The draw frame contains several heads of rollers, each head composed of a pair of feeding rollers a a, and a pair of draw rollers b b ; the upper roller in each pair is covered with leather, or some other elastic substance, and the lower pair is formed of metal, and fluted. The ends of the slivers con tained in the cans c c are passed through the leader d, and brought under the rollers a a and b b. If, now, we suppose the rollers b b to travel four times ss fast as the feed rollers a a, or to have a draught of four, as it is termed, the slivers will be drawn out to four times their original length. The slivers are united by passing through a conical ring, and conducted by a pair of rollers ff, (which do not draw or extend the cotton,) into another can g ; and if we suppose four ends to be thus united, the sliver will be of the same thickness as the original sliver, but of four times the length. This operation being repeated through several other heads on the same frame, the fibres of the cotton are laid nearly parallel, the sliver becomes more uniform, and is then ready to be carried to the roving frame, in which, besides being reduced, it receives a slight degree of twist. Roving frames have been variously constructed, but the form most approved and in most general use at the present day is what is termed the spindle and flyer roving frame, represented by the annexed diagram. a a, bb, are draw rollers, between which the sliver is con ducted from the cam c, and reduced according to the draught of the rollers; dd is the flyer fixed upon the top of the spindle e, which is put in motion by a band passing over the wheel f. The rollers deliver the reduced sliver to the flyers on the top of the spindles, where it passes through an eye g, and thence proceeds down one of the legs of the flyer (which is made tubular for that purpose,) to the bobbin Is, placed loosely on the spindle c, and supported on the rail. The tube of the flyer running swiftly round the bobbin, lays the roving (which thus acquires a twist) on the bobbin as fast as the rollers deliver it ; and in order to cover the surface of the bobbin with regularity, the rail i is made to ascend and descend alternately with a slow motion. The bobbin, it will be observed, is dragged round by the flyers, and but for the friction of the surface on which it rests, would move as fast as the flyers; but in this case it would take up no roving, for the quantity taken up will depend upon the difference between the speed of the flyer and the bobbin. A slight degree of friction is then necessary to the bobbin a slow motion, but as the bobbin becomes full, the weight increases the friction, and consequently would retard the motion still further if it were only dragged round by the flyer ; and as it is requisite that the bobbin should always take up the same quantity of roving, its motion is regulated so as to take up the roving exactly as fast as it is delivered from the rollers. The mechanism by which this is accomplished varies in different mills; the following is one of the most approved methods. Two conical barrels are placed opposite each other, the large end of the one fronting the small end of the other. One of these barrels moving uniformly turns the other barrel, by means of an endless strap, which, by being shifted towards either extremity, varies the speed of the other barrel. The belt or strap remains equally tight in every part of the barrels, for the diameter of the one increases in exactly the same proportion as that of the other diminishes. From the second barrel motion is conveyed to pulleys k resting on the bearer or rail i, and having the spindles passing through the centre of each ; the bobbins rest on those pulleys, and are carried round with them. The rovings are next carried to the spinning frame. The spinning frame is similar in its operation to the roving frame, except that it has generally three sets of drawing rollers, and from the greater strength which the thread has acquired, no machinery is requisite to regulate its motion ; it is therefore dragged round by the flyers. The bobbins, when taken off the spindles filled with water twist for warps, are carried to be reeled. The reel is composed of six rails, in front of which the bobbins are ranged on pins, in a board extending the whole length of the reel. The dimensions of the reel are such as that it requires exactly I yard to go round it ; the thread from the bobbins, after passing between several wires, to give a proper degree of tension, is made fast to one of the rails, and the wheel set in motion. After eighty revolutions (one lay) a bell or click strikes, the reel is stopped, and the lays are tied with pieces of thread to keep them distinct. Seven lays form a When the banks are completed they are taken off the reel, for which purpose one of the rails'is hinged, which permits it to be folded inward, and the hank being elided to one end of the reel, the reel is lifted off its bearing, and the banks are taken off.
