The traversing or warp threads are operated very differently. From the beams w, they are conducted through the eyelets x upward, through the plate N, thence through the slide-bars y, whence they pass upward, and are attached to the lace-beam G. The slide-bars y are perforated to receive the threads. There are 100 of these bars in a machine such as represented here, and the threads are concentrated in them in sets or stops, as required by the design, and it is from these that the designer measures the distance that the threads must be deflected or drawn aside by the action of the jacquard.
The lace-machine jacquard is specially constructed for the purpose, and differs in nearly all its details from that used in ordinary weaving. Each thread having to be moved through a known yet varying space, this is accomplished by using a series of wedges differing in size, which, being inserted between a sliding bar and a stud fixed upon each of the slides, is enabled by the movement of the bar to push the slide a distance corresponding to the size of the wedge which is adapted to the requirement of the pattern. The series of wedges consists of five : by the use of the first, the threads in the slides can be deflected over the space occupied by one bobbin in its carriage ; by the second, two such spaces can be traversed ; by the third, four ; by the fourth, eight ; the fifth being a repetition. The series thus stand in this order, 1, 2, 4, 8, 8; by the use of these, the warp threads can be deflected over any number of these "gates" from one to sixty-four.
The slide-bars (b, Fig. 888) are thin strips of fine steel, and contain holes for the passage through them of the warp threads. They are so thin that 100' do not occupy the space of an inch when set edgeways, the way they work, and yet allow space between them for the passage and deflection of the threads. The extremities away from the jacquard are attached to spiral springs, the opposite ones being connected with the slides of the jacquard, which move freely in sustaining guide-bars. Each bar at its extremity is furnished with a vertical projection or hook, which is for the purpose of preventing the spiral springs drawing them too far back after the action of the jacquard, the sustaining guide-bars arresting them at this point. Each bar also possesses two studs on its upper edge. Tho bars move simultaneously in opposite directions, according to requirement, and whilst in movement, have the wedges inserted between in such order as may he requisite; these are regulated by the action of the two series of cards T T', one being all the odd numbers, and the other the even. The jacquard possessing a double action enables the speed of every part to be accelerated in proportion, the pace being double that of the single action. The cylinders are worked
in the ordinary manner, and the wedges are fixed on the ends of thin flat springs, and have their lower ends made round in order to pass through the holes in the cards when required. The card cylinders are actuated by a reel log-shaft, which alternately raises and lowers them for the purpose of changing the cards. The cylinders, as they rise, raise the two series of wedges, unless the cards present perforations into which their lower extremities enter. The cards are numbered on their margins, showing the spaces over which the sliding-bars operated by them can be moved, and which figures indicate the wedges that are required to be raised by them, either singly or in combination. The cylinders and wedges have also a lateral movement in connection with the slide-bars, which is arranged in order to keep the wedges in position. The slides are shown in Fig. 888, fitted between the cross-bars E, which are actuated by cams fixed on the shaft driven by the gearing F. A pair of these bars are fitted to each side of the jacquard, and the slide-bars m are mounted upon the top. The spiral springs g are for the purpose of returning the slides to the first position, after the revolution of the cams. The compound jacquard has lately come into wide use ; it has a third set of eards for working the " thick " threads that outline the patterns. The cards of the jacquard are about 30 in. long by 2?, in. broad, and contain as many rows of holes as there are needles of the jacquard, with the addition of those required to form the selvages at each side of the lace web.
Each thread in a fabric of lace has a separate beam or bobbin ; and both are nicely regulated, so that the pace or delivery of the yarn shall not be greater than the requirement. The beams, of which there may be 100, or any other number according to the quantity of threads required to form the pattern, have a small pulley fixed upon one end, around which a cord is passed one or more times, accordiog to the amount of tension that may be needed, to the end of which a weight is attached, or it may be secured by a spring. The beams are tin tubes about in. in diameter, having small gudgeons at each extremity, on which they revolve. According to the number of times the pattern is repeated in a breadth of lace, or the number of separate breadths that may be produced at a time, will be the number of beams ; for, should it be a narrow edge or insertion lace which requires 100 warp threads, and there are say 60 breadths being woven, the corresponding threads in each pattern, requiring to be delivered alike in each instance, can be all put upon one beam, and thus the 6000 threads in 60 patterns may be aceommodated`upon 100 beams.