The movement of these faller wires into proper position, and the uncoiling of a small portion of yarn from each spindle, are both brought about by the "backing off" motion, which formed an important part of Roberts' Mule. It may be remarked, however, that certain of the predecessors of Roberts had made great efforts in this direction, thus making the way much easier for his applications, which were entirely successful. When "backing off" is completed, all the necessary parts are in position for winding the 64 inches of thread just given out upon each spindle.
This practically involves three primary and most important operations. (1) The drawing-in of the carriage back to its original position. (2) The revolution of the spindles at a speed suitable for winding the threads upon the spindles as the carriage moves inwards. (3) The guiding of the threads upon the spindles in such a manner that a cop of yarn will eventually be formed upon each spindle, of such dimensions and shape as to be quite suitable for any subsequent processes or handling.
Taking these three important divisions in the order given, it may be said that the drawing-in of the carriage is effected through the medium of the "scroll" bands, which are attached to the carriage at one end, and to certain spiral scrolls or fusees at the other end. The scrolls being revolved, wind the cords or bands round them, so pulling in the carriage. There are usually two back scroll bands and one front band, the latter being a sort of check band upon the action of the other two. What is termed the "rim band" revolves the spindles during the outward traverse of the carriage.
The drawing-in of the carriage in a sense causes the other two operations to be performed. With respect to the second of these, viz., revolving the spindles and thus winding the threads upon them, it may be said this action causes what is termed the "Winding Chain" to pull off a small drum of six inches diameter, thus rotating the latter and thereby the spindles. Here, however, comes in now the action of the very beautiful and effective piece of mechanism, "Roberts' quadrant" (see Fig. 26). The winding chain just mentioned is attached to one extremity to the arm of the quadrant, and the peculiar manner in which the quadrant moves in relation to the winding drum gives the variable motion to the spindles that is required.
When commencing a new set of cops it may take about eighty revolutions of the spindles to wind on the 64 inches of thread to each spindle, representing one stretch. The bare spindle may be about a quarter of an inch in diameter, but it may finally attain a diameter of an inch and a quarter (i.e., the cop upon the spindle). This cop will only require about twenty revolutions to wind on the 64 inches, which are only one-fourth of the revolutions necessary for the empty spindles. It is the action of the quadrant which gives this variation in speed to the spindles during winding-on.
But as has been pointed out previously, the quadrant imparts a "differential winding" motion to the spindles in two distinct and different ways, and the second motion is even more important than the first.
It is necessary for practical purposes that the cop of yarn should be built up of a conical shape in the upper part, as shown in the illustration. Now it must be obvious to the least technical of the readers of this story, that to wind a given portion of yarn upon the thin apex of a cone, will require a greater number of revolutions than would be necessary to wind the same length of yarn upon the base of the same cop. All the way between the apex and the base of the cone are also other varying diameters, and during each return movement of the mule carriage the thread is wound upon all the varying diameters of the cone in succession.
This implies the necessity for the revolutions of the spindles to a varying quantity all the time of the return or inward movement of the spindle carriage.
The quadrant gives this varying speed in a manner which is all but mathematically correct, any slight deviation from any such mathematical correctness being easily compensated for in other ways.
For the specific manner in which this quadrant works, the reader is referred to any of the recent text-books on cotton spinning.
The third primary and important operation, which takes place during each return movement of the carriage, is the guiding of the thread upon the spindles in a correct manner. This operation is closely associated, however, with the action of the quadrant.
That portion of a "self-actor mule" which guides the faller wires is termed the "shaper" or "copping motion." It consists of an inclined iron rail upon the upper smooth surface of which slides the "copping bowl," this being a portion of the mechanism which connects the rail with the faller wires. The rail rests upon suitable inclines termed "copping plates," whose duty it is to regulate the movement of the rail so as to allow for the ever-increasing dimensions of the cop during the building process. When the carriage again reaches its initial position, suitable mechanism causes all the parts to return in the position required for spinning.
Such is the complete cycle of movements of the "mule," each succeeding cycle being simply a repetition of the preceding. It will probably take such a mule as the one described about six hours to make a "set of cops," i.e., one on each spindle, each cop being 1¼ inches in diameter and 7½ inches long. Every fifteen seconds, while the mule is making a cycle of its movements, may be divided up approximately as follows: nine seconds for the drawing-out and twisting; two seconds for backing-off; four seconds for winding-on and resuming initial position.
