It was found that the process of spinning by rollers produced too great a strain upon the thread in its progress to admit of its being drawn as fine as is wanted for many purposes, and this led to the invention of the mule jenny by Cromp ton in 1779, which has a traveling frame upon which the spindles are set, and which in its mod em form is described below.
During the nineteenth century many important improvements were made in the details of the construction of spinning machinery, hut the gen eral principles are those worked out a hundred years ago. The greatest improvements have been changes in the construction of spindles, allow ing them to revolve more rapidly and freely. In the modern factory spinning is the final process in a series of operations necessary to convert the raw fibre into thread. Each of these pro cesses has for its object the removal of smaller and smaller impurities and the production of a finer and stronger thread. These are: (1) open ing and picking; (2) carding and combing; (3) drawing; (4) roving; (5) spinning. Other in termediate operations may be introduced.
The opener or breaker lapper is a similar ma chine to the intermediate or finisher tappers, as shown in Fig. 1, and described below. In the breaker lapper the cotton as taken from the bale cotton enters these machines in a sheet made up from the laps, A, delivered onto the slowly mov ing apron. from which it is taken by the feed rolls and delivered to the rapidly revolving beater. which forces it against the loosening the dirt and motes which fall through the grids into the The cotton is left in a light and feathery mass which is drawn be tween the by the suction of the fan, which also draws the dust and fine dirt from the beaten mass and discharges them through the The sheet of cotton from the squeeze rolls is taken by the and com pressed and finally rolled into the lap B. The lap is about one inch in thickness, 40 inches to 48 inches wide, and usually from 48 to 52 yards long.
After the cotton has passed through the series of lappers the laps from the finisher lapper go to the card (Fig. 2). (See CARDING.) The cot ton in the lap A is delivered to the of the card and is grasped by the teeth of the or from which it is taken in a thin sheet by the fine wire teeth of the on the cylinder B, and carried upward to come in contact with the teeth on the clothing of the and the fibres are combed into a degree of parallelism—the cylinder revolving rapidly, while the flats, which are in a chain, move slowly forward so that new flats are continually coming in contact with the cylinder— and much of the short and broken fibres is re moved: the comb, C. removes the short fibres
from the flats and they are rolled upon the rod, and the flats are further cleaned by the brush. The carded cotton is taken from the cylinder by the daffcr cylinder, the latter having a surface velocity somewhat less than that of the main cylinder, and is removed from the doffer by the described. The drawing sifter is carried through the trumpet and deposited in the can by the coiler the same as from the card. This drawing process is repeated two or three times as the work may de mand, always 'doubling' and 'drawing,' but with out putting in any twist. After the drawing comb, D, in a thin evenly carded film; this film is drawn through the trompet by the calender rolls, in a round strand about one inch thick called a slicer, which is automatically coiled in the Wirer-can by the coi/cr.
As all the processes are arranged to 'double' the mass of cotton and then to reduce the mass frames, the drawn sliver is placed in cans, behind the first of the roving frames which have rolls similar to the drawing frames. but have spindles by which the stock, then called rorinfL is twisted and wound on bobbins. The first of the roving frames is called the dubber, and is heavier than the intermediates and fine frames, as the other in size by 'drawing' it out to several times its original length until the yarn is finally produced, an examination of Fig. 3 will help the reader to understand how the 'drawing' acts on the fibres. On the left is shown the slicer from the card, the cotton being in a more or less tangled condition, but after passing between the successive pairs of drawcing•rolls, 4.4', the last or right hand pair, revolving faster than the others, 'draws' the fibres past each other and straightens them, bringing them into a nearly parallel position.