Page:The American Cyclopædia (1879) Volume V.djvu/418

into a tin cylinder. Cards are of various degrees of fineness according to the quality of yarn required; and for fine spinning two machines are used, the one coarse, called a breaker, succeeded by another called a finishing card. But the finest work of this kind accomplished by machinery is done by the combing machine of Heilman, patented in France. With this the short fibres and all impurities are separated from the long-stapled cotton, and the most perfect wool is prepared suitable for the manufacture of the finest muslins and laces. The principle of drawing out the sliver and repeatedly doubling this to produce a uniform roving has already been explained. Various machines have been introduced for twisting this roving and winding it upon bobbins. The fly frame, which came into use in 1817, is one of the most ingenious and efficient, and has taken the place of the old roving machine of Arkwright. In this frame spindles are set vertically in one or two rows at equal distances apart, each passing through a bobbin which is loosely attached to it, and has a play equal to its length up and down the spindle. At the top of the spindle is suspended a fly with two dependent legs, one of which is solid, and merely a counterpoise to the other, which is hollow, and admits through it the roving, which enters the fly by an eye in the centre, immediately above the top of the spindle. As the spindle revolves it carries the fly with it, thus twisting and winding the roving at the same time around the bobbin. The supply by the rollers is exactly proportioned to the speed of the spindles, which is uniform, and thus the twist is even in equal lengths; but as the fly winds the roving around the bobbin, and this consequently increases in circumference, the loosely twisted yarn would be more and more strained in the winding, were it not for ingenious contrivances which give a varying revolution to the bobbin exactly adapted to the circumference it has attained. It has moreover an alternating motion up and down the spindle, by which the roving is wound upon it in perfectly even layers. This machine, in the perfect adaptation of its parts to each other, and the mathematical accuracy of its operations, furnishes a most instructive study in this department of mechanics. The rovings are next to be spun into yarn, and this is accomplished either by the mule jenny, already partially described, or by the throstle machine. This is similar to the bobbin and fly frame in principle. As the roving is unwound from the bobbins, it is again elongated by passing between three pairs of rollers which revolve at different velocities, and it then passes through an eye in the foot of another flyer, which carries it around another bobbin as it also twists it. This bobbin has no motion adjusted to that of the spindle, but revolves with some friction upon the spindle, being drawn round by the thread, as the pull becomes sufficient to overcome the friction. The revolutions of the spindle in some machines are 5,000 in a minute, and its production in a week is then estimated about 27 hanks of No. 32. In consequence of the uncertain strain in winding up on the bobbin, the yarns are more likely to break than when they are spun by the mule, and this machine has consequently proved best adapted for the finer qualities of yarn. On account of the extra attention it required, and the time lost in the interruption to the spinning, as the carriage was run back and the yarns spun in the drawing out were wound upon the cops, the throstle frame was regarded as the most economical for spinning the coarse qualities as low as No. 32; but the improved self-acting mule has proved so much more economical to attend that it is now advantageously employed for spinning even the coarser yarns. As long ago as 1792 yarns were spun with the mule in Manchester, of the fineness of 278 hanks to the pound of 840 yards each. It was sold to the muslin manufacturers of Glasgow at 20 guineas the pound. These hanks are prepared by the next process, called reeling. The cops from the mule, or the bobbins from the throstle frame, are set in a frame so that they can be wound off upon a large six-sided reel, extending along the top of the same frame. With a reel of the circumference of 1½ yard, 560 revolutions give the length of a hank. Many of these are wound along the length of the reel at the same time. When taken off they are weighed separately, and the weight of each designates the fineness of the yarn. The number expresses the number of hanks required to weigh a pound. The coarsest yarns weigh about half a pound to the hank; but the common qualities for coarse spinning run from 10 to 40 to the pound. The finest spinning seldom exceeds 300 hanks to the pound. No yarn finer than No. 350 was made in England previous to 1840. It has since been made as fine as No. 2,150, but even No. 600 is too delicate to be handled or to serve any useful purpose. The finer yarns are singed by being run through a gas flame; they are then passed over a brush, and run through a hole in a piece of brass just large enough to admit the yarn. Any knot or bulge stops the yarn, and the defect is immediately remedied. The hanks are made up into cubical bundles of 5 or 10 lbs., and pressed and tied, when they are ready for the loom or for being twisted into thread, properly so called. Of this there are several kinds, as sewing thread, lace thread, stocking thread, &c. They are all produced by doubling and twisting together two yarns or more, and by machines very similar to the throstle frame; the yarns as they are twisted are passed through water or a weak solution of starch, which gives more firmness and strength to the thread. For further data connected with this manufacture, see the articles Calico, Calendering, and Loom.—Cotton is distinguished from linen by the peculiar structure of its fibre when seen under a powerful microscope, the form being flattened, crooked, and