A multitude of minor motions and details might be easily expanded into several chapters; in fact, more can be said about the mule than about any other spinning machine, but such detailed description would be out of place in this story.
All the motions just named are centred in what is termed the "Head Stock," this being placed midway in the length of the mule.
This head stock receives all the power to drive the various motions, from the shafting and gearing, and distributes it in a suitable manner to various parts of the machine.
It will have been observed by this time, that, as in the case of the bobbin and fly frames, the intricate and wonderful mechanism of the self-actor mule is not devoted to the formation of threads, but to the effective and economical placing of the threads of yarn, in the form of cops, after it has been spun.
The spinning processes take place during the outward traverse of the mule carriage, the mechanism involved in this motion being comparatively simple. The really complicated and difficult motions being "backing-off," revolving the spindles "during winding-on," and the guiding of the spun threads upon the spindles during the winding-on process. It was the addition of these three motions by the later inventors which gave the mule the title of "Self-Acting."
The Ring Spinning Machine.—In a former chapter it was shown how within the space of two decades the three rival spinning machines of Hargreaves, Arkwright and Crompton were introduced, also it was pointed out, that Crompton's machines contained the best points of both of his predecessors. The mule did not immediately become the sole spinning machine. From the outset there was a close contest between the continuous spinning machine of Arkwright and the intermittent spinning machine of Crompton. It was not long, however, before the mule asserted its superiority over the water frame for fine muslin yarns, and for weft yarns. Eventually the water frame was relegated to the production of strong warp yarns, and later still it has come to be largely utilised as a doubling machine. As a matter of fact, it is contended by experts of the present day, that no machine ever made a rounder and more solid thread than the water frame, or flyer-throstle, as it has been called in its improved form.
During the last thirty years, a revolution practically in cotton spinning has been gradually brought about, and even to-day active developments are to be seen. The continuous system of spinning, which for a time had to take a second place, now appears to be again forging ahead, and looks as though it would supersede its more ponderous rival. Especially in countries outside England is this the case, for it is found that the method of ring spinning preponderates, and even in England the number of spindles devoted to continuous spinning is constantly increasing.
This change has chiefly been brought about by what may be termed a revolution in the winding and twisting mechanism of the continuous spinning machine itself.
Arkwright's flyer and spindle, after improvement by subsequent inventors, could not be revolved at anything like the speed of the spindle of the mule, and, in addition to this, the yarn had to be wound always upon the bobbin, very much after the style of the bobbin and fly frames previously described.
Experiments, however, were repeatedly made in the direction of dispensing with the flyer altogether, and some thirty years ago these unique spinning frames had attained very general adoption in the United States of America, where the comparative dearth of skilled mule spinners had furnished an impetus to improvement of the simple machine of Arkwright.
About this time, the attention of certain English makers being directed to the success of the new spinning frames in America, led to their introduction into England. But little time elapsed before they received a fair amount of adoption, but for many years they had a restricted use, viz., for doubling, that is, the twisting of two or more spun threads together, to form a stronger finished thread.
In this way, they were, strictly speaking, rivals of the throstle doubling frame more than the spinning mule.
By and by, however, the time came when the new frames began to be adopted as spinning machines, and to-day there are many English and foreign mills containing nothing else in spinning machines on the continuous system except these. In not a few mills in different countries, both types are found running.
A careful glance at the picture of this rival of the mule, will help in the following description of it:—
The flyer which is to be seen on the old Saxony wheel, and which was perpetuated in the celebrated machine of Arkwright, is entirely dispensed with, and all its functions efficiently performed by apparatus, simple in itself; it is yet capable of high speed and heavy production.
First of all, there is a vastly improved and cleverly constructed form of spindle, by which, in the latest and best makes, any speed can be attained which is likely to be required for spinning purposes.
Perhaps the apparatus which plays the most important part in performing the duties of the displaced flyer, is a tiny "traveller" revolving round a specially made steel ring about 2 inches in diameter.
The use of these two latter gives the distinctive names of "Ring-spinning" to the new system and "Ring Frame" to the machine itself.
