COTTON MANUFACTURE. (Filature de Coton, Fr.;Baumwollespinnerei,Germ.) Cotton is a filamentous down, which invests the seeds of the plant calledgossypiumby Linnæus, and placed by him in the classmonadelphiaand ordermonandria, but belonging to the natural family ofmalvaceæ. It has a cup-shaped calyx, obtusely five-toothed, inclosed in a three-cleft exterior calyx; the leaflets are united at their base, of a heart shape and toothed; stigmas three to five; capsule three to five celled and many-seeded; seeds bearing a downy wool. Thirteen species are described by Decandolle, but their characters are very uncertain, and no botanist can assign to a definite species of the plant, the very dissimilar staples of the cotton filaments found in commerce. The leaves are generally palmate and hairy; and the blossoms are large, and of a beautiful yellow. Thegossypium religiosumof Tranquebar has white blossoms in some of its varieties, to which, probably, the white cotton of Rome, cultivated in the Jardin des Plantes at Paris, belongs. The filaments differ in length, flexibility, tenacity, and thickness, in different cottons, whence the great differences of their value to the cotton-spinner, as the prices current in the market show. Thus, at Liverpool, on the 1st of December, 1835, the following values were assigned to the following cottons:—s.d.s.d.Sea-island16to26Demerara and Berbice0910Pernambuco0103⁄4111⁄2Egyptian0111⁄2121⁄2New Orleans071⁄810Bahia081⁄4010Upland Georgia071⁄80111⁄2West Indian073⁄409Surat061⁄808Madras061⁄208Bengal051⁄4061⁄2But it is to be observed, that there are varieties of the Sea-island Georgian cotton, so highly prized by the spinner of fine yarn, as to fetch 3s., 4s., or even 5s.per pound.The filaments of cotton, when examined with a good microscope, are seen to be more or less ribbon-like, and twisted; having a breadth varying from1⁄800of an inch in the strongest Smyrna or candle-wick cotton of the Levant, to1⁄2500of an inch in the finest Sea-island.The main distinction between cottons in the pod, is that of the black seeded, and the green seeded; for the former part with their downy wool very readily to a pair of simple rollers, made to revolve nearly in contact, by the power of the human arm; while the latter retain the wool with much force, and require to be ginned, as the operation is called, by a powerful revolving circular saw-mechanism, usually driven by horse or water power. After the cotton wool is thus separated from the seeds, it is packed in large canvas bags, commonly with the aid of a screw or hydraulic press, into a very dense bale, for the convenience of transport. Each of the American bags contains about 340 lbs. of cotton wool. When this cotton is delivered to the manufacturer, it is so foul and flocky, that he must clean and disentangle it with the utmost care, before he can subject it to the carding operation.Cotton ginFig.317.A B, is a roller, about 9 inches in diameter, which revolves in the direction of the arrow. This cylinder consists of a parallel series of oblique pointed circular saws made fast to one axis, and parted from each other by wooden rings nearly one inch and a half in thickness. Above the cylinder is a kind of hopperE F, into which ginner throws the seed cotton, which falls upon a grating, up though which small segments of the saw-teeth project, so as to lay hold of the fibres in their revolution, and pull them through, while the seeds being thus separated, roll down the slope of the grid, to be discharged from the spoutI K.Mis a cylindrical brush placed below the grating, which revolves against the saw teeth, so as to clear them of the adhering cotton filaments.Thewillow, which was originally a cylindrical willow basket, whence its name, but is now a box made of wood, with revolving iron spikes, is the first apparatus to which cotton wool is exposed, after it has been opened up, picked, and sorted by hand or a rake, in what is called abing. The willow exercises a winnowing action, loosens the large flocks, and shakes out much of the dirt contained in them. The frame of the willow is about 2 feet wide, and turns with its spikes at the rapid rate of 600 revolutions per minute, whereby it tosses the cotton about with great violence. The heavy impurities fall down through the grid bottom. It is exposed, however, for only a few minutes to the action of this machine. For factories which work up chiefly the coarser and fouler cottons of India, and Upland Georgia, the conical self-acting willow, asconstructed by Mr. Lillie at Manchester, is much employed. In it, the cotton is put in at the narrow end of the truncated cone, which, being spiked, and revolving rapidly within a nearly concentric case upon a horizontal axis, wafts it on towards the wide end, while its impurities are partly shaken out through the grid or perforated bottom, and partly sucked up through revolving squirrel wire cages, by the centrifugal action of a fan. This is a powerful automatic engine, deserving the study of the curious, and is as safe as it is powerful. The cone of this huge machine makes from 400 to 600 turns per minute, and will clean 7200 pounds, or 24 bags, in a day.After shaking out the grosser impurities by the willow, the cotton spinner proceeds to separate each individual filament of cotton wool from its fellow, so as to prepare it for carding, and to free it from every particle of foreign matter, whether lighter or heavier than itself. This second operation is performed by what are called batting (beating), scutching, and blowing machines, which are all now much the same, whatever difference of signification the name may have. Indeed, each machine not only beats, scutches, but blows.Fig.318.exhibits a longitudinal section of a good blowing engine of modern construction. The machine is about 18 or 19 feet long, and three feet across within the case. The whole frame is made of cast-iron, lined with boards, forming a close box, which has merely openings for introducing the raw cotton wool, for taking out the cleansed wool, and removing the dust as it collects at the bottom. These doors are shut during the operation of the machine, but may be opened at pleasure, to allow the interior to be inspected and repaired.Blowing engineFig. 318 enlarged(120 kB)The introduction of the cotton is effected by means of an endless cloth or double apron, which moves in the direction of the arrowa a, at the left end of thefigure, by passing round the continually revolving rollers atbandc. The two rollers ate, being the ones which immediately introduce the cotton into the jaws, as it were, of the machine, are called the feed rollers. The batting arm, or revolving diameter,f e, turns in the direction of the arrow, and strikes the flocks violently as they enter, so as to throw down any heavy particles upon the iron grating or grid atn, while the light cotton filaments are wafted onwards with the wind, from the rotation of the scutcher in the direction of arrowa′, along the second travelling apron, upon which the squirrel cage cylinder presses, and applies the cotton in the form of a lap. Above the cylindric cageh, which turns in the direction of its arrow, there is a pipek, the continuation of the casei. This pipe, though broken off in the figure, communicates by a branch pipe with an air-sucking fan ventilator, not seen in this figure, but explained underFoundry. The cageh, by its rotation, presses down, as we have said, the half-cleaned cotton upon the clotha′, which carries it forward to the second scutcherf′, by the second set of feed rollerse′. The second scutcher throws down the heavy dust upon the second gridn′, through which it falls upon the bottom of the case. The first scutcher makes about 1280 strokes of each of its two arms in a minute; the second 1300. The feed rollers for each are fluted. The feed cloth is either sustained by a board, or is made of parallel spars of wood, to secure it against bagging, which would render thedelivery of the cotton irregular. The feed rollers make 8 turns in the minute, and as their diameter is 11⁄2inches, they will introduce 8 times their circumference, or 37·7 inches of the cotton spread upon the apron in that time. Upon every 12th part of an inch of the cotton, therefore, nearly 3 blows of the scutcher arm will be applied. The second feed rollers move relatively with more slowness, so