Twill Weave.— In the weaving of twills the interlacing is quite different from plain weave. Considering the shuttle as starting from the left hand, and the threads numbered consecu tively from left to right, the operation may be described thus: for the first pick the first thread of the warp is raised, allowing the shuttle to pass under it, the second and third threads being depressed so that the weft lies above them; the fourth thread is raised and the fifth and sixth are depressed—and so on. On the second pick, that is, as the shuttle comes back to its first position, the heddles are operated so that the second thread of the warp is raised. the third and fourth being depressed; the fifth raised, and the sixth and seventh depressed- and so on. As the shuttle starts away again from the left, the first and second threads are depressed and the third raised; the fourth and fifth depressed and the sixth raised — and so on; this completing the cycle. By this method of manipulating the heddles is produced the diagonally ribbed appearance of the surface of the cloth characteristic of twills. These rib bings appear on both sides of the cloth. They may trend either to the right or to the left (from the weaver). On the three-thread pat tern, as described above, only one variety of twill can be produced — that with the apparent ribbing on the diagonal of a square, that is, at -15°. But by using a four-thread pattern that is, by depressing three threads of warp great variety of silk, wool and cotton dress cloths. Patterns of the three fundamental straight twills on four threads are shown in the upper tier of Fig. 8, the 2-and-2 twill in the centre; the tier of pattern blocks just below them showing the reverse sides of the tipper blocks. Besides these straight twill weaves three other arrangements are possible through the manipulation of the heddles in an irregular fashion, thus producing what are called "broken twill0— used very largely in the weaving of the coarser lines of "dice° pattern; in many for each one raised, a modified twill is pro duced with a "flatter" diagonal, that is. at about 30° — away from the weaver. The cloth thus produced is called a "horizontal twill.° On the other hand the manipulation of the heddles may be such that three vertical meas ures of the warp may be left on the surface to each one covered by the weft, thus producing a "vertical twill," with the angle of the ribbing 711T.Iiing away (from the weaver) at about 60°.
Where four threads (of warp) and four picks (of weft) enter a design a much wider variety in texture is gained. In fact, next to the plain weave the 2-and-2 twills are the most extensively used in weaving; constituting the serges, cassimeres, most linen goods and a Cl "(FIG. 8.— Group of Four-thread Twill Patterns. woolen cloths; in double-faced cloths; and ex tensively as a base for various fancy weaves and for dotted fabrics. Patterns for these broken twills are shown in the lowest tier of Fig. 8. The twill weave can also be carried into five-thread patterns, and even greater skips, but with five threads the sateen weave becomes available, and is more commonly used. It is obvious that the direction of the ribbing in a twill may be changed at will from a right-hand trend to a left-hand trend during the process of weaving, and thus produce a zigzag pattern known as "herring-bonen or diaper — as shown in Fig. 9. In Fig. 10 is shown an elabo rate pattern of twill which may be worked on 10 heddles and with 10 treadles. One of the
chief advantages of the twill pattern is that a firm and substantial cloth may be thus woven from comparatively light yarns.
Sateen Weave.— In sateen weaving at least sateens: 3-and-5 and 5-and-3. In an 11 thread design eight different sateens are pos sible: 2-and-9, 3-and-8, 4-and-7. 5-and-6, 6-and-5, 7-and-4, 8-and-3, 9-and-2. As a prac tical limit in designing it may he mentioned that 24-thread patterns are in use for fine silks, though rarely for other materials.
Damasks.— In damask weaving the pattern is produced by arrangitiv that the warp in some parts of the fabric and the weft in others warp threads to he numbered consecutively from that side, the operation may he described as follows: the first, sixth, 11th, etc., threads are stitched on the first pick; the third, eighth, 13th, etc., on the second pick; the fifth, 10th, 15th. etc., on the third pick; the second, seventh, 12th. etc., on the fourth pick: and the fdarth ninth, 14th, etc.. on the fifth pick— thus cooed* the sateen cycle. The resulting of peculiarly pleasing texture. disphg7 ing comparatively long stretches of parallel fibres, affording a smooth and silky texture.
On (we threads and five picks only two pat tensor regular mums are possible. These are irditaaital at A and B in Fig. 11. Variations are produced by increasing the number of threads or picks in each stitch; thus producing patterns C and D in the same figure. Further variations give patterns F., F and G. It is readily seen that no regular sateen pattern can be worked out on six threads (each way). With seven threads, however, there are four; expressible by the leaps in the stitches, thus: 2-and-5. 3-and-4, 4-and-3, and 5-and-2. In an eight-thread design there can be only two shall be exposed in more or less solid masses. This form of weaving is employed more gen erally in textiles of cotton, linos and ak though sometimes in woolen dress goods. Well-known examples are table linen and up holstery. The stitch is usually of five-thread or eight-thread sateen. in some of the finer napery the ground work is in five-thread sateen and the figure in eight-thread sateen. 'These fine fabrics may show up to 140 threads of warp and 200 picks of weft to the square inch. An illustration of damask texture is shown in Fig. 12.
The possibility of combining the fundamen tal weaves in the production of •combination weave° textures has been referred to already The necessary limits of an article such as this preclude a discussioin of these numberless varia tions, and the student must be referred to the technical works cited in the bibliography at the close of the article.
Jacquard Loom.— A most important im rovement was made on the handloom by Joseph Jacquard of Lyons, who. in 1801, invented an apparatus by which the most intncate patterns could be woven as readily as plain cloth. This is accomplished by an ingenious arrangement of hooks and wires, by means of which the warp threads are lifted in any order necessary to make the shedding required by the pattern. The order in which these hooks and wires are suc beam" which operates the heddles. The hooks which remain on the pins of the knife beam lift the warp threads to which they are attached to the "roof" of the shed. The unhooked threads remain on its Moor." The operation will be more readily understood by referring to Fig. 13. When the pattern is extensive the machine may be provided with as many as 1,000 wires.