In describing this system of spinning the creel of rovings to be operated upon, and the drawing rollers being practically identical with machines already described, little here is required to be said of them, but there is, however, a modification in the arrangement of the rollers which is referred to later on.
After leaving the rollers, a thread of yarn is conducted downwards and passed through the "travellers," which may be seen in the illustration, and then attached to the bobbin. The "traveller" is a tiny ring made of finely tempered steel. It is sprung upon the edge of the ring shown in the frame, and which is specially shaped to receive the tiny ring or traveller referred to.
The bobbin in this case is practically fast to the spindle—unlike any other case in cotton-spinning machinery—and it is therefore carried round by the spindle at the same rate of speed.
As the spindle and bobbin revolve, they pull the traveller round by the yarn which passes through it, being connected at one end to the bobbin and the rollers above forming another point of attachment. If the reader will look carefully at the illustration he will see how twist is put in the yarn. The joint action, then, of bobbin, traveller and fixed ring, is to put the necessary twist in the yarn which gives it its proper degree of strength. If no fresh roving from the rollers were issuing for the moment, the small portion of thread reaching from the rollers to the bobbins would simply be twisted without any "winding-on" taking place. As a matter of fact, the roving always is issuing from the rollers, and "winding-on" of the twisted roving is performed by the traveller lagging behind the bobbin in speed, to a degree equal to the delivery of roving by the rollers. It will be remembered that in the old flyer-throstle "winding-on" was performed by the bobbin lagging behind the spindle, a procedure which is impossible on the ring frame.
There is also an arrangement of the mechanism for guiding and shaping the yarn upon the bobbins in suitable form, the action being as nearly as possible an imitation of the mule.
For a number of years after the introduction of these frames, it was found that the threads often broke down owing to the twist not extending through the roving to the point where it issued from the rollers. This was eventually remedied by placing the drawing rollers in a different position, thus causing the thread running from the rollers to the traveller to approach more to the vertical; this constituting the modification which has just been referred to previously.
Another difficulty was experienced in the fact that during spinning the threads would sometimes fly outwards to such an extent that adjacent threads came in contact with each other, causing excessive breakage. This was technically termed "ballooning," and has been very satisfactorily restricted by the invention of special apparatus.
At the present time, therefore, a contest between the two rival systems of continuous spinning which were in bitter antagonism over a century ago, is waging a more fiercely contested fight than at any previous time.
As the case stands to-day, the mule is retained for nearly all the best and finest yarns as yet found; the most suitable for them, just as it was when Crompton got 25s. per pound for spinning fine muslin yarns on his first mule.
In many cases, also, yarn is specially required to be spun upon the bare spindle as on a mule, as for instance when used as weft and put into the shuttle of a loom. It is probably the very greatest defect of the ring frame that it can only, with great difficulty, be made to form a good cop of yarn on the bare spindle, although thousands of pounds have been spent on experimenting in that direction. How soon it may be accomplished with commercial success cannot be known, as a great number of individuals are constantly working in that direction. If it does come about, there can be no doubt that the ring frame will receive a still further impetus.
Even now, for medium counts of yarn it is much more productive than the mule, owing to its being a continuous spinner. Another vast advantage that it possesses is the extreme simplicity of its parts and work as compared with the mule. Because of this, women and girls are invariably employed on the ring frames, whereas it requires skilled and well-paid workmen for the mules.
The Combing Machine.—As compared with the Scutcher, the Carding Engine and Mule, the Comber is a much more modern machine. Combing may be defined as being the most highly perfected application of the carding principle.
The chief objects aimed at by the comber are:—To extract all fibres below a certain length; to make the fibres parallel; and to extract any fine impurities that may have escaped the scutching and carding processes.
It is worthy of note that although nearly all the great inventions relating to cotton-spinning have been brought out by Englishmen, the combing machine is a notable exception. It was invented a few years prior to 1851 by Joshua Heilman, who was born at Mulhouse, the principal seat of the Alsace cotton manufacture, in 1796.
Like Samuel Crompton—the inventor of the mule—Joshua Heilman appears to have possessed the inventive faculty in a high degree, and he received an excellent training in mathematics, mechanical drawing, practical mechanics, and other subjects calculated to assist him in his career as an inventor.