that for every 2·4 blows of the scutcher, only one twelfth of an inch of cotton wool is presented.The fan is inclosed in a cylindrical case. The wings or vanes revolve from 120 to 150 times in the minute; and while they throw the air out with nearly this velocity at their excentric outlet in the circumference, they cause it to enter, with equal velocity, at the centre. With this centre the squirrel cage is connected by a pipe, as above stated. The sound filaments of the cotton are arrested by the sieve surface of the cylindric cage, and nothing but the broken fragments and the light dust can pass through.The cotton wool in the blowing machine is wafted by the second scutcher into the spacex,w w, provided with a fine grid bottom; or it is sometimes wound up there by rollers into a lap.Infig.318.an additional ventilator is introduced beneath atm,o o, to aid the action of the scutchers in blowing the cotton onwards into the oblong trougha. The outlet of that fan is att; and it draws in the air at its axisq.uandv, are two doors or lids for removing the cleaned cotton wool. This last fan is suppressed in many blowing machines, as the scutching arms supply a sufficient stream of air. The dotted lines show how the motion is transmitted from the first mover ats, to the various parts of the machine.6′6′represent the bands leading to the main shafting of the mill. A machine of this kind can clean fully 600 pounds of short-stapled cotton wool in a day, with the superintendence of one operative, usually a young woman, to distribute the cotton upon the first feed cloth.Blowing machineFig. 319 enlarged(123 kB)The second Blowing machine is usually called alapmachine, because, after blowing and scutching the cotton, as above described, it eventually coils the fleece upon a wooden roller at the delivering end of the apparatus. It is sometimes also called aspreading machine. A section of it is shown infig.319.The breadth of this machine is about 3 feet as the lap formed is prepared for the usual breadth of the breaker cards, namely 3 feet. Where the cards are only 18 inches broad, the lap machine is also made of the same breadth. In the figure we see the feed-cloth, the scutching barrel, the squirrel suction, and spreading cage, and the rollers for coiling up the lap. The lever shown below is for removing the pressure weight from the axis of the laprollers, when a full one is to be removed, and replaced by an empty one.m, at the top, is the commencement of the pipe which leads to the suction fan, or ventilator. The thickness of the lap in this machine must be nicely regulated, as it determines, in a great measure, the grist of the card ends, and even the rovings. In 12 hours such a lap machine will prepare 650 pounds of cotton.Scutching machineFig.320.is the first scutching machine, now never seen except in the oldest factories.A Bis the feed cloth;G HandM Nare the two scutcher frames.Cardingis the next operation in a cotton factory. Cards are destined to disentangle the individual filaments from each other, and to lay them lengthwise, instead of being doubled up and convoluted, as they usually are in leaving the blowing and lap machines. Carding consists in the mutual action of two opposite surfaces, which are studded thick with oblique angled hooks. The wires of which these hooks are made must be very hard drawn in order to render them stiff and elastic. The middle part of the figures shows one of the staples or double teeth, the structure of which has been partly explained underCard. Supposea,fig.321.to be a piece of a card fillet, andbto be another piece, each being made fast with pins to a board; the teeth of these two cards are set in opposite directions, but are very near together, and parallel. Now suppose a flock or tuft of cotton placed between two such bristling surfaces. Letabe moved in the direction of its arrow, and letbbe moved in the opposite direction, or even let it remain at rest. Every filament of the cotton will be laid hold of by each set of teeth, when their surfaces are thus drawn over each other; the teeth ofawill pull them in a forward direction, while those ofbwill tend to retain them, or to pull them backwards. The loops or doublings will, by both movements, be opened or drawn out, so that the flocks will be converted into rows of parallel filaments, lying alongside or before each other. Each tooth will secure to itself one or more of them, and by the friction of its sides, as well as the hooks of its points, will draw them to their utmost elongation. Though one stroke of the opposite cards be inadequate to produce this equable arrangement, yet many repeated strokes must infallibly accomplish the end in view, of laying the fibres parallel.CardLet us suppose this end effected, and that all the fibres have been transferred to the carda, a transverse stroke ofbwill draw over to it a certain number of them, and indeed at each stroke there will be a new partition between the two cards, with increased parallelism, but still each card will retain a great deal of the cotton. To make one card strip another, the teeth of one of them must be placed in a reverse position, as shown infig.322.Ifabe now drawn in the direction of its arrow along the face ofb, it will inevitably comb out all, or almost all, the filaments from it, since the hooks ofbhave, in this position, no power of retaining them. Even the doubled fibres or loops will slip over the sloping point ofb, in obedience to the traction ofa. By considering these two relative positions of the cards, which take place in hand cards, simply by reversing one of them, any person will be able to understand the play of a cylinder card against its flat top, or against another cylinder card, the respective teeth being in what we may call the teazing position offig.321.; and also the play of a cylinder card against the doffer cylinder, in what may be called the stripping position offig.322.Cylinder cards, so essential to the continuity and dispatch of cotton factory labour, were the ingenious invention of Lewis Paul of Northampton, but were greatly improved and brought into nearly their present operative state by Sir Richard Arkwright. Acarding engine consists of one or more cylinders, covered with card-leather (sometimes called card cloth), and a set of plane surfaces similarly covered, made to work against each other, but so that their points do not come into absolute contact. Some cards consist entirely of cylinders, the central main cylinder being surrounded by a series of smaller ones called urchins or squirrels. These are used solely for preparing the coarser stapled cotton, and sheep’s wool for the wool spinner.Fig.323.represents a card of excellent construction, which may be called abreakerandfinisher, as it is capable of working up the fleece roll of the lapping machine directly into a card-end or riband fit for the drawing machine. In fine spinning mills there are always, however, two cards; one coarser, called a breaker, which turns off the cotton in a broad fleece of extreme thinness, which is lapped round a cylinder; and constitutes the material presented to the finisher card, which has teeth of a finer construction.Carding machineais one of the two upright slots, which are fixed at each side of the engine for receiving the iron gudgeons of the wooden cylinders round which the fleece of the lapping machine is rolled. The circumference of this coil rests upon a rollerb, which is made to turn slowly in such a direction as to aid the unfolding of the lap by the fluted cylinderse. The lap proceeds along the table seen beneath the letterc, in its progress to the fluted rollers, which are an inch and one-sixth in diameter, and have 28 flutings in their circumference.gis a weight which hangs upon the axis of the upper roller, and causes it to press upon the under one:fis the main card drum;g g g, the arch formed by the flat top cards;h, the small card cylinder for stripping off the cotton, and therefore called the doffer, as we have said;i, the doffer-knife or comb for stripping the fleecy web from the doffer;k l q m, the lever mechanism for moving these parts. Atdthere is a door for permitting the tenter to have access to the interior of the engine, and to remove whatever dirt, &c. may happen to fall into it. Infig.324.we see the manner of fixing the flat topsg gover the drum; and for making