It now remains to describe the ope ration of mule spinning. The preparation is similar to that of water spinning; but previously to the rovings receiving their Fast reduction on the spinning frame, they undergo a process called stretching.
The stretching frame nearly resembling the mule, except in being of larger dimensions: we shall proceed to de scribe the latter, by means of the annexed diagram. a represents a roving placed in a frame behind the drawing rollers c d e. After passing between the rollers, the reduced roving goes on to the spindle f, which are like those of the common jenny, and have neither bobbins nor flyers. The spindles are placed in a reclining position, and supported on a carriage g. The machine being put in motion, the carriage recedes as fast as the rollers deliver the rovings, the spindles at the same time revolving rapidly, giving sufficient twist to the yard to bear stretching. After the rollers have delivered a certain length (a yard, for example,) of yarn thus imperfectly twisted, they stop, but the carriage continues to recede half a yard further, for example, and the spindles continue to revolve. The yarn is thus stretched, and forms a fair and even thread. In order to save time, the spindles move more rapidly during the process of stretching. The mechanism by which this is effected is called double speed. The yarn being sufficiently hard twisted, the machine disengages itself from the other moving parts of the mule ; the attendant then returns the carriage home to the rollers. By this arrangement, comprising the advantages both of the rollers and the spindles, the thread is stretched more gently and equally, and a much finer quality of yarn can therefore be produced. This excellent machine, which has superseded the jenny, and, to a considerable extent, the water frame, and which has carried the cotton manufacture to a perfection it could not otherwise have attained, was invented by Samuel Crompton, a young weaver of respectable character and moderate circumstances, living at Hall-in-the-Wood, near Bolton, and was completed by him in 1779. Being of a retiring and unambitious disposition he took out no patent, and only regretted that public curiosity would not allow him " to enjoy his little invention to himself in his garret," and to earn by his own manual labour, undisturbed, the fruits of his ingenuity and perseverance. The very superior quality of his
yarn, it is said, drew persons from all quarters, to ascertain the manner whereby he produced it. He stated to Mr. Bannatyne, that, on the invention of his machine, he obtained 14s. per lb. for the spinning and preparation of No. 40, (i. e. yarn of forty hanks to the pound); that a short time after he got 25s. per lb. for the spinning and preparation of No. 60 ; and that he then spun a small quantity of No. 80, to show that it was not impossible, as was supposed, to spin yarn of so fine a grist, and for the spinning and preparation of this he got 42s. per lb. ! These prices were obtained by the unrivalled excellence of the yarn ; and it affords a criterion to estimate the value of the machine, when it is found that the price of yarn, No. 100, is at the present day only from 23. 3d. to 3s. per lb., including the cost of the raw material, which is from 10d. to ls. per lb., this surprising reduction having been effected chiefly by the powers of the mule; and notwithstanding it was before supposed to be impossible to spin 80 hanks- to the pound, as many as 350 hanks to the pound have since been spun, each hank measuring 840 yards, and forming together a thread 167 miles in length! Although the principle of Crompton's machine was excellent, it was rudely constructed; his rollers were of wood, and all the parts clumsy ; for Crompton was unused to tools, and knew but little of mechanics before he attempted to put to practice the beautiful combinations he had conceived. His first machine contained but 20 or 30 spindles. Subsequently, Stones, of Harwich, a machinist, constructed a mule in a workmanlike manner, making the rollers of metal, and applying clock-work to move them; the mule was thus adapted for 100 to 130 spindles. Baker, of Bury, and Hargraves, of Toddington, introduced some improvements. In 1790, Mr. Kelly, of Lanark mills, applied water power to the mule, and shortly after Mr. Wright, of Manchester, con structed a double mule. By these successive additions the machine was made capable of working with no less than 400 spindles. Since this period mules have been so much increased in size and effectiveness, that there are many at work in Manchester and elsewhere of 800 spindles each, and some of the prodigious number of 1100 spindles each, or 2200 the pair, the pair being managed