Heilman was the inventor of several useful improvements in connection with spinning and weaving machinery, but the invention of the comber was undoubtedly his greatest achievement.
He was brought up in comparatively easy circumstances, and married a wife possessing a considerable amount of money; but all that both of them possessed was swallowed up by Heilman's expenses in connection with his inventions, and he himself was only raised from poverty again by the success of the comber shortly before his death, his wife having died in the midst of their poverty many years previously.
After Heilman became possessed of the idea of inventing a combing machine, he laboured incessantly at the project for several years, first in his native country and subsequently in England. The firm of Sharpe & Roberts, formerly so famous in connection with the self-actor mule, made him a model, which, however, did not perform what Heilman required.
Afterwards he returned again to his native Alsace still possessed with the idea, and finally it is said that the successful inspiration came to him whilst watching his daughters comb out their long hair. The ultimate result was that he invented a machine which was shown at the great exhibition of London in 1851 and immediately attracted the attention of the textile manufacturers of Lancashire and Yorkshire.
Large sums of money were paid him by certain of the Lancashire cotton spinners for its exclusive use in the cotton trade. Certain of the woollen masters of Yorkshire did the same, for its exclusive application to their trade, and it was also adopted for other textiles, although Heilman himself only lived a short time after his great success.
It must be understood that the comber is only used by a comparatively small proportion of the cotton spinners of the world. For all ordinary purposes a sufficiently good quality of yarn can be made without the comber, and no other machine in cotton spinning adds half as much as the comber to the expense of producing cotton yarn from the raw material.
To show this point with greater force, it may be mentioned that the comber may make about 17 per cent. of waste, which is approximately as much as all the other machines in the mill put together would make.
Its use, however, is indispensable in the production of the finest yarns, since no other machine can extract short fibre like the comber. It is seldom used for counts of yarn below 60's and often as fine yarns as 100's or more are made without the comber. In England its use is chiefly centred in the localities of Bolton, Manchester, and Bollington, although there is a little combing in Preston, Ashton under Lyne, and other places.
Perhaps its greatest value consists in the fact that its use enables fine yarns to be made out of cotton otherwise much too poor in quality for the work; this being rendered possible chiefly by the special virtue possessed by the comber of extracting all fibres of cotton below a certain length. This of course has led to the increased production and consequently reduced price of the better qualities of yarn.
Reverting now to the Heilman Comber as it stands to-day, an excellent idea of the machine as a whole will be gathered from the photograph in Fig. 31.
There are usually six small laps being operated upon simultaneously in one comber. Each small lap being from 7½ inches to 10½ inches wide, being placed on fluted wooden rollers behind the machine, is slowly unwound by frictional contact therewith, and the sheet of cotton thus unwound is passed down a highly polished convex guide-plate to a pair of small fluted steel rollers.
Both the wooden and the steel rollers have an intermittent motion, as indeed have also all the chief parts of the machine concerned in the actual combing of the cotton. The rollers, during each intermittent movement, may project forward about ⅜ of an inch length of thin cotton lap.
By this forward movement the cotton fibres are passed between a pair of nippers which has been for the instant opened on purpose to allow of this action. Immediately the cotton has passed between the nippers, the feed rollers stop for an instant and the jaws of the nippers shut and hold the longer of the cotton fibres in a very firm manner.
The shorter fibres, however, are not held so firmly, and are now combed away from the main body of the fibres by fine needles being passed through them. The needles are fixed in a revolving cylinder and are graduated in fineness and in closeness of setting, so that while the first rows of needles may be about 20 to the inch, the last rows may contain as many as 80 to the inch, there being from 15 to 17 rows of needles in an ordinary comber.
The short fibres being combed out by the needles are stripped therefrom, and passed by suitable mechanism to the back of the machine to be afterwards used in the production of lower counts of yarn.
The needles of the revolving cylinder having passed through the fibres, the nippers open again and at the same time another row of comb teeth or needles, termed the top comb, descends into the fibres. The fibres now being liberated, certain detaching and attaching mechanism; as it is termed, is brought into action, and the long fibres are taken forward, being pulled through the top comb during this operation. Thus the front ends of the fibres are first combed and immediately afterwards the back ends of the same fibres are combed. During the actual operation of combing each small portion of cotton, the latter is quite separated from the portion previously combed, and it is part of the work of the detaching and attaching mechanism to lay the newly combed portion upon that previously combed. From a mechanical point of view, the detaching and attaching mechanism is more difficult to understand than any other portion of the comber, and it is no part of the purpose of this "story of the Cotton plant" to enter into a description of this intricate mechanism.