the matter clearer, three of the tops are removed. Upon the arched cast-iron side of the frame, a row of strong iron pinskare made fast in the middle line; and each top piece has, at each of its ends, a hole, which fits down upon two such opposite pins.l lare screws whose heads serve as supports to the tops, by coming into contact with the bottom of the holes, which are not of course bored through the wood of the tops. By turning the heads of these screws a little the one way or the other, the pins may be lengthened or shortened in any degree, so as to set the tops very truly in adjustment with the drum teeth revolving beneath them,h′is the small runner or urchin, andi′the large runner; both of which are spirally covered from end to end with narrow card fillets, in the same manner as the doffer. The main drum is on the contrary covered with card cloth, in strips laid on parallel to its axis, with interjacent parallel smooth leather borders. The teeth of these several cards are set as represented in the figure, and their cylinders revolve as the arrows indicate. The runners as well as the doffer cylinder may be set nearer to or farther from the drumf; but the screws intended for this adjustment are omitted in the drawings, to avoid confusion of the lines.The card-end or fleece taken off the dofferhby the crank and comb mechanismi k m, passes through the tin plate or brass funneln,fig.323., whereby it is hemmed in and contracted into a riband, which is then passed through between a pair of drawing rollerso. It is next received by the rollersu v, which carry it off with equable velocity, and let it fall into the tin cans placed below, or conduct it over a friction pulley, to be wound along with many other card-ends upon a lap roller or large bobbin. The latter mechanism is not shown in this figure. A sloping curved tin or brass plate, channelled orridged along its surface, conducts the card ribands separately; there are two smooth iron rollers for condensing the several ribands, and a wooden pin round which the ribands are lapped, resting between two leather-covered rollers, one of which receives motion from mill geering, and imparts it by friction to the lap roller over it. The iron ends of the lap roller lie in upright slots, which allow them freedom to rise as the roller gets filled with fleece.The two pairs of rollers ato, effect the extension of the card-end, and reduce its size. The under rollers are made of iron and fluted; the upper ones are also made of iron, but they are covered with a coat of leather, nicely glued on over a coat of flannel, which two coats render them both smooth and elastic. Two weights,w, press the upper cylinders steadily down upon the under ones. Between the first and second pair there is a certain interval, which should be proportioned to the length of the cotton staple. The second, or that furthest from the funnel, revolves with greater velocity than the first, and therefore turns out a greater length of riband than it receives from its fellow; the consequence is a corresponding extension of the riband in the interval between the two pairs of rollers.Carding machineThe motions of the several parts of the engine are effected in the following way. The band,p p,fig.324., which comes down from the pulley upon the main shaft near the ceiling of the work-room, drives, by means of the pulleyq, the drumf,fig.323., with a velocity of from 120 to 140 revolutions in a minute. From another pulleyr, on the axis of the drum, the axis oftis driven by the bandsworking round the pulleyton its end. This shaft drives the crank and lever mechanism of the stripper knifei. A third pulley of the same size asris fixed just within the frame to the other end of the drum, and from it a crossed or close bandr′goes to a pulley upon the small runnerh′, to give this its rapid rotation. Upon the opposite end of the engine infig.323., these wheels and pulleys are marked with dotted lines. Here we may observe, first, a pulleyyupon the drum, and a pulleya′, which receives motion from it by means of the bandz. The axis ofa′, carries in front a pinionm′, which sets in motion the wheeln′. The latter imparts motion, by means of a pinion and intermediate wheelo′, to the wheelhon the doffer cylinder, and consequently to that cylinder on the one hand; and it turns, by the carrier wheelp′, a wheelx, whose axis is marked also withxinfig.323., upon the other hand. The axis ofx′,fig.323., carries, towards the middle of the engine, a very broad wheel, which is represented by a small dotted circle. The toothed wheelvof the smooth rollerv′,fig.323., and the two toothed wheelso o,fig.324., of the under rollerso o,fig.323., work into that broad wheel. The wheel of the second or delivery fluted roller is seen to be smaller than that of the first, by which means the difference of their velocities is obtained. The large runneriis driven from the main drum pulley, by means of the bands′, and the pulleyu′,fig.323.The said band is crossed twice, and is kept in tension by the pulleyt′, round which it passes. The motion of the fluted rollerse, which feed in the cotton fleece, is effected by means of a bevel wheelb′on the end of the doffer, which works into a similar wheelc′on the oblique axisd′(dotted lines across the drum), of the pinione′upon the lower end of the same axis which turns the wheelf′, upon the under feed roller.Each of the feed rollers,fig.324., bears a pinione eat one end, so that the upper roller turns round with the under one. The rollerb,fig.323., is set in motion by means ofits wheelx′; which is driven by a wheelv′on the other end of the under feed roller, through the intervention of the large carrier wheelw′. The original or first motion ofbmust be as quick as that of the fluted feed rollerse, in order that the former may uncoil as much lap as the latter can pass on.The annexed table exhibits the proper velocities of the different cylinders and rollers of the carding engine, which, however, are not invariable, but may be modified according to circumstances, by changing the pinionse′,fig.323., andw′, according to the quality or length of the cotton staple. The velocities stated in the table will be obtained when the pulleya′,fig.323., is made greater thanyin the proportion of 3 to 2, and the wheels and pinions have the following number of teeth:m′, 18;n′, 50; its pinion, 18;h, 128;x, 24; the broad wheel upon the shaft ofx, 37 teeth; the wheeloof the first fluted roller, 35; that of the second, 21;v, 44;b′ande′, 54;e′, 10;f′, 63.Names of the parts.Diameterin inches.Circum-ferencein inches.Revolutionsin oneminute.Velocity.Drumf35109·9130142·87Dofferh1443·964·38192·5Runner or urchini′6·2519·625·98·1Dittoh′3·511·470·5170·Fluted feed rollere1·1673·6640·6962·55First drawing rollero1·3·1468·71215·75Second ditto1·1673·664114·52419·6Smooth delivery rollerv2·57·8554·66429·08The operation of the runners,h′andi′, becomes very plain on comparing their speed with one another and with that of the main-drum, and taking into account the direction of the card teeth. The cotton wool, taken off from the feed-rollers by the drum, is caught by the opposite teeth of the large runneri′, which, on account of its slower surface rotation (98 inches per minute) may be considered to be at rest with reference to the drum, and therefore, by holding the cotton in its teeth, will commence its carding. The small runnerh′, in consequence of its greater surface velocity (5170 inches per minute) will comb the cotton-wool back out of the teeth of the large runner, but it will give it up in its turn to the swifter teeth of the drum, which, in carrying it forwards, encounters the teeth of the top cards, and delivers up the filaments to their keeping for some time. We thus see how essential the runners are to the perfection as well as to the acceleration of the carding process for ordinary cotton wool, though for the slenderer and longer filaments of the sea-island kind they are not so well adapted. In cleaning the carding-engines the little runner must be looked to every time that the drum is examined. The large runner and the doffer require to be cleaned together. The quantity of cotton spread upon the feed-cloth, the velocity of it, and of the drawing-rollers, must all be carefully adjusted to the grist of the yarn intended to be spun.Card and fleeceSuppose the sizes and velocities