Page:Encyclopædia Britannica, Ninth Edition, v. 14.djvu/690

 060 LINEN sists of a series of narrow heckle bars, with short closely studded teeth, which travel between the feed rollers and the drawing or &quot;boss and pressing&quot; rollers to be immediately attended to. They are, by an endless screw arrange ment, carried forward at the rate at which the flax is delivered to them, and when they reach the end of their course they fall under, and by a similar screw arrangement are brought back to the starting point ; and thus they form an endless moving level toothed platform for carrying away the flax from the feed rollers. The drawing rollers grip the fibre as it leaves the gill, and, as they revolve much more rapidly than the feeding rollers, the fibre is drawn out through the gill teeth say to twenty or thirty times the length it had on the feeding board, and is con sequently reduced to a sliver or loose ribbon of correspond ingly greater tenuity. The sliver from the drawing frame is delivered into a tin can which holds 1000 yards, and the machine automatically rings a bell when that length is delivered. From the spreading frame the cans of sliver pass to the drawing frames, where from four to twelve slivers combined are passed through feed rollers over gills, and drawn out by drawing rollers to the thickness of one. A third and fourth similar doubling and drawing may be embraced in a preparing system, so that the number of doublings the flax undergoes, before it arrives at the roving frame, may amount to from one thousand to one hundred thousand, according to the quality of yarn in progress. Thus, for example, the doublings on one preparing system maybe 6x12x12x12x8 = 82,944. The slivers delivered by the last drawing frame are taken to the roving frame, where they are singly passed through feed rollers and over gills, and, after drafting to sufficient tenuity, slightly twisted by flyers and wound on bobbins, in which condition the material termed &quot;rove&quot; or &quot;rovings&quot; is ready for the spinning frame. The preparation of tow for spinning differs in essential features from the processes above described. Tow from different sources, such as scutching tow, heckle tow, &c., differs considerably in quality and value, some being very impure, filled with woody shives, &c., while other kinds are comparatively open and clean. A pre liminary opening and cleaning is necessary for the dirty much- matted tows, and in general thereafter they are passed through two carding engines called respectively the breaker and the finisher cards till the slivers from their processes are ready for the drawing and roving frames. In the case of fine clean tows, on the other hand, passing through a single carding engine may be sufficient. The processes which follow the carding do not differ materially from those followed in the preparation of rove from line flax. Spinning, The spinning operation, which follows the roving, is done in two principal ways, called respectively dry spinning and wet spinning, the first being used for the lower counts or heavier yarns, while the second is exclu sively adopted in the preparation of fine yarns up to the highest counts manufactured. The spinning frame does not differ in principle from the throstle spinning machine used in the cotton manufacture (see COTTON, vol. vi. p. 495). The bobbins of flax rove are arranged in rows on each side of the frame (the spinning frames being all double) on pins in an inclined plane A (fig. 2). The rove passes downwards through an eyelet or guide I to a pair of nipping rollers p, p, between which and the final drawing rollers c, c, placed in the case of dry spinning from 18 to 22 inches lower down, the fibre receives its final draft while passing over and under cylinders d and guide-plate g, and attains that degree of tenuity which the finished yarn must possess. From the last rollers the now attenu ated material, in passing to the flyers /, receives the degree of twist which compacts the fibres into the round hard cord which constitutes spun yarn ; and from the flyers it is wound on the more slowly rotating spool e within the flyer arms, centred on the spindle S. In wet spinning the general sequence of operations is the same, but the rove, as unwound from its bobbin, first passes through a trough of water heated to about 120 Fahr. ; and, moreover, the interval between the two pairs of rollers in which the draw ing out of the rove is accom plished is very much shorter. The influence of the hot water on the flax fibre ap pears to be that it softens the gummy principle which binds the separate cells to gether, and thereby allows the elementary cells to a certain extent to be drawn out without breaking the continuity of the fibre ; and further it makes a finer, smoother, and more uniform strand than can be obtained by dry spinning. The ex tent to which the original strick of flax as laid on the feeding roller for (say) the production of a 50 lea yarn is, by doublings and draw ings, extended, when it reaches the spinning spindle, may be stated thus : 35 times on spreading frame, 15 times on first drawing frame, 15 times on second drawing frame, 14 times on third drawing frame, 15 times on roving frame, and 10 times on spinning frame, in all 16,537,500 times its original length, with 8x 12 x 16 = 1536doublings on the three drawing frames. That is to say, 1 yard of heckled line fed into the spreading frame is spread out, mixed with other fibres, to a length of about 9400 miles of yarn. In the case of fine yarns, by the additional drawings given, the doublings and elongations are very much greater. The next operation is reeling from the bobbins into hanks. By Act of Parliament, throughout the United Kingdom the standard measure of flax yarn is the &quot;lea,&quot; called also in Scotland the &quot; cut &quot; of 300 yards. The flax is wound or reeled on a reel having a circumference of 90 inches (2^ yards) making &quot;a thread, &quot; and one hundred and twenty such threads form a lea. The grist or quality of all fine yarns is estimated by the number of leas in a pound ; thus &quot; 50 lea &quot; indicates that there are 50 leas or cuts of 300 yards each in a pound of the yarn so denomi nated. With the heavier yarns in Scotland the quality is indicated by their weight per &quot; spindle &quot; of 48 cuts or leas ; thus &quot; 3 ft&amp;gt; tow yarn &quot; is such as weighs 3 ft&amp;gt; per spindle, equivalent to &quot;16 lea.&quot; The hanks of yarn from wet spinning are either dried in a loft with artificial heat, or, in rural localities, exposed over ropes in the open air. When dry they are twisted back and forward to take the wiry feeling out of the yarn, and made up in bundles for the market as &quot; grey yarn.&quot; English and Irish spinners make up their yarns into &quot;bundles&quot; of 20 hanks, each hank containing 10 leas; Scotch manufacturers, on the other hand, adhere to the spindle containing 4 hanks of 12 cuts or leas. Commercial qualities of yarn range from about 6 tt&amp;gt; tow yarns (8 lea) up to 160 lea line yarn. Very much finer yarn up even to 400 lea may be spun from the system of machines found in many FIG. 2. Section of Dry Spinning Frame.