Sufficient be it to say that the combed cotton leaves the detaching rollers in a thin silky-looking fleece which is at once gathered up into a round sliver or strand and conducted down a long guide-plate towards the end of the machine. This guide-plate is clearly shown in the photograph of the comber, where also it will be seen that the slivers from the six laps which have been operated upon simultaneously are now laid side by side.
In this form the cotton passes through the "draw-box" at the end of the comber, and being here reduced practically to the dimensions of one sliver it passes through a narrow funnel and is placed in a can in convenient form for the next process.
When the combing is adopted, it precedes the drawing frame, which has previously been described, and the cans of sliver from the comber are taken directly to the draw-frame.
For intricacy and multiplicity of parts of mechanism, the comber is second only in cotton-spinning machinery to the self-acting mule, and is probably less understood, since its use is confined to a section of the trade. The latest development is the duplex comber, which makes the extraordinarily large number of one hundred and twenty nips per minute, as compared with about eighty-five nips per minute for the modern single nip comber. All this is the result of improvement in detail, as the principle of Heilman's Comber remains the same as he left it. It ought to be added that other types of comber have been adopted on the continent with some show of success.
Sliver Lap Machine.—Combing succeeds carding and is practically a continuation of the carding principle to a much finer degree than is possible on the card. The Carding Engine, however, makes slivers or strands of cotton, while the comber requires the cotton to be presented to it in the form of thin sheets. It therefore becomes requisite to employ apparatus for converting a number of the card slivers into a narrow lap for the comber.
The machine universally employed is termed "The Sliver Lap Machine," or, in some cases, "The Derby Doubler," and a modern machine is shown in the photograph forming Fig. 32.
In this case, eighteen cans are placed behind the machines, and the sliver from each can is conducted through an aperture in the back guide-plate designed to prevent entanglements of sliver from passing forward. Next each sliver passes over a spoon lever forming part of a motion for automatically stopping the machine when an end breaks. The eighteen slivers now pass side by side through three pairs of drawing rollers with a slight draft, and between calender rollers to a wooden "core" or roller. Upon this roller the slivers are wound in the form of a lap, being assimilated to one another by the action of the drawing and calender rollers.
Special Drawing Frame.—In order to have the fibres of cotton in the best possible condition for obtaining the maximum efficiency out of the combing action, it is the common practice to employ a special drawing frame between the card and the sliver lap machine.
As described elsewhere in this little story, the use of the drawing frame is to make the fibres of cotton more parallel to each other by the drawing action of the rollers, and to produce uniformity in the slivers of cotton by doubling about six of them together and reducing the six down to the dimensions of one. In the case under discussion the slivers from the card are taken to the special drawing frame and treated by it, and then passed along to the sliver lap machine as just described.
Ribbon Machine.—Quite recently a machine has come slightly into use designed to supersede this special drawing frame. This new machine is termed the "Ribbon Lap Machine," and it may be described as a variation of the principle of the machine it is designed to supersede. The difference is this, that, whereas the drawing frame doubles and attenuates slivers of cotton, the Ribbon Machine operates upon small laps formed of ribbons or narrow sheets of cotton. By this treatment, the evening and parallelising benefits of the drawing frame are secured, with the addition of a third advantage, which may be briefly explained. The slivers, which in the sliver lap machine are laid side by side so as to form a lap, have a tendency to show an individuality so as to present a more or less thick and thin sheet to the action of the nippers of the comber. The latter, therefore, hold the cotton somewhat feebly at the thin places, thus allowing the needles of the revolving cylinder to comb out a portion of good cotton. When the Ribbon Lap Machine is employed, the slivers from the card are taken directly to the Sliver Lap Machine and the laps made by this machine are passed through the Ribbon Machine. Six laps being operated upon simultaneously by the rollers, are laid one upon another at the front so that thick and thin places amalgamate to produce a sheet of uniform thickness. The use of the Ribbon Machine is limited at present owing to its possessing certain disadvantages.