to be as represented in the preceding table, that the engine is a double card 36 inches broad, and that it is furnished with a lap from the lap-machine of which 30 feet in length weigh 5 lbs. In one minute the surface of the feed-rollers,e, passes 2·55 inches of that lap onwards; in the same time the main drumfwill work it off. To card the whole 30 feet, therefore, 141 minutes, or 2 hours and 21 minutes will be required. In this time the circumference of the rollers,u v, moves through a space of 141 × 42,908 in. = 5042 ft., and delivers a card-end of that length, weighing 5 lbs.,minus6 per cent. for waste, that is 4 lbs. 111⁄2oz. One pound will form a riband 1072 feet long, being, according to the English mode of counting, about number1⁄3, or 0·357. The extension of the cotton-fleece to this degree proceeds as follows:—In the 141 minutes which the feed-rollers take to introduce the 30 feet of lap, the doffer,h, makes 617·58 revolutions, and the comb, or doffer knife,i, detaches from the doffer teeth, a thin fleecy web of 2262 feet in length. The first drawing pair of fluted rollers, by its quick motion, with the aid of the funnel,m, converts this fleece into a riband 2535 feet long. The second pair of the fluted rollers extends this riband to 4390 feet, since their surface velocity is greater than the first pair in that proportion. The slight elongation (of only 112 feet, or about1⁄44) which takes place between the delivery fluted rollers and the smooth cylinders,v,u, serves merely to keep the card-end steadily upon the stretch without folding.Fig.325.is a plan of the card and the fleece, wherehis the cylinder,nis the funnel,uthe pressing rollers, andh′the card-ends in the can.Carding machineFigs.326,327.represent skeletons of the old cards to facilitate the comprehension of these complex machines.Fig.326.is a plan;Fis the main drum;M Mis the doffer knife or comb;G, the carded fleece hemmed in by the funnela, pressed between the rollersb, and then falling in narrow fillets into its can.Fig.327.K Lare the feed rollers;A B, the card drum;C D, the tops;E F, the doffer card;M N, the doffer knife;d,b,c, the card-end passing between compressing rollers into the cana.The drawing and doublingare the next operation. The ends, as they come from the cards, are exceedingly tender and loose, but the filaments of the cotton are not as yet laid so parallel with each other as they need to be for machine spinning. Before any degree of torsion therefore be communicated, a previous process is required to give the filaments a level arrangement in the ribands. The drawing out and doubling accomplish this purpose, and in a manner equally simple and certain. The means employed are drawing-rollers, whose construction must here be fully explained, as it is employed in all the following machines; one example of their use occurred, indeed, in treating of the cards.Drawing out mechanismLetaandb,fig.328., represent the section of two rollers lying over each other, which touch with a regulated pressure, and turn in contact upon their axes, in the direction shown by the arrows. These rollers will lay hold of the fleecy riband presented to them ata, draw it through between them, and deliver it quite unchanged. The length of the piece passed through in a given time will be equal to the space which a point upon the circumference of the roller would have percured in the same time; that is, equal to the periphery of one of the rollers multiplied by the number of its entire revolutions. The same thing holds with regard to the transmission of the riband through between a second pair of rollers,c,d, and a third,e,f. Thus the said riband issues from the third pair exactly the same as it entered ata, provided the surface speed of all the rollers be the same. But if the surface speed ofcanddbe greater than that ofaandb, then the first-named pair will deliver a greater length of riband than the last receives and transmits to it. The consequence can be nothing else in these circumstances than a regulated drawing or elongation of the riband in the interval betwixta,b, andc,d, and a condensation of the filaments as they glide over each other, to assume a straight parallel direction. In like manner the drawing may be repeated by giving the rollers,e,f, a greater surface speed than that of the rollers,candd. This increase of velocity may be produced, either by enlarging the diameter, or by increasing the number of turns in the same time, or finally by both methods conjoined. In general the drawing-machine is so adjusted, that the chief elongation takes place between the second and third pairs of rollers, while that between the first and second is but slight and preparatory. It is obvious, besides, that the speed of the middle pair of rollers can have no influence upon the amount of the extension, provided the speed of the first and third pair remains unchanged. The rollers,a,b, andc,d, maintain towards each other continually the same position, but they may be removed with their frame-work, more or less, from the third pair,e,f, according as the length of the cotton staple may require. The distance of the middle point frombandd, or its line of contact with the upper roller, is, once for all, so calculated, that it shall exceed the length of the cotton filaments, and thereby that these filaments are never in danger of being torn asunder by the second pair pulling them while the first holds them fast. Betweendandf, where the greatest extension takes place, the distance must be as small as it can be without risk of tearing them in that way; for thus will the uniformity of the drawing be promoted. If the distance betweendandfbe very great, a riband passing through will become thinner, or perhaps break in the middle; whence we see that the drawing is more equable, the shorter is the portion submitted to extension at a time, and the nearer the rollers are to each other, supposing them always distant enough not to tear the staple.The under rollersb d fare made of iron, and, to enable them to lay firmer hold of the filaments, their surfaces are fluted with triangular channels parallel to their axes. The upper rollers,a c e, are also made of iron, but they are smooth, and covered with a double coating, which gives them a certain degree of softness and elasticity. A coat of flannel is first applied by sewing or gluing the ends, and then a coat of leather in the same way. The junction edges of the leather are cut slanting, so that when joined by the glue (made of isinglass dissolved in ale) the surface of the roller may be smoothly cylindrical. The top rollers are sometimes called thepressers, because they press by means of weights upon the under ones. These weights are suspended to the slight rodskk′; of which the former operates on the rollerealone, the latter on the two rollersaandetogether. For this purpose the former is hung to aCshaped curvei, whose upper hook embraces the rollere; the latter to a brass saddleh, which rests uponaandc. A bar of hard wood,g, whose under surface is covered with flannel, rests, with merely its own weight, upon the top rollers, and strips off all the loose hanging filaments. Similar bars with the same view are made to bear up under the fluted rollersb d f, and press against them by a weight acting through a cord passing over a pulley. Instead of the upper dust-covers, light wooden rollers covered with flannel are occasionally applied.Were the drawing of a riband continued till all its fibres acquired the desired degree of parallelism, it would be apt, from excessive attenuation, to tear across, and thereby to defeat the purpose of the spinner. This dilemma is got rid of in a very simple way, namely, by laying several ribands together at every repetition of the process, and incorporating them by the pressure of the rollers. This practice is calleddoubling. It is an exact imitation of what takes place when we draw a tuft of cotton wool between our fingers and thumb in order to ascertain the length of the staple, and replace the drawn filaments over each other, and thus draw them forth again and again, till they are all parallel and of nearly equal length. The doubling has another advantage, that of causing the inequalities of thickness in the ribands to disappear, by applying their thicker to their thinner portions, and thereby producing uniformity of substance.
