M, two winglets, triple at bottom and single at top, placed likewise exteriorly, and which serve the same purposes as the preceding; m, are iron pins inserted in the cut-out beam G, which serve as stops or limits to the oscillations of the exterior winglets.
Now, if by any moving power (a man can drive a pair) rotation be impressed upon the large spindle No. 1., in the direction of the arrow, all the other spindles will necessarily pursue the rotatory movement indicated by the respective arrows. In this case, the 13 puppets working in the grooves of the heads of the spindles will be carried round simultaneously, and will proceed each in its turn, from one extremity of the machine to the opposite point, crossing those which have a retrograde movement. The 13 threads united at the point N, situated above the centre of the machine, will form at that point the braid, which after having passed over the pulley o, comes between the two rollers P Q, and is squeezed together, as in a flatting-mill, where the braid is calendered at the same time that it is delivered. It is obvious that the roller P, receives its motion from the toothed wheel of the spindle No. 3., and from the intermediate wheels R, S, T, as well as from the endless screw Z, which drives at proper speed the wheel W, fixed upon the shaft of the roller P.
The braid is denser in proportion as the point N is less elevated above the tops of the puppets; but in this case, the eccentric motion of these puppets is much more sensible in reference to that point, towards which all the threads converge, than when it is elevated. The threads which must be always kept equally stretched by means of a weight, as we shall presently see, are considerably strained by the traction, occasioned by the constantly eccentric movement of the puppets. From this cause, braiding machines must be worked at a moderate velocity. In general, for fine work, 30 turns of the large spindle per minute are the utmost that can safely be made.
The puppet or spindle of this machine, being the most important piece, I have represented it in section, upon a scale one fourth of its actual size, [fig. 158.] It is formed of a tube, a, of strong sheet iron well brazed; b is a disc, likewise of sheet iron, from which a narrow fillet, c, rises vertically as high as the tube, where both are pierced with holes, d e, through which the thread f is passed, as it comes from the bobbin, g, which turns freely upon the tube a. The top of this bobbin is conical and toothed. A small catch or detent, h, moveable in a vertical direction round i, falls by its own weight into the teeth of the crown of the bobbin, in which case this cannot revolve; but when the detent is raised so far as to disengage the teeth, and at the same time to pull the thread, the bobbin turns, and lets out thread till the detent falls back into these same teeth.
A skewer of iron wire, k, is loaded with a small weight, l, melted upon it. The top of this skewer has an eye in it, and the bottom is recurved as is shown in [fig. 158.], so that supposing the thread comes to break, this skewer falls into the actual position in the figure, where we see its lower end extending beyond the tube a, by about 1⁄4 of an inch; but as long as the thread is unbroken, the skewer k, which serves to keep it always tense, during the eccentric movement of the puppet, does not pass out below the tube.
This disposition has naturally furnished the means of causing the machine to stop, whenever one of the threads breaks. This inferior protrusion of the skewer pushes in its progress a detent, which instantly causes the band to slide from the driving pulley to the loose pulley. Thus the machine cannot operate unless all the threads be entire. It is the business of the operative, who has 3 or 4 under her charge, to mend the threads as they break, and to substitute full bobbins for empty ones, whenever the machine is stopped.
The braiding frame, though it does not move quickly, makes a great deal of noise, and would make still more, were the toothed wheels made of metal instead of wood. For them to act well, they should be made with the greatest precision, by means of appropriate tools for forming the teeth of the wheels, and the other peculiar parts.
BRAN. (Son, Fr.; Kleie, Germ.) The husky portion of ground wheat, separated by the boulter from the flour. It is advantageously employed by the calico printers, in the clearing process, in which, by boiling in bran-water, the colouring matters adhering to the non-mordanted parts of maddered goods, as well as the dun matters which cloud the mordanted portions, are removed. A valuable series of researches concerning the operation of bran in such cases was made a few years ago by that distinguished chemist and calico printer, M. Daniel Kœchlin-Schouch, and published in the ninth number of the Bulletin de la Société Industrielle de Mulhausen. Nine sets of experiments are recorded, which justified the following conclusions.