Having initiated our readers into all the processes incidental to the production of the long fine threads of yarn from the ponderous and weighty bales of cotton as received at the mill, it remains for us to briefly indicate the more common uses to which the spun yarn is applied.
A very large quantity of yarn is consumed in the weaving mills for the production of grey cloth without further treatment in the spinning mill, except that the cops of yarn are packed in ships, boxes, or casks, in convenient form for transit purposes.
If for weft, the cops are forthwith taken to the loom, ready for the shuttle.
If for warp, then the yarn passes through a number of processes necessary for its conversion, from the mule cop or ring bobbin form, into the sheet form, consisting of many hundreds of threads, which are then wound on a beam.
Briefly enumerated, these processes are as follows:—
(a) The winding frame, in which the threads from the cops or spools are wound upon flanged wooden bobbins, suitable for the creel of the next machine.
(b) The beam warping frame, in which perhaps 400 threads are pulled from the bobbins made at the winding frame, and wound side by side upon a large wooden beam.
(c) The "slasher sizing frame," in which the threads from perhaps five of the beams made at the warping machine are unwound and laid upon one another, so as to form a much denser warp of perhaps 2000 threads, and wrapped on a beam in a suitable form for fitting in the loom as the warp or "woof" of the woven fabric. In addition to this, the sizing machine contains mechanism by which the threads are made to pass through a mixing of "size" or paste, which strengthens the threads.
In some cases this "size" is laid on the yarn very thickly, in order to make the cloth weigh heavier.
(d) After sizing comes the subsidiary process of "drawing in" or "twisting in," by which all the threads are passed in a suitable manner through "healds" and "reeds," so as to allow of their proper manipulation by the mechanism of the loom, to which they are immediately afterwards transferred.
In the production of cloths of a more or less "fancy" description, it is often required that the spun yarns shall be bleached and dyed before using, and to perform one or both of these operations efficiently, it is usual to reduce the yarn into proper condition by the processes of "reeling" and "bundling," although in comparatively few instances yarn is dyed in the cop form, while in a few other cases the raw cotton is dyed before being subjected to the processes of cotton spinning.
"Reeling" and "Bundling" are operations which are frequently necessary for other purposes besides those above alluded to, and may therefore be more fully described, as they often form part of the equipment of a spinning mill, and yarn is frequently sent away from the spinning mill in bundle form.
Reeling.—This is a simple but very extensively adopted process, in which yarn is wound from cops, bobbins or spools into hanks. It may be explained here that a cotton hank consists of 840 yards, and is made up of 7 leas of 120 yards each, while on a reel each lea is made up of 80 threads, a thread being 54 inches and equalling the circumference of the reel. Perhaps the most common size of reel contains at one time 40 spindles, and is capable therefore of winding 40 hanks of yarn simultaneously. The photograph in Fig. 34 shows a number of reels fitted for winding hanks from cops formed upon the mule.
The cops being put on the skewers, the end of yarn from each is attached to the reel or "swift" ready for starting. These reels may be arranged so as to be operated from shafting by mechanical power, or by the hand of the attendants.
Reeling is performed by women, and in our photo the attendant is seen in the actual operation of reeling.
A hank of yarn having been taken from each cop, the reel is stopped and closed up so as to allow of the ready withdrawal of the hanks.
Bundling Machine.—The Bundling press is solely intended to assist in the making up of the hanks of yarn into a form suitable for ready and convenient transit. In order to exercise a sufficient pressure upon the yarn to make a compact bundle, it is necessary for the framing to be of a very strong character, as will be especially noticed in Fig. 35.
The bundles of yarn made up on the bundling machine are usually 5 to 10 pounds weight, the latter being by far the more common size. The bundle shown in the yarn-box of our illustration is 10 pounds in weight and is practically ready for removal.
Before placing the yarn in the machine, several hanks are twisted together to form a knot, and these "knots" comprise the individual members of the bundle shown in the illustration.
In the sides of the yarn-box there are four divisions, through which are threaded as many strings, upon which may be placed cardboard backs. Then the knots of yarn are neatly placed upon the strings, and the cardboard and the strong top bars of the press securely fastened down. Certain cams and levers are then set in motion, by which the yarn table is slowly and powerfully raised so as to press the yarn with great force against the top bars. A sufficient pressure having been exerted, the bundle is tied up and withdrawn from the press, only requiring to be neatly wrapped in stout paper to be quite ready for transit purposes.
