370

COTTON MANUFACTURE.

being loose upon the shaft, and actuated by the bevel pinions within, as described, ismade to revolve by the rotation of the wheel m, independent of the shaft, and with adifferent speed from the pulley box l; cords passing from this pulley bojc k, over guidesto small pulleys under the bobbins, communicate the motion, whatever it may be, of thepulley box Ic, to the bobbins, and cause them to turn, and to take up or wind tile yarnwith a speed derived from this source, independent of, and different from, the speed ofthe spindle and flier which twist the yarn.

It will now be perceived, that these parts being all adjusted to accommodate thefaking up movements to the twisting nr spinning of any particular quality of yarnintended to be produced, any variations between the velocities of the spinning andtaking up, which another quality of yarn may require, can easily be effected, by merelychanging the pinion v, for one with a different number of teeth, which will cause thewheel m, and the pulley box fc, to drive the bobbins faster or slower, as would be requiredin winding-on fine or coarse yarn, the speed of the twisting or spinning being thesame.

The rovings or spongy cords, of greater or less tenuity, made on the bobbin and fly,or tube roving frame, are either spun immediately into firm cohesive yarn, or receive afurther preparation process in the stretching frame, which is, in fact, merely a mule-jenny, without the second draught and second speed, and therefore need not be describedat present, as it will be in its place afterwards. ®

The finishing machines of a cotton mill, which spin the cohesive yarn, are of twoclasses; 1. the water-twist or throstle, in which the twisting and winding are performedsimultaneously upon progressive portions of the roving; and, 2. the mule, in which thethread is drawn out and stretched, with little twist, till a certain length of about 5 feetis extended, then the torsion is completed, and the finished thread is immediately woundupon the spindles into double conical coils called cops.

The water-twist frame, so called by its inventor, Sir R. Arkwright, because it was firstdriven by water, is now generally superseded by the throstle frame, in which the me-chanical spinning fingers, so to speak, are essentially the same, but the mode of commu-nicating the motion of the mill-gearing to them is somewhat different. Fig. 345 exhibitsa vertical section of the throstle. This machine is double, possessing upon each side ofits frame a row of spindles with all their subsidiary parts. The bobbins, filled withrovings from the bobbin and fly, or the tube frame, are set up in the creel a a, in tworanges, b, c, d, are the three usual pairs of drawing rollers, through which the yarj 1is attenuated to the proper degree of fineness, upon the principles already explained.At its escape from the front rollers, every thread runs through a guide eyelet e of wire,which gives it the vertical direction down towards the spindles J\ g. The spindles whichperform at once and uninterruptedly the twisting and winding-on of the thread deliveredby the rollers, are usually made of steel, and tempered at their lower ends. They standat g in steps, pass at v through a brass bush or collet which keeps them upright, anrevolve with remarkable speed upon their axes. The bobbins h, destined to take up th eyarn as it is spun, are stuck loosely upon the spindles, and rest independently of * ,ierotation of the spindles upon the copping beam l, with a leather washer between, Up° athe top of the spindles an iron-wire fork, called a fly or flier, i, k, is made fast by *left-hand screw, and has one of its forks turned round at the end into a little r*=jThe branch of the flier at / is tubular, to allow the thread to pass through, andescape by a little hole at its side, in order to reach the eyelet at the end of that/*From this eyelet i, it proceeds directly to the bobbin. By the twirling of the spin >the twisting of the portion of thread between the front roller d and the nozzle/effected. The winding-on takes place in the following way:—Since the bobbin hasother connexion with the spindle than that of the thread, it would, but for it, r6m t ] ieentirely motionless, relatively to the spindle. But the bobbin is pulled after it y erthread, so that it must follow the rotation of the spindle and fly. When we consthat the thread is pinched by the front roller d, and is thereby kept fully u * ,on n0 wstretch, we perceive that the rotation of the bobbin must be the result. Suppose ^ nethe tension to be suspended for an instant, while the rollers d deliver, for example, . ginch of yarn. The inertia or weight of the bobbin, and its friction upon thebeam l , by means of the leather washer, will, under this circumstance, cause the , - r jj n g10 hang back in a state of rest, till the said inch of yarn be wound on by the w j n gof the fly i, and the former tension be restored. The delivery of the yarn by the j nU _rollers, however, does not take place inch after inch, by starts, but at a certain c ^ ( j ieous rate; from whence results a continuous retardation or loitering, so to spea > ^ u p

bobbins behind the spindles, just to such an amount that the delivered yarn is vvat the same time during the rotation. bobbin

This process in spinning is essentially the same as what occurs in theand fly frame, but is here simplified, as the retardation regulates itselfthe diameter of the bobbin by the drag of the thread. In the fly frame the

accordin?

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