Page:The New International Encyclopædia 1st ed. v. 12.djvu/506

* LOOIII. 448 LOOM. out the warp. This loom is almost invariably supplied with the warpstop motion, already men- tioneil, and weavers are running sixteen to twenty of them on print-cloths, instead of eight of the common loom. Fio. 3. NOlri'iMioi' j,(M»M. Looms for fabrics which require not more than five harnesses to produce the weave are generally called cam-looms, for the reason that the harness is operated by the action of cams on the loom- treadles. For fabrics which require more than five harnesses, special fa}fci/-looms are arranged; these usually have a head-motion — a mechanism which regulates the pattern to be woven and may control the movement of as many as thirty har- nesses; dohhies and ivitches are special head-mo- tions. Looms for the weaving of figured patterns are fitted with the Jacrjziard machine, an appliance invented originally by .Joseph ]Iarie Jacquard (q.v. ), an ingenious Frenchman. He succeeded in producing a machine whereby an ordinary workman could with comparative ease produce the most beautiful patterns in a style which had previoiisly only been accomplished with great patience, skill, and labor. The machine. Fig. 4, may be applied to almost any style of loom and is simply a head-motion to control the loom-harness and to form the shed. It consists of a set of perpendicular hooks, AB, AB, connected with and controlled by a set of horizontal needles, C, C; above these hooks — which are placed in four, six, eight, or twelve rows to the machine, which may have from 200 to 1200 or more hooks — is a set of knives, T, T, called a qriffe, with one knife for each row of hooks. To the lower extremity of each hook is attached a loop of twine called the neck-cord, d, which is passed through the boltom-boaid. 2, 2, having perforations innnediately under each hook: from the neck-eords hang the leash- strings, E, E, and there may be from one to half a dozen of these to each hook. These leash-strings arc passed through a board placed hori- zontally a little above the warp to be woven, called the comber-hoard, 3, 3, having rows of per- forated holes to cor- resjiond with the number of warp threads. Thisboanl is divided into sec- tions, and in what is called a straiglit tie-up of the harness there are as many leash-strings to each hook as there are sections; in the il- lustration given there are four sec- tions. Below the comber- board and at tlic place where the shed is to be formeil each Icash-string is sup- plied with an eye called a tnail, F, F', through which the ,.^J^^ "" warp-thread to be controlled is passed ; and to the lower end of each leash- string is attached the lin(io, g, g', a small weiglit to draw it down. The neck-cord, leash-strings, mail, and lingos make up the Jacquard harn<'>---. The needles are held in place by a ncedle-hoanl. 4, 4, which is made with rows of holes tliroiigli which the ends of the needles pass about three- eighths of an inch, pointing to the front, and a spring-box, 5, 5, at the back having a series of spiral springs, one for each needle, which, press- ing the needle to the front, keep the hooks in a vertical position. The pattern to be woven is regulated by an endless chain Of heavy paste- board cards, L, L, L, which pass over a square prism, called the n/lilider. O P Q R, which is caused to revolve intermittently by swinging in and out like a pendiilnm in an arc. the cord of which is little longer than the cylinder is square; as the cylinder swings out the catch, x, engages one of the pins, 0, P, Q, R, causing the cylinder to make a quarter revolution, bringing a new card into position. The cylinder is perforated with rows of holes to correspond with the needles of the machine, and when the bare cylinder is allowed to come in contact with the needle-board, the needles projecting through the latter readily enter the perforations without moving the hooks; but the pattern-cards are so perforated that for all warp-threads that are to be raised above the filling in the woven pattern holes are cut for the needles which control them to pass through, the holes being cut to superimpose the holes in the cylinder; but holes are not cut in