Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/491

Rh WEAVING 465 and irregular pattern a large number of different sheds of warp must be provided, and to secure with promptitude and certainty such manifold and complicated sheddings many of the most elegant and ingenious devices ever applied to mechanism have been in vented. Before invention culminated in the Jacquard apparatus the draw loom or draw-boy loom was the machine employed for making figured patterns such as damasks. In it each separate heddle shaft was fastened to a cord, which passed over a pulley, and coming down by the side of the loom these cords were arranged in a board in the order in which the heddles required to be drawn. The drawing of the cords and consequent formation of the shed was originally the work of a boy assistant, whence the name- draw-boy loom ; but it was found possible, by various mechanical attachments worked from the treadles, to dispense with extra aid to the weaver. But even with this arrangement the number of heddles which can be hung in any loom is limited, though, by using thin shafts and arranging them in tiers, as many as eighty or ninety may be ac commodated. Since as many as a thousand separate sheds may be required to form a complete pattern, a device other than shafts or leaves of heddles becomes necessary ; and the solution of the diffi culty is found in hanging the individual heddle mails, not in shafts, but independently, each with a small lead weight called a lingo attached to it. Thus in effect a separate heddle is provided for each thread of warp, and it becomes possible to effect any com bination of shed by cording together such leashes or mails as carry the warp threads to be raised. This tying together of the separate leashes, called &quot;tying the harness &quot; in the case of elaborate designs, is a tedious and difficult operation, requiring the exercise of con siderable skill and patience. The successive sheds of a pattern being tied up, it is only necessary to have the cords arranged in the order in which they are to be drawn and attached to the mechanical device for pulling them, and forming the sheds in proper succession. The Jacquard Loom. The Jacquard apparatus is the most important and ingenious appliance which has ever been adapted to weaving, since by its agency it has become possible to produce the most intricate and extended patterns with the same certainty and with almost as much rapidity as plain cloth. The credit of introducing and making the machine a practical success if not the whole honour of the invention is due to Joseph Marie Jacquard of Lyons (see vol. xiii. p. 539). Attention was first directed to this ingenious artisan by a model of a net- making machine invented by him, which was deposited in the Conservatoire des Arts et Metiers. He was requested in 1801 by Napoleon to examine and improve on a com plicated loom, and thereupon he undertook to produce a simple appliance to supplant the involved mechanism. The germs of the idea which he perfected had been, early in the eighteenth century, conceived by Bouchon and Falcon, and in 1745 it was further developed and im proved by Jacques deVaucan- son. Indeed, had Vaucanson been acquainted with the fly shuttle which was then known and used at least in England, it is probable he would have come to be re garded as the real inventor at once of the power-loom and of the apparatus which bears Jacquard s name. The fundamental principle of the Jacquard apparatus is simple, although in its working fine mechanical details are essential. Its object is to effect the raising of any number of separate leashes, corded leashes, or heddles, in any order and succession without special tying of harness. How the apparatus works will be made A plain by the diagram, fig. 7. Here A, A represent the separate leashes through which the warp U threads are drafted. It will bo FlG - &quot;-Diagram of Jacquard Loom, observed that these leashes are tied in pairs, but they might equally well be single, many together, or shafts of heddles. The cord from each separate leash passes through a finely perforated board B, called the comber-board, between which and C, the bottom board, the pairs are tied to a cord. These cords pass up through the bottoin board, and are caught in the lower hooks of a range of double-hooked long wires I), D. These hooked wires are supported and kept in position by being passed through loops or eyes in a range of cross-wires E, E. The head of each cross- wire is formed into an oblong eye as at a (an enlarged representa tion of a single cross-wire), through which a pin is passed for securing it in the spring-box F, in which each separate cross-wire presses against a small helical spring. The oblong eye permits a certain amount of play in the cross-wire, so that it can be pressed back against the helical spring when a force is applied at the opposite end. The points of the cross-wires pass through a perfor ated board G-, called the needle-board, projecting about a quarter of an inch beyond its outer surface. The upper hooks of the up right wires threaded through these cross-wires are attached to a board H, called the griffe. The whole function of the apparatus is to liberate these hooks in the order and to the extent necessary for the successive sheds. The hooks are dislocated thus. At the side of the projecting points of the cross-wires there is a quadrangular frame I, called the cylinder. This cylinder can be drawn back, and turned so that each face may in succession be presented to and pressed against the face from which the cross-wires protrude. The cylinder alone does not affect the wires, but its function is to carry on its rotating faces a succession of pasteboard cards which are punctured with holes in a definite order. The wires connected with hooks which are not to be disturbed pass through the punctured holes and remain unaffected, while those supporting the hooks to be displaced are pressed back by the cardboard surface, and this motion of the cross-wire lifts the hook of the upright wire off the griffe. The griffe now rises, carrying with it the undis turbed hooks, making a shed of the warp threads attached to their cords. The weft is then shot, the griffe descends, and the next punctured card is by a quarter revolution of the cylinder brought into contact with the cross-wires, and so the work goes on, succes sive Jacquard cards being presented, new combinations of shed effected, and the weft shot till the pattern is completed. Hooks to any desired number may be arranged in a Jacquard apparatus, and when a separate hook is applied to each individual leash the most complete control and variety of shed may be secured. But in practice this is not necessary. Each repeat of a pattern across a web may be corded up to one series of hooks, and in many ways it is practicable to limit the number of hooks required in weaving and thus to simplify the apparatus itself, and the system of punc tured cards by which its operation is governed. If the Jacquard apparatus, for example, is controlling only a few leaves of heddles, then only a corresponding number of hooks are called into use. Usually the machines are provided with 300, 400, 600, 900, and sometimes more hooks, and when intricate and extensive patterns are being woven two or more machines may be simultaneously brought to bear on the same loom. The Power-Loom. The first loom in which all the motions in weaving were connected and controlled by one motive power was the ribbon loom, known also as the Dutch or Dutch engine loom. A machine in which four to six pieces could be woven simultaneously is recorded to have been in existence in Dantzic in the last quarter of the sixteenth century (see RIBBONS, vol. xx. p. 531). In 1745 John Kay, inventor of the fly shuttle, and Joseph Stell patented improvements on the Dutch engine loom, which they said &quot; may go or be worked by hands, water, or any other force.&quot; The ribbon loom may be regarded as a series of distinct looms mounted, within one frame, each having its own warp and cloth beams, heddles, and shuttle, but all worked by one set of treadles and with a single batten. The shuttles are thrown across the narrow web by a rack-and-piniori arrangement ; they are simultane ously shot, and each occupies the place of its next neigh bour to the right or left alternately. The Jacquard appar atus and the drop-box arrangement for changing shuttles with change of weft are applied to the ribbon loom. The application of power to the weaving of ordinary webs has developed along a different line, and the common power-loom has nothing to do with the ribbon loom. So early as 1678 there was figured and described in the French Journal des Sfavans a machine &quot; for making linen cloth without the aid of a workman,&quot; the invention of De Gennes, a French naval officer. The loom made in 1745 by Vaucanson, which also foreshadowed the Jacquard apparatus, embodied many improvements on the XXIV. -- 59