aermaucil-lzers/ Roving-machbfes.—The fly-frames shown in Figures 4 and 5 will serve as representatives of roving-frames for permanent twist. Here the stretched ribbon is carried by the front cylinders to the central aperture of a fork-like fly revolving at great speed. It then passes through a hollow arm of the fly to a wooden bobbin placed inside, upon the axis or spindle of the fly. This bobbin revolves independently at a sufficient rate of speed to wrap up in regular windings the length of thread furnished by the drawing-frame. Thus it will be seen that between the drawing frame and the fly a permanent twist and the requisite degree of solidity are imparted to the thread, the regular winding to a bobbin being effected at the same time. Each flying-frame contains a large number of spindles (from forty to one hundred) with flies and bobbins arranged in two rows, so that an equal number of rovings can be simultaneously made.
Spinning-machines.—The last step in the production of yarns is fine the vovings being sufficiently drawn out to attain the fineness required for the yarn. The thread now receives a permanent and suffi ciently sharp twist, which brings the fibres closely together and gives them a helical position; and filially the thread, whose length has now become considerable, must be wound up in a regular manner, so as sub sequently to allow of a ready unwinding. According as to whether these three operations are carried on simultaneously or alternately, two kinds of fine-spinning machines are distinguished in the manufacture of cotton yarns—namely, the water-frame and the mule-jenny.
IValer-frame.—The arrangement of the water-frame very much resem bles that of the fly-frame (figs. 4, 5), containing, like it, a drawing-frame, a fly effecting the twist for each thread, and a wooden bobbin (figs. 6, 7) for the reception of the yarn. While in the fly-frame, however, the bob bins are made to revolve by distinct mechanical movements adapted to the tender condition of the rovings, in the water-frame the bobbin is made to revolve by the pull of the yarn, which is kept sufficiently stretched by the weight of the bobbin and its friction upon the copping-rail. It will be seen from this arrangement that the yarn, to prevent its frequent break ing-, must possess a certain degree of firmness, and this is imparted to it by sharper twisting.
for soft yarns, snch as are used in the production of many woven articles, and which require a slighter twist, the water frame is not available and is replaced by the mule-jenny, shown in various arrangements in Figure 9 (pi. 37) and Figures i and 2 (pl. 38). Though
the stretching and twisting of the thread are simultaneously effected by this machine, the winding up is done intermittently each time after the completion of a certain length of thread (about 6 feet), the actual spinning being interrupted in the mean while. The yarn is not wound on wooden bobbins such as are shown in Figures 6 and 7 (pi. 37), but on slender con ical iron or steel spindles whose shape is represented in Figure 8.
There is a remarkable difference between the mule used for the pro duction of smooth yarn from cotton, long sheep's wool (worsted), etc., and that for rough carded yarns from short wool. In the first, where there is already a roving of great uniformity, the stretching is effected by means of an ordinary drawing-frame, but in the latter between a pair of feeding rollers and the spindle which serves for twisting as well as for winding, and which continues to recede from the feeding-rollers after the latter have come to a stand-still. The spindles, on whose periphery the thread is fastened, stand slightly inclined toward the vertical and revolve at great speed during the entire spinning process, thus imparting a permanent twist to the thread. If, now, the twisting and drawing be effected at the same time, as by the mule for carded wool, the twists affect the threads first upon the thin places, which oppose the least resistance to the twisting, whereby they obtain such a solidity that in the drawing they oppose a greater resistance than the remaining thicker but less twisted places, the drawing thus chiefly affecting the latter. The equalizing required on account of the uneven thickness of the rovings is in the process of fine spinning thus attained at the same time. This also explains the somewhat different arrangement of the mechanism of the mule for carded wool.
large number of threads (from two hundred to one thousand) are produced by a mule at the same time. A number of spindles corresponding to the number of threads to be spun stand in a row on a carriage, which runs on iron rails, alternately receding from and approaching the drawing-frame during the spinning and winding periods respectively. With the so-called "hand-mules" the motion of the car riage as well as the rotation of the spindles and the distribution of the windings on the spindle by a workman takes place during the latter period, while with the self-acting mules, which are chiefly used, all motions, with out exception, are derived from the driving-shaft. Figure 9 (p/. 37) and Figures 3 and 5 (pl. 38) show the external appearance of different self acting mules.