Sewing Thread.—A very large quantity of spun yarn is subsequently made into sewing thread. It is a fact well known to practical men that we have no means in cotton spinning by which a thread can be spun directly of sufficient strength to be used as sewing thread. For instance, suppose we wanted a 12's sewing thread, i.e., a thread containing 12 hanks in one pound of yarn; it would be practically impossible to spin a thread sufficiently good to meet the requirements of the case. The method generally adopted is to spin a much finer yarn and to make the finished thread by doubling several of the fine spun yarns together in order to form the thicker final thread. For instance, to produce a 12's thread it is probable that 4 threads of single 48's would be doubled together, or say 4 threads of 50's, to allow for the slight contraction of the yarn brought about by twisting the single threads round one another.
In order to perform this doubling operation in an efficient manner for the production of thread, it is usual to employ two machines.
The first of these is shown in the illustration, and is termed the quick traverse winding machine. Here the cops from the mule, or the bobbins from the ring frame, are fitted in a suitable creel, as shown clearly at the front and lower part of our illustration. Each thread of yarn is conducted over a flannel-covered board which cleans the yarn and keeps it tight. Then each thread passes through the eye of a small detector wire which is held up by the thread and forms part of an automatic stop motion which stops the rotation of any particular bobbin or "cheese" when an end or thread belonging to that "cheese" fails or breaks, leaving the needles or detector wires. All the threads—from two to six in number—belonging to one "cheese" are combined to form one loose rope or thicker thread.
It ought to be explained that the term cheese is applied to the kind of bobbin of yarn which is formed upon this particular machine, one or two being placed as shown on the frame work.
Doubling Machine.—The machine just described does not put any twist into the thread, although twisting is a process which is absolutely indispensable for the proper combination of the several single threads so as to produce a strong doubled thread.
The twisting operation is therefore performed on the machine illustrated in Fig. 37, and termed the "Ring doubling machine."
In the creel of this machine are placed the cheeses formed on the winding machine, and the threads are conducted downward and usually under a glass rod in trough containing water, as the addition of water helps to solidify the single threads better into one doubled thread. From the water trough the threads are conducted between a pair of revolving brass rollers which draw the threads from the cheeses and pass them forward to the front of the machine. Here each doubled thread extends downwards and passes through a "traveller" upon the bobbin.
This machine is a modification of the ring spinning frame previously described and therefore does not call for detailed treatment at our hands.
The two machines are practically identical in principle, the chief difference being that in the doubler there are no drawing rollers, as the cotton is not attenuated in any degree at this stage.
Other differences consist in having larger "travellers" and "rings" and "spindles," and in a different kind of bobbin being formed.
At the doubling mill these threads are submitted to finishing processes, by which they may be polished and cleared and finally wound upon small bobbins or spools ready for the market, as seen in Fig. 2.
A fair proportion of the very best yarns are utilised in the manufacture of lace and to imitate silk. Such yarns are usually passed through what is termed a "gassing" machine. In this process each thread is passed rapidly several times through a gas flame usually emanating from a burner of the Bunsen type. The passage of the thread through the flame is too rapid to allow of the burning down of the threads, but is not too quickly to prevent the loose oozy fibres, present more or less on the surface of all cotton yarns, to be burned away. This process is somewhat expensive, as it burns away perhaps 6 pounds weight of yarn in every 100 pounds. This, however, is obtained back again by the increased price of the yarn. It is a property of the cotton fibre that it can be made to imitate more or less either woollen, linen or silk goods, and since cotton is the cheapest fibre of the lot it follows that a considerable amount of cotton yarn is used in combination with these other fibres, in order to produce cheaper fabrics. Embroidery, crocheting and knitting cottons, and the hosiery trade absorb a large amount of the spun cotton yarn; the latter being doubled in most cases in order to fit it for the special work it is designed to do.
In a modern spinning mill the ground floor usually contains the openers, scutchers, drawing frames, carding engines and bobbin and fly-frames. The upper floors are usually covered by mules and other spinning frames.