COTTON MANUFACTURE. (Filature de Coton, Fr.;Baumwollespinnerei,Germ.) Cotton is a filamentous down, which invests the seeds of the plant calledgossypiumby Linnæus, and placed by him in the classmonadelphiaand ordermonandria, but belonging to the natural family ofmalvaceæ. It has a cup-shaped calyx, obtusely five-toothed, inclosed in a three-cleft exterior calyx; the leaflets are united at their base, of a heart shape and toothed; stigmas three to five; capsule three to five celled and many-seeded; seeds bearing a downy wool. Thirteen species are described by Decandolle, but their characters are very uncertain, and no botanist can assign to a definite species of the plant, the very dissimilar staples of the cotton filaments found in commerce. The leaves are generally palmate and hairy; and the blossoms are large, and of a beautiful yellow. Thegossypium religiosumof Tranquebar has white blossoms in some of its varieties, to which, probably, the white cotton of Rome, cultivated in the Jardin des Plantes at Paris, belongs. The filaments differ in length, flexibility, tenacity, and thickness, in different cottons, whence the great differences of their value to the cotton-spinner, as the prices current in the market show. Thus, at Liverpool, on the 1st of December, 1835, the following values were assigned to the following cottons:—
But it is to be observed, that there are varieties of the Sea-island Georgian cotton, so highly prized by the spinner of fine yarn, as to fetch 3s., 4s., or even 5s.per pound.
The filaments of cotton, when examined with a good microscope, are seen to be more or less ribbon-like, and twisted; having a breadth varying from1⁄800of an inch in the strongest Smyrna or candle-wick cotton of the Levant, to1⁄2500of an inch in the finest Sea-island.
The main distinction between cottons in the pod, is that of the black seeded, and the green seeded; for the former part with their downy wool very readily to a pair of simple rollers, made to revolve nearly in contact, by the power of the human arm; while the latter retain the wool with much force, and require to be ginned, as the operation is called, by a powerful revolving circular saw-mechanism, usually driven by horse or water power. After the cotton wool is thus separated from the seeds, it is packed in large canvas bags, commonly with the aid of a screw or hydraulic press, into a very dense bale, for the convenience of transport. Each of the American bags contains about 340 lbs. of cotton wool. When this cotton is delivered to the manufacturer, it is so foul and flocky, that he must clean and disentangle it with the utmost care, before he can subject it to the carding operation.
Cotton gin
Fig.317.A B, is a roller, about 9 inches in diameter, which revolves in the direction of the arrow. This cylinder consists of a parallel series of oblique pointed circular saws made fast to one axis, and parted from each other by wooden rings nearly one inch and a half in thickness. Above the cylinder is a kind of hopperE F, into which ginner throws the seed cotton, which falls upon a grating, up though which small segments of the saw-teeth project, so as to lay hold of the fibres in their revolution, and pull them through, while the seeds being thus separated, roll down the slope of the grid, to be discharged from the spoutI K.Mis a cylindrical brush placed below the grating, which revolves against the saw teeth, so as to clear them of the adhering cotton filaments.
Thewillow, which was originally a cylindrical willow basket, whence its name, but is now a box made of wood, with revolving iron spikes, is the first apparatus to which cotton wool is exposed, after it has been opened up, picked, and sorted by hand or a rake, in what is called abing. The willow exercises a winnowing action, loosens the large flocks, and shakes out much of the dirt contained in them. The frame of the willow is about 2 feet wide, and turns with its spikes at the rapid rate of 600 revolutions per minute, whereby it tosses the cotton about with great violence. The heavy impurities fall down through the grid bottom. It is exposed, however, for only a few minutes to the action of this machine. For factories which work up chiefly the coarser and fouler cottons of India, and Upland Georgia, the conical self-acting willow, asconstructed by Mr. Lillie at Manchester, is much employed. In it, the cotton is put in at the narrow end of the truncated cone, which, being spiked, and revolving rapidly within a nearly concentric case upon a horizontal axis, wafts it on towards the wide end, while its impurities are partly shaken out through the grid or perforated bottom, and partly sucked up through revolving squirrel wire cages, by the centrifugal action of a fan. This is a powerful automatic engine, deserving the study of the curious, and is as safe as it is powerful. The cone of this huge machine makes from 400 to 600 turns per minute, and will clean 7200 pounds, or 24 bags, in a day.
After shaking out the grosser impurities by the willow, the cotton spinner proceeds to separate each individual filament of cotton wool from its fellow, so as to prepare it for carding, and to free it from every particle of foreign matter, whether lighter or heavier than itself. This second operation is performed by what are called batting (beating), scutching, and blowing machines, which are all now much the same, whatever difference of signification the name may have. Indeed, each machine not only beats, scutches, but blows.Fig.318.exhibits a longitudinal section of a good blowing engine of modern construction. The machine is about 18 or 19 feet long, and three feet across within the case. The whole frame is made of cast-iron, lined with boards, forming a close box, which has merely openings for introducing the raw cotton wool, for taking out the cleansed wool, and removing the dust as it collects at the bottom. These doors are shut during the operation of the machine, but may be opened at pleasure, to allow the interior to be inspected and repaired.
Blowing engineFig. 318 enlarged(120 kB)
Fig. 318 enlarged(120 kB)
The introduction of the cotton is effected by means of an endless cloth or double apron, which moves in the direction of the arrowa a, at the left end of thefigure, by passing round the continually revolving rollers atbandc. The two rollers ate, being the ones which immediately introduce the cotton into the jaws, as it were, of the machine, are called the feed rollers. The batting arm, or revolving diameter,f e, turns in the direction of the arrow, and strikes the flocks violently as they enter, so as to throw down any heavy particles upon the iron grating or grid atn, while the light cotton filaments are wafted onwards with the wind, from the rotation of the scutcher in the direction of arrowa′, along the second travelling apron, upon which the squirrel cage cylinder presses, and applies the cotton in the form of a lap. Above the cylindric cageh, which turns in the direction of its arrow, there is a pipek, the continuation of the casei. This pipe, though broken off in the figure, communicates by a branch pipe with an air-sucking fan ventilator, not seen in this figure, but explained underFoundry. The cageh, by its rotation, presses down, as we have said, the half-cleaned cotton upon the clotha′, which carries it forward to the second scutcherf′, by the second set of feed rollerse′. The second scutcher throws down the heavy dust upon the second gridn′, through which it falls upon the bottom of the case. The first scutcher makes about 1280 strokes of each of its two arms in a minute; the second 1300. The feed rollers for each are fluted. The feed cloth is either sustained by a board, or is made of parallel spars of wood, to secure it against bagging, which would render thedelivery of the cotton irregular. The feed rollers make 8 turns in the minute, and as their diameter is 11⁄2inches, they will introduce 8 times their circumference, or 37·7 inches of the cotton spread upon the apron in that time. Upon every 12th part of an inch of the cotton, therefore, nearly 3 blows of the scutcher arm will be applied. The second feed rollers move relatively with more slowness, so that for every 2·4 blows of the scutcher, only one twelfth of an inch of cotton wool is presented.
