THREAD MANUFACTURE. The doubling and twisting of cotton or linen yarn into a compact thread, for weaving bobbin-net, or for sewing garments, is performed by a machine resembling the throstle of the cotton-spinner. [Fig. 1138.] shows the thread-frame in a transverse section, perpendicular to its length. a, is the strong framing of cast iron; b, is the creel, or shelf, in which the bobbins of yarn l, l, are set loosely upon their respective skewers, along the whole line of the machine, their lower ends turning in oiled steps, and their upper in wire eyes; c, is a glass rod, across which the yarn runs as it is unwound; d, d, are oblong narrow troughs, lined with lead, and filled with water, for moistening the thread during its torsion; the threads being made to pass through eyes at the bottom of the fork e, which has an upright stem for lifting it out, without wetting the fingers, when any thing goes amiss; f, f, are the pressing rollers, the under one g, being of smooth iron, and the upper one h, of box-wood; the former extends from end to end of the frame, in lengths comprehending 18 threads, which are joined by square pieces, as in the drawing-rollers of the mule-jenny. The necks of the under rollers are supported, at the ends and the middle, by the standards i, secured to square bases j, both made of cast iron. The upper cylinder has an iron axis, and is formed of as many rollers as there are threads; each roller being kept in its place upon the lower one by the guides k, whose vertical slots receive the ends of the axes.
The yarn delivered by the bobbin l, glides over the rod c, and descends into the trough d, e, where it gets wetted; on emerging, it goes along the bottom of the roller g, turns up, so as to pass between it and h, then turns round the top of h, and finally proceeds obliquely downwards, to be wound upon the bobbin m, after traversing the guide-eye n. These guides are fixed to the end of a plate, which may be turned up by a hinge-joint at o, to make room for the bobbins to be changed.
There are three distinct simultaneous movements to be considered in this machine: 1. that of the rollers, or rather of the under roller, for the upper one revolves merely by friction; 2. that of the spindles m, s′; 3. the up-and-down motion of the bobbins upon the spindles.
The first of these motions is produced by means of toothed wheels, upon the right hand of the under set of rollers. The second motion, that of the spindles, is effected by the drum z, which extends the whole length of the frame, turning upon the shaft v, and communicating its rotatory movement (derived from the steam pulley) to the whorl b′, of the spindles, by means of the endless band or cord a′. Each of these cords turns four spindles, two upon each side of the frame. They are kept in a proper state of tension by the weights c′, which act tangentially upon the circular arc d′, fixed to the extremity of the bell-crank lever e′ f′ g′, and draw in a horizontal direction the tension pulleys h, embraced by the cords. The third movement, or the vertical traverse of the bobbins, along the spindles m, takes place as follows:—
The end of one of the under rollers carries a pinion, which takes into a carrier wheel, that communicates motion to a pinion upon the extremity of the shaft m′, of the heart-shaped pulley n′. As this eccentric revolves, it gives a reciprocating motion to the levers o′, o′, which oscillate in a vertical plane round the points, p′, p′. The extremities of these levers, on either side, act by means of the links q′, upon the arms of the sliding sockets r′, and cause the vertical rod s′, to slide up and down in guide-holes at t′, u′, along with the cast-iron step v′, which bears the bottom washer of the bobbins. The periphery of the heart-wheel n′, is seen to bear upon friction wheels x, x′, set in frames adjusted by screws upon the lower end of the bent levers, at such a distance from the point p′, as that the traverse of the bobbins may be equal to the length of their barrel.
By adapting change pinions and their corresponding wheels to the rollers, the delivery of the yarn may be increased or diminished in any degree, so as to vary the degree of twist put into it by the uniform rotation of the drum and spindles. The heart motion being derived from that of the rollers, will necessarily vary with it.
Silk thread is commonly twisted in lengths of from 50 to 100 feet, with hand reels, somewhat similar to those employed for making ropes by hand.
TILES. See [Bricks].