Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/490

Rh 464 WEAVING is exhausted. The contents of several beams filled from bobbins may be required to be rewound together on a single beam to supply the requisite quantity of ends for a web. Plain Weaving. The warp beam thus filled is laid in the loom (fig. 1), and the ends of warp are then separately drafted or drawn through a pair of heddles or healds. The essential features of the FIG. 1. Diagram of Hand-Loom. heddle are the eyes, loops, or mails through which the warp is threaded, one end of warp only passing through any mail. This eye or mail is placed in the heddle half-way between an upper and a lower wooden sheaf, over which pass the heald threads or between which extend the wires on which such mails are supported. The distance between the mails and the lathes at each end must be sufficient to allow of that opening or &quot;shedding&quot; of the warp which it is the function of the heddle to secure. Through the mails of one heddle each alternate end of warp is drafted, and the remaining ends are passed similarly through the other. Thus each heddle receives every alternate thread across the whole breadth of the warp. From the heddles the ends are carried through the reed (fig. 2), which is the ultimate distributor of the warp, and the instrument by which the weft is beaten up and closed in weaving. It consists FIG. 2. Weaver s Reed. of an oblong narrow frame filled with fine strips of cane or of flat tened brass or steel wire, these strips being placed in fine comb-like order more or less closely together, up to as many as 120 strips or &quot;dents,&quot; or even more, per inch; two or more ends are passed through each slit of the reed, which is fixed in a &quot;lay&quot; or &quot;batten,&quot; a suspended frame for moving the reed backward and forward in beat ing up the weft. On the lower part of the batten a ledge projects, which forms the &quot;shuttle race &quot; for carrying the shuttle in &quot; pick ing&quot; from and to the shuttle boxes at each end of the lay. From the reed the ends are carried forward and fastened to the cloth beam, and now the warp is ready for the weaving operation. The three essential movements in weaving are (1) the &quot;shed ding &quot; or dividing of the warp threads to permit of the passage between them of the shuttle containing the weft ; (2) the picking &quot; or shooting of the weft ; and (3) the &quot; battening &quot; or beating up of the weft. The shedding motion depends upon the heddles, which are corded or attached to a pair of treadles worked by the weaver s feet. Each treadle is connected with the heddles above and below by a system of levers or pulleys, so that the depression of one treadle while it raises one heddle depresses the other, and thus the opening or shed is made in the warp, one-half consisting of alternate threads being raised, the corresponding half pulled down. The weaver then with the left hand pushes the lay or batten back towards the heddles, till a sufficient portion of the shed is brought in front of the reed, and the depressed ends lie just over the shuttle race. A clear way is thus provided for picking or shooting the shuttle, which is done with a whipping jerk of the picking stick held in the right hand. This pulls the cord attached to the picker and projects the shuttle from one shuttle box into that at the opposite end of the lay. The lay is now drawn forward with the left hand, and the reed combs and beats up the weft thread. Treadle number two is next depressed and thereby a new shed is formed, the last made pick or shoot being enwrapped between the intersecting warp sheds ; the lay is again thrown back, the pick of weft is shot and beaten up, and so on in regular succession (see fig. 3). In plain weaving it is possible to produce stripes by the use of bands of coloured warp, and checks where both warp and weft are particoloured. In the latter case shuttles, or at least cops, equal in number to the different colours of weft required, must be pro vided. It is obvious that the repeated changing of shuttles, and at FIG. 3. Section of plain web in process of weaving on the loom : a, warp beam ; 6, leash rods where the warp is divided and crossed; c, c, heddlea; d, reed ; e, the woven cloth ; /, the cloth beam. still more the withdrawing and replacing of cops in weaving with frequently changing weft, would occasion great loss of time. To avoid that, and to provide for the use of different coloured wefts, or of wefts of various counts, the drop box was invented, a device by which two or more shuttles can be successively used in any order desired. The drop box, and its numerous subsequent modi fications of circular and other change boxes, consists of a series of compartments or divisions in the shuttle box, each made to hold a separate shuttle. These several compartments are by mechanical agency brought in line with the shuttle race in the order in which the changes of weft picks are necessary. Twill Weaving, So long as only two sets or leaves of treadles are used in a loom very little in the form of a pattern can be pro duced, seeing no variation can be effected in the alternate raising of each heddle. To a limited extent a corded surface may be pro duced by passing two or three warp ends through each mail, and by throwing two or three picks of weft between each shed. But for effective figure- weaving there must be numerous possible variations of shed ; and that is secured first by increasing the number of heddles in the loom. Thus with three heddles alone it is possible to effect six combinations of shedding, and as the number of heddles is added to the variations of possible shedding increase in geo metrical ratio. But the number of treadles which can be corded up to separate heddles is in practice limited, and therefore only simple twill patterns are for the most part woven with treadles and heddles. A twill is a cloth in which the warp and weft do not intersect alternately, but where the warp predominates on the one side and the weft on the other. The simplest of all is the three - leaf twill, in which the warp passes over two and under one welt thread, and vice versa, in regular succession, giving the appearance of a succession of diagonal lines on the surface. Regular twills of from four to eight leaves are woven in the same manner, the weft rising over each fourth to eighth warp thread as the case may be. Many variations and combinations are possible in connexion with these regular twills. For example, they may be combined with plain weaving: a cashmere twill may be made, that is, a four-leaf com bination, in which the weft passes alternately over and under two warp ends, and two picks are shot for each shed. Further, zig-zags, lozenges, squares, and other geometrical designs can be produced by reversing the order of the treading, and thereby causing the twill to run in different directions. The diagrams, figs. 4 and 5, show two arrangements of a four-leaf twill, the first being a regular twill and the second a dimity, the dark squares representing the point at which the weft rises to the. Fi e- 4 - Fi - 5 - surfaces. Satin or broken twills are those in which the warp threads are not intersected by the weft in regular succession, but only at intervals, and thereby the smooth continuous surface characteristic of satin and damask is secured. Com mon satin and double damask are eight- leaf twills, the order in which the weft rises being shown in the diagram, fig. 6. Rich satins may consist of sixteen to twenty leaf twills, the weft intersecting and binding down the warp at every sixteenth to twentieth pick as the case may be. Satins are usually woven with the face of the cloth downwards, be cause in weaving, say a sixteen-leaf satin, it would be necessary were the surface upwards to keep fifteen heddles Fig. 6. raised and one down, whereas, with the face of the cloth under, only one heddle has to be raised at a time. Figure Weaving. Only a limited number of heddles can in actual working be attached each to a separate treadle to be under the control of the feet of the weaver. But to produce a complicated