The fan is inclosed in a cylindrical case. The wings or vanes revolve from 120 to 150 times in the minute; and while they throw the air out with nearly this velocity at their excentric outlet in the circumference, they cause it to enter, with equal velocity, at the centre. With this centre the squirrel cage is connected by a pipe, as above stated. The sound filaments of the cotton are arrested by the sieve surface of the cylindric cage, and nothing but the broken fragments and the light dust can pass through.
The cotton wool in the blowing machine is wafted by the second scutcher into the spacex,w w, provided with a fine grid bottom; or it is sometimes wound up there by rollers into a lap.
Infig.318.an additional ventilator is introduced beneath atm,o o, to aid the action of the scutchers in blowing the cotton onwards into the oblong trougha. The outlet of that fan is att; and it draws in the air at its axisq.uandv, are two doors or lids for removing the cleaned cotton wool. This last fan is suppressed in many blowing machines, as the scutching arms supply a sufficient stream of air. The dotted lines show how the motion is transmitted from the first mover ats, to the various parts of the machine.6′6′represent the bands leading to the main shafting of the mill. A machine of this kind can clean fully 600 pounds of short-stapled cotton wool in a day, with the superintendence of one operative, usually a young woman, to distribute the cotton upon the first feed cloth.
Blowing machineFig. 319 enlarged(123 kB)
Fig. 319 enlarged(123 kB)
The second Blowing machine is usually called alapmachine, because, after blowing and scutching the cotton, as above described, it eventually coils the fleece upon a wooden roller at the delivering end of the apparatus. It is sometimes also called aspreading machine. A section of it is shown infig.319.The breadth of this machine is about 3 feet as the lap formed is prepared for the usual breadth of the breaker cards, namely 3 feet. Where the cards are only 18 inches broad, the lap machine is also made of the same breadth. In the figure we see the feed-cloth, the scutching barrel, the squirrel suction, and spreading cage, and the rollers for coiling up the lap. The lever shown below is for removing the pressure weight from the axis of the laprollers, when a full one is to be removed, and replaced by an empty one.m, at the top, is the commencement of the pipe which leads to the suction fan, or ventilator. The thickness of the lap in this machine must be nicely regulated, as it determines, in a great measure, the grist of the card ends, and even the rovings. In 12 hours such a lap machine will prepare 650 pounds of cotton.
Scutching machine
Fig.320.is the first scutching machine, now never seen except in the oldest factories.A Bis the feed cloth;G HandM Nare the two scutcher frames.
Cardingis the next operation in a cotton factory. Cards are destined to disentangle the individual filaments from each other, and to lay them lengthwise, instead of being doubled up and convoluted, as they usually are in leaving the blowing and lap machines. Carding consists in the mutual action of two opposite surfaces, which are studded thick with oblique angled hooks. The wires of which these hooks are made must be very hard drawn in order to render them stiff and elastic. The middle part of the figures shows one of the staples or double teeth, the structure of which has been partly explained underCard. Supposea,fig.321.to be a piece of a card fillet, andbto be another piece, each being made fast with pins to a board; the teeth of these two cards are set in opposite directions, but are very near together, and parallel. Now suppose a flock or tuft of cotton placed between two such bristling surfaces. Letabe moved in the direction of its arrow, and letbbe moved in the opposite direction, or even let it remain at rest. Every filament of the cotton will be laid hold of by each set of teeth, when their surfaces are thus drawn over each other; the teeth ofawill pull them in a forward direction, while those ofbwill tend to retain them, or to pull them backwards. The loops or doublings will, by both movements, be opened or drawn out, so that the flocks will be converted into rows of parallel filaments, lying alongside or before each other. Each tooth will secure to itself one or more of them, and by the friction of its sides, as well as the hooks of its points, will draw them to their utmost elongation. Though one stroke of the opposite cards be inadequate to produce this equable arrangement, yet many repeated strokes must infallibly accomplish the end in view, of laying the fibres parallel.
Card
Let us suppose this end effected, and that all the fibres have been transferred to the carda, a transverse stroke ofbwill draw over to it a certain number of them, and indeed at each stroke there will be a new partition between the two cards, with increased parallelism, but still each card will retain a great deal of the cotton. To make one card strip another, the teeth of one of them must be placed in a reverse position, as shown infig.322.
Ifabe now drawn in the direction of its arrow along the face ofb, it will inevitably comb out all, or almost all, the filaments from it, since the hooks ofbhave, in this position, no power of retaining them. Even the doubled fibres or loops will slip over the sloping point ofb, in obedience to the traction ofa. By considering these two relative positions of the cards, which take place in hand cards, simply by reversing one of them, any person will be able to understand the play of a cylinder card against its flat top, or against another cylinder card, the respective teeth being in what we may call the teazing position offig.321.; and also the play of a cylinder card against the doffer cylinder, in what may be called the stripping position offig.322.
Cylinder cards, so essential to the continuity and dispatch of cotton factory labour, were the ingenious invention of Lewis Paul of Northampton, but were greatly improved and brought into nearly their present operative state by Sir Richard Arkwright. Acarding engine consists of one or more cylinders, covered with card-leather (sometimes called card cloth), and a set of plane surfaces similarly covered, made to work against each other, but so that their points do not come into absolute contact. Some cards consist entirely of cylinders, the central main cylinder being surrounded by a series of smaller ones called urchins or squirrels. These are used solely for preparing the coarser stapled cotton, and sheep’s wool for the wool spinner.
Fig.323.represents a card of excellent construction, which may be called abreakerandfinisher, as it is capable of working up the fleece roll of the lapping machine directly into a card-end or riband fit for the drawing machine. In fine spinning mills there are always, however, two cards; one coarser, called a breaker, which turns off the cotton in a broad fleece of extreme thinness, which is lapped round a cylinder; and constitutes the material presented to the finisher card, which has teeth of a finer construction.
