one large and two small, the latter being so centred within the larger ring that in rotating their outer edges just meet the inner edge of the large ring which rotates around them. The tufts of wool are dabbed down over the pins of the larger and smaller circles at the points where they meet, and of course as they rotate the teeth immediately begin to draw apart, and the wool is divided, the long fibres hanging over the edge of each circle. These fibres are caught between upright