Page:The American Cyclopædia (1879) Volume XVI.djvu/544

 WEAVING was inconvenient and wasteful of time, until Robert Kay, son of the inventor of the fly shut- tle, contrived the drop box ; in this, two, three, or more boxes, one over the other, at each side of the shuttle race, are so connected by a cord on which is a convenient handle, that, by moving this, one is made to slide down and the other up the swords of the batten ; the boxes at one side have in them each a shuttle with one color of thread, and by moving them any required one is brought at once to the level of the shut- tle race, so that its shuttle shall be next acted on by the picking peg and cord ; and in this way the colors and stripes are changed at the will of the workman, or in power looms by some device changing the boxes at the proper intervals. In the Jacquard apparatus, which can be attached to almost any kind of loom, a hollow prismatic box, extending the width of the fabric, has each of its sides perforated, in the direction of its length, with a number of straight rows of holes, corresponding, as each face is presented to the fabric, accurately with the points of as many rows of metallic bars, called needles. Each of these needles is pressed toward the box by a spiral spring, and each has passing through a loop in its length a lift- ing hook, which takes up, when lifted, its proper thread of the warp. These rows of lifting hooks terminate above also in hooks; and an arrangement of lifting bars is let down after each throw of the shuttle, to engage these upper hooka, raise the lifting hooks, and with thorn the warp threads. The prismatic box has also a reciprocating movement, by which at the same moments its sides are brought up to the ends of the needles ; and it turns to present a new face at each movement. If all the needles enter the holes of the box, all the lift- ing hooks are in position, and are engaged by the lifting bars as they descend, and all the warp threads are raised. But the weaving of complicated figures, such as those of carpets, tapestries, or shawls, requires that, through a certain cycle of movements of the shuttle, new groups of the warp threads continually shall be elevated. To determine, then, the groups of threads that shall be elevated, a succession of stiff cards looped together to form an end- less chain of any required length, and all of size and form corresponding to those of a side of the perforated box, are made to move suc- cessively over the box, one lying flat upon it at each of its movements. Now, the order and groups of threads raised are simply determined by perforating these cards beforehand, and in succession, with groups of holes that shall pre- cisely correspond only with the threads to be lifted for that part of the pattern. When the box now advances upon the needles, those meeting the unperforated portions of the card are forced back, their lifting rods are moved out of position, and only the threads answering to the needles that enter the holes are raised. With the use of this apparatus, it is only neces- sary further to arrange properly the succession of colors to appear in the weft, or in both warp and weft. Some improvements of the appa- ratus for particular uses have been made by English manufacturers. (See JACQUARD.) Not quite two centuries have passed since the origination of the first power loom, by M. de Gennes, a French naval officer of some dis- tinction, who communicated his plan to the French academy of sciences in 1678. The ad- vantages of productiveness, economy, unifor- mity of product, and convenience of weaving broad fabrics, which he claimed, are those practically realized and most important at the present day; but his loom was not brought into use. His account was translated in the same year for the " Philosophical Transac- tions;" and during a century or more several English inventors brought out power looms, none of which were generally adopted. The first successful power loom was the invention of the Rev. Edmund Cartwright (1784-'5). A principal cause which long delayed the adop- tion of these looms was the necessity for stop- ping the machine frequently, to dress the warp as unrolled from the beam; the employment for this purpose of a man for each loom pre- vented any saving of expense. In 1802 Mr. Radcliffe and Thomas Johnson, of Stockport, England, obviated this difficulty by producing the dressing machine in use in modern facto- ries, by which the dressing of the warp is com- pleted before it goes into the loom, being, du- ring one operation, sized, brushed, dried, and distributed on the warp beam. Later, Messrs. Horrocks and Marsland, also of Stockport, fur- ther completed the adaptation of the looms for being driven by steam; and Mr. Roberts, of Manchester, brought the working parts of the looms to nearly their present perfection. The frame of the power loom is of cast iron, and of great strength. The breast beam and cloth beam are situated much as in the hand loom. The warp beam, at the back of the loom, is at the level of the breast beam, and is kept back by a weight, while above and parallel with it, at the level of the cloth beam, is a roller over which the warp threads are passed, so as to lie on the loom in a horizontal direction. The heddles, for broad or heavy cloths, are so sus- pended by levers and cords that the depressing of one raises the other ; for light goods, a pair of rollers with cords suffices. To work the heddles, there are on a shaft running trans- versely across the loom two eccentric wheels on tappets differently set, the rims of which run on friction rollers fixed on levers of the third kind, pivoted at one end to the frame, while the movable end of each connects with one of the heddles. When the longer radius of either eccentric is down, the shorter of the other is so, and the lever and heddle corre- sponding to the former are depressed. Into the shed of the warp thus formed the shuttle is thrown by a sharp jerk communicated to it alternately from either side, by means of a single whip lever at the centre of the loom,