Carding machine
ais one of the two upright slots, which are fixed at each side of the engine for receiving the iron gudgeons of the wooden cylinders round which the fleece of the lapping machine is rolled. The circumference of this coil rests upon a rollerb, which is made to turn slowly in such a direction as to aid the unfolding of the lap by the fluted cylinderse. The lap proceeds along the table seen beneath the letterc, in its progress to the fluted rollers, which are an inch and one-sixth in diameter, and have 28 flutings in their circumference.gis a weight which hangs upon the axis of the upper roller, and causes it to press upon the under one:fis the main card drum;g g g, the arch formed by the flat top cards;h, the small card cylinder for stripping off the cotton, and therefore called the doffer, as we have said;i, the doffer-knife or comb for stripping the fleecy web from the doffer;k l q m, the lever mechanism for moving these parts. Atdthere is a door for permitting the tenter to have access to the interior of the engine, and to remove whatever dirt, &c. may happen to fall into it. Infig.324.we see the manner of fixing the flat topsg gover the drum; and for making the matter clearer, three of the tops are removed. Upon the arched cast-iron side of the frame, a row of strong iron pinskare made fast in the middle line; and each top piece has, at each of its ends, a hole, which fits down upon two such opposite pins.l lare screws whose heads serve as supports to the tops, by coming into contact with the bottom of the holes, which are not of course bored through the wood of the tops. By turning the heads of these screws a little the one way or the other, the pins may be lengthened or shortened in any degree, so as to set the tops very truly in adjustment with the drum teeth revolving beneath them,h′is the small runner or urchin, andi′the large runner; both of which are spirally covered from end to end with narrow card fillets, in the same manner as the doffer. The main drum is on the contrary covered with card cloth, in strips laid on parallel to its axis, with interjacent parallel smooth leather borders. The teeth of these several cards are set as represented in the figure, and their cylinders revolve as the arrows indicate. The runners as well as the doffer cylinder may be set nearer to or farther from the drumf; but the screws intended for this adjustment are omitted in the drawings, to avoid confusion of the lines.
The card-end or fleece taken off the dofferhby the crank and comb mechanismi k m, passes through the tin plate or brass funneln,fig.323., whereby it is hemmed in and contracted into a riband, which is then passed through between a pair of drawing rollerso. It is next received by the rollersu v, which carry it off with equable velocity, and let it fall into the tin cans placed below, or conduct it over a friction pulley, to be wound along with many other card-ends upon a lap roller or large bobbin. The latter mechanism is not shown in this figure. A sloping curved tin or brass plate, channelled orridged along its surface, conducts the card ribands separately; there are two smooth iron rollers for condensing the several ribands, and a wooden pin round which the ribands are lapped, resting between two leather-covered rollers, one of which receives motion from mill geering, and imparts it by friction to the lap roller over it. The iron ends of the lap roller lie in upright slots, which allow them freedom to rise as the roller gets filled with fleece.
The two pairs of rollers ato, effect the extension of the card-end, and reduce its size. The under rollers are made of iron and fluted; the upper ones are also made of iron, but they are covered with a coat of leather, nicely glued on over a coat of flannel, which two coats render them both smooth and elastic. Two weights,w, press the upper cylinders steadily down upon the under ones. Between the first and second pair there is a certain interval, which should be proportioned to the length of the cotton staple. The second, or that furthest from the funnel, revolves with greater velocity than the first, and therefore turns out a greater length of riband than it receives from its fellow; the consequence is a corresponding extension of the riband in the interval between the two pairs of rollers.
Carding machine
The motions of the several parts of the engine are effected in the following way. The band,p p,fig.324., which comes down from the pulley upon the main shaft near the ceiling of the work-room, drives, by means of the pulleyq, the drumf,fig.323., with a velocity of from 120 to 140 revolutions in a minute. From another pulleyr, on the axis of the drum, the axis oftis driven by the bandsworking round the pulleyton its end. This shaft drives the crank and lever mechanism of the stripper knifei. A third pulley of the same size asris fixed just within the frame to the other end of the drum, and from it a crossed or close bandr′goes to a pulley upon the small runnerh′, to give this its rapid rotation. Upon the opposite end of the engine infig.323., these wheels and pulleys are marked with dotted lines. Here we may observe, first, a pulleyyupon the drum, and a pulleya′, which receives motion from it by means of the bandz. The axis ofa′, carries in front a pinionm′, which sets in motion the wheeln′. The latter imparts motion, by means of a pinion and intermediate wheelo′, to the wheelhon the doffer cylinder, and consequently to that cylinder on the one hand; and it turns, by the carrier wheelp′, a wheelx, whose axis is marked also withxinfig.323., upon the other hand. The axis ofx′,fig.323., carries, towards the middle of the engine, a very broad wheel, which is represented by a small dotted circle. The toothed wheelvof the smooth rollerv′,fig.323., and the two toothed wheelso o,fig.324., of the under rollerso o,fig.323., work into that broad wheel. The wheel of the second or delivery fluted roller is seen to be smaller than that of the first, by which means the difference of their velocities is obtained. The large runneriis driven from the main drum pulley, by means of the bands′, and the pulleyu′,fig.323.The said band is crossed twice, and is kept in tension by the pulleyt′, round which it passes. The motion of the fluted rollerse, which feed in the cotton fleece, is effected by means of a bevel wheelb′on the end of the doffer, which works into a similar wheelc′on the oblique axisd′(dotted lines across the drum), of the pinione′upon the lower end of the same axis which turns the wheelf′, upon the under feed roller.
Each of the feed rollers,fig.324., bears a pinione eat one end, so that the upper roller turns round with the under one. The rollerb,fig.323., is set in motion by means ofits wheelx′; which is driven by a wheelv′on the other end of the under feed roller, through the intervention of the large carrier wheelw′. The original or first motion ofbmust be as quick as that of the fluted feed rollerse, in order that the former may uncoil as much lap as the latter can pass on.
The annexed table exhibits the proper velocities of the different cylinders and rollers of the carding engine, which, however, are not invariable, but may be modified according to circumstances, by changing the pinionse′,fig.323., andw′, according to the quality or length of the cotton staple. The velocities stated in the table will be obtained when the pulleya′,fig.323., is made greater thanyin the proportion of 3 to 2, and the wheels and pinions have the following number of teeth:m′, 18;n′, 50; its pinion, 18;h, 128;x, 24; the broad wheel upon the shaft ofx, 37 teeth; the wheeloof the first fluted roller, 35; that of the second, 21;v, 44;b′ande′, 54;e′, 10;f′, 63.
The operation of the runners,h′andi′, becomes very plain on comparing their speed with one another and with that of the main-drum, and taking into account the direction of the card teeth. The cotton wool, taken off from the feed-rollers by the drum, is caught by the opposite teeth of the large runneri′, which, on account of its slower surface rotation (98 inches per minute) may be considered to be at rest with reference to the drum, and therefore, by holding the cotton in its teeth, will commence its carding. The small runnerh′, in consequence of its greater surface velocity (5170 inches per minute) will comb the cotton-wool back out of the teeth of the large runner, but it will give it up in its turn to the swifter teeth of the drum, which, in carrying it forwards, encounters the teeth of the top cards, and delivers up the filaments to their keeping for some time. We thus see how essential the runners are to the perfection as well as to the acceleration of the carding process for ordinary cotton wool, though for the slenderer and longer filaments of the sea-island kind they are not so well adapted. In cleaning the carding-engines the little runner must be looked to every time that the drum is examined. The large runner and the doffer require to be cleaned together. The quantity of cotton spread upon the feed-cloth, the velocity of it, and of the drawing-rollers, must all be carefully adjusted to the grist of the yarn intended to be spun.