by one spinner. Mr. Crompton having made no attempt to secure this important invention, Parliament was memorialized on the subject, and a grant of 50001. was obtained free of all charges ; and it is worthy of remark, that at this time (1812), there were at work, on the principle of his invention, between four and five millions of spindles! But the course of improvement has not yet stopped ; mules are now constructed which du not require the aid of a spinner, the mechanism being so contrived as to roll the spindle carriage out and in at the proper speed, without a hand touching it; and the only manual labour employed in these machines, (which are called self-acting mules,) is that of the children who join the broken threads. The first machine of this nature was invented by the ingenious Mr. W. Strutt, of Derby; son of Mr. dedediah Strutt, the partner of Ark wright. This appears to have been in the year 1790; and two years afterwards, Mr. Kelly, of Lanark mills, invented another self-acting mule, which is thus described by him in a letter to Mr. Kennedy, which we annex, as it furnishes a very interesting detail of the progress of improvement. " I first applied water power to the common mules in the year 1790 ; that is, we drove the mules by water, but put them up (that is, the carriage or spindle frame) in the common way, by applying the hand to the fly-wheel, and by placing the wheels (or mules) right and left; the spinner was thereby enabled to spin two mules in place of one The mules at that time were generally driven with ropes, made with cotton mill-waste, from a lying shaft in the middle of the room, and over gallows-pulleys above the fly-wheels, on each side of the room. That mode of driving was succeeded by belts, which were in every respect much better, and better adapted to self-acting mules, &c. From the above date I constantly had in view the self-acting mule, and trying to bring it into use ; and having got it to do very well for coarse numbers, I took out the patent in the summer of 1792. The object then was to spin with young people, like the water twist. For that purpose it was necessary that the carriage should be put up without the necessity of applying the hand to the fly-wheel. At first we used them completely self-acting in all the motions, the fly continui, to revolve, and after receiving the full quantity of twist, the spindles st... the guide or faller was turned down on the inside of the spindles, and the points were cleared of the thread at the same instant, by the rising of a guide, or inside faller (if it might be so called). When the outside guide wire, or faller, was moved round, or turned down to a certain point on the inside of the spindles, it then disengaged, or rather allowed a pulley, driven from the back of the belt-pulley, to come into geer, or action, and which gave motion to the spindles, and took in the carriages at the same time (similar to the way you assist the large mules in putting up). But in the above self-acting mule, which performed every motion, after the spindles were stopped it required about three turns of the fly-wheel to move round the faller, and put in action the above-mentioned pulley that took in the carriage, which was a great loss of time. We therefore set aside that part of the apparatus or machinery, and allowed the mule to stop in the common way, on receiving the full complement of twist; and the instant it stopped, the boy or girl, without putting their hand to the flywheel, just turned the guide or faller with the hand, which instantly set in motion the spindles, and took in the carriage, the cop being shaped by an inclined plane, or other contrivance It may naturally be asked, Why were not the self acting mules continued in use? At first, you know, the mules were about 144 spindles in size, and when power was applied, the spinner worked two of such ; but the size of mules rapidly increased to 300 spindles and upwards, and two such wheels being considered a sufficient task for a man to manage, the idea of saving, by spinning with boys and girls, was thus superseded." So numerous and diversified have been the successive improvements in this important branch of art, that a very large volume might readily be filled with merely a selection of the more ingenious ; but our prescribed limits compel us to confine our present notice to the most successful, and we believe the most perfect mechanism for spinning hitherto brought into use, which is the self-acting mule, invented by Mr. Roberts, of the firm of Sharp and Roberts, of Manchester. The following description of the invention, extracted from the patentee's specification, we copy from the London Journal of Arts and Sciences, Vol. VIII. Second Series.