Card and fleece
Suppose the sizes and velocities to be as represented in the preceding table, that the engine is a double card 36 inches broad, and that it is furnished with a lap from the lap-machine of which 30 feet in length weigh 5 lbs. In one minute the surface of the feed-rollers,e, passes 2·55 inches of that lap onwards; in the same time the main drumfwill work it off. To card the whole 30 feet, therefore, 141 minutes, or 2 hours and 21 minutes will be required. In this time the circumference of the rollers,u v, moves through a space of 141 × 42,908 in. = 5042 ft., and delivers a card-end of that length, weighing 5 lbs.,minus6 per cent. for waste, that is 4 lbs. 111⁄2oz. One pound will form a riband 1072 feet long, being, according to the English mode of counting, about number1⁄3, or 0·357. The extension of the cotton-fleece to this degree proceeds as follows:—In the 141 minutes which the feed-rollers take to introduce the 30 feet of lap, the doffer,h, makes 617·58 revolutions, and the comb, or doffer knife,i, detaches from the doffer teeth, a thin fleecy web of 2262 feet in length. The first drawing pair of fluted rollers, by its quick motion, with the aid of the funnel,m, converts this fleece into a riband 2535 feet long. The second pair of the fluted rollers extends this riband to 4390 feet, since their surface velocity is greater than the first pair in that proportion. The slight elongation (of only 112 feet, or about1⁄44) which takes place between the delivery fluted rollers and the smooth cylinders,v,u, serves merely to keep the card-end steadily upon the stretch without folding.Fig.325.is a plan of the card and the fleece, wherehis the cylinder,nis the funnel,uthe pressing rollers, andh′the card-ends in the can.
Carding machine
Figs.326,327.represent skeletons of the old cards to facilitate the comprehension of these complex machines.Fig.326.is a plan;Fis the main drum;M Mis the doffer knife or comb;G, the carded fleece hemmed in by the funnela, pressed between the rollersb, and then falling in narrow fillets into its can.Fig.327.K Lare the feed rollers;A B, the card drum;C D, the tops;E F, the doffer card;M N, the doffer knife;d,b,c, the card-end passing between compressing rollers into the cana.
The drawing and doublingare the next operation. The ends, as they come from the cards, are exceedingly tender and loose, but the filaments of the cotton are not as yet laid so parallel with each other as they need to be for machine spinning. Before any degree of torsion therefore be communicated, a previous process is required to give the filaments a level arrangement in the ribands. The drawing out and doubling accomplish this purpose, and in a manner equally simple and certain. The means employed are drawing-rollers, whose construction must here be fully explained, as it is employed in all the following machines; one example of their use occurred, indeed, in treating of the cards.
Drawing out mechanism
Letaandb,fig.328., represent the section of two rollers lying over each other, which touch with a regulated pressure, and turn in contact upon their axes, in the direction shown by the arrows. These rollers will lay hold of the fleecy riband presented to them ata, draw it through between them, and deliver it quite unchanged. The length of the piece passed through in a given time will be equal to the space which a point upon the circumference of the roller would have percured in the same time; that is, equal to the periphery of one of the rollers multiplied by the number of its entire revolutions. The same thing holds with regard to the transmission of the riband through between a second pair of rollers,c,d, and a third,e,f. Thus the said riband issues from the third pair exactly the same as it entered ata, provided the surface speed of all the rollers be the same. But if the surface speed ofcanddbe greater than that ofaandb, then the first-named pair will deliver a greater length of riband than the last receives and transmits to it. The consequence can be nothing else in these circumstances than a regulated drawing or elongation of the riband in the interval betwixta,b, andc,d, and a condensation of the filaments as they glide over each other, to assume a straight parallel direction. In like manner the drawing may be repeated by giving the rollers,e,f, a greater surface speed than that of the rollers,candd. This increase of velocity may be produced, either by enlarging the diameter, or by increasing the number of turns in the same time, or finally by both methods conjoined. In general the drawing-machine is so adjusted, that the chief elongation takes place between the second and third pairs of rollers, while that between the first and second is but slight and preparatory. It is obvious, besides, that the speed of the middle pair of rollers can have no influence upon the amount of the extension, provided the speed of the first and third pair remains unchanged. The rollers,a,b, andc,d, maintain towards each other continually the same position, but they may be removed with their frame-work, more or less, from the third pair,e,f, according as the length of the cotton staple may require. The distance of the middle point frombandd, or its line of contact with the upper roller, is, once for all, so calculated, that it shall exceed the length of the cotton filaments, and thereby that these filaments are never in danger of being torn asunder by the second pair pulling them while the first holds them fast. Betweendandf, where the greatest extension takes place, the distance must be as small as it can be without risk of tearing them in that way; for thus will the uniformity of the drawing be promoted. If the distance betweendandfbe very great, a riband passing through will become thinner, or perhaps break in the middle; whence we see that the drawing is more equable, the shorter is the portion submitted to extension at a time, and the nearer the rollers are to each other, supposing them always distant enough not to tear the staple.
The under rollersb d fare made of iron, and, to enable them to lay firmer hold of the filaments, their surfaces are fluted with triangular channels parallel to their axes. The upper rollers,a c e, are also made of iron, but they are smooth, and covered with a double coating, which gives them a certain degree of softness and elasticity. A coat of flannel is first applied by sewing or gluing the ends, and then a coat of leather in the same way. The junction edges of the leather are cut slanting, so that when joined by the glue (made of isinglass dissolved in ale) the surface of the roller may be smoothly cylindrical. The top rollers are sometimes called thepressers, because they press by means of weights upon the under ones. These weights are suspended to the slight rodskk′; of which the former operates on the rollerealone, the latter on the two rollersaandetogether. For this purpose the former is hung to aCshaped curvei, whose upper hook embraces the rollere; the latter to a brass saddleh, which rests uponaandc. A bar of hard wood,g, whose under surface is covered with flannel, rests, with merely its own weight, upon the top rollers, and strips off all the loose hanging filaments. Similar bars with the same view are made to bear up under the fluted rollersb d f, and press against them by a weight acting through a cord passing over a pulley. Instead of the upper dust-covers, light wooden rollers covered with flannel are occasionally applied.
Were the drawing of a riband continued till all its fibres acquired the desired degree of parallelism, it would be apt, from excessive attenuation, to tear across, and thereby to defeat the purpose of the spinner. This dilemma is got rid of in a very simple way, namely, by laying several ribands together at every repetition of the process, and incorporating them by the pressure of the rollers. This practice is calleddoubling. It is an exact imitation of what takes place when we draw a tuft of cotton wool between our fingers and thumb in order to ascertain the length of the staple, and replace the drawn filaments over each other, and thus draw them forth again and again, till they are all parallel and of nearly equal length. The doubling has another advantage, that of causing the inequalities of thickness in the ribands to disappear, by applying their thicker to their thinner portions, and thereby producing uniformity of substance.