SILK MANUFACTURE. (Fabrique de soie, Fr.;Seidenfabrik, Germ.) This may be divided into two branches: 1. the production of raw silk; 2. its filature and preparation in the mill, for the purposes of the weaver and other textile artisans. The threads, as spun by the silkworm, and wound up in its cocoon, are all twins, in consequence of the twin orifice in the nose of the insect through which they are projected. These two threads are laid parallel to each other, and are glued more or less evenly together by a kind of glossy varnish, which also envelopes them, constituting nearly 25 per cent. of their weight. Each ultimate filament measures about1⁄2000of an inch in average fine silk, and the pair measures of course fully1⁄1000of an inch. In the raw silk, as imported from Italy, France, China, &c., several of these twin filaments are slightly twisted and agglutinated to form one thread, called a single.The specific gravity of silk is 1·300, water being 1·000. It is by far the most tenacious or the strongest of all textile fibres, a thread of it of a certain diameter being nearly three times stronger than a thread of flax, and twice stronger than hemp. Some varieties of silk are perfectly white, but the general colour in the native state is a golden yellow.The production of silk was unknown in Europe till the sixth century, when two monks, who brought some eggs of the silkworm from China or India to Constantinople, were encouraged to breed the insect, and cultivate its cocoons, by the Emperor Justinian. Several silk manufactures were in consequence established in Athens, Thebes, and Corinth, not only for rearing the worm upon mulberry-leaves, but for unwinding its cocoons, for twisting their filaments into stronger threads, and weaving these into robes. The Venetians having then and long afterwards intimate commercial relations with the Greek empire, supplied the whole of western Europe with silk goods, and derived great riches from the trade.About 1130, Roger II., king of Sicily, set up a silk manufacture at Palermo, and another in Calabria, conducted by artisans whom he had seized and carried off as prisoners of war in his expedition to the Holy Land. From these countries, the silk industry soon spread throughout Italy. It seems to have been introduced into Spain at a very early period, by the Moors, particularly in Murcia, Cordova, and Granada. The last town, indeed, possessed a flourishing silk trade when it was taken by Ferdinand in the 15th century. The French having been supplied with workmen from Milan, commenced, in 1521, the silk manufacture; but it was not till 1564 that they began successfully to produce the silk itself, when Traucat, a working gardener at Nismes, formed the first nursery of white mulberry-trees, and with such success, that in a few years he was enabled to propagate them over many of the southern provinces of France. Prior to this time, some French noblemen, on their return from the conquest of Naples, had introduced a few silkworms with the mulberry into Dauphiny; but the business had not prospered in their hands. The mulberry plantations were greatly encouraged by Henry IV.; and since then they have been the source of most beneficial employment to the French people. James I. was most solicitous to introduce the breeding of silkworms into England, and in a speech from the throne he earnestly recommended his subjects to plant mulberry-trees; but he totally failed in the project. This country does not seem to be well adapted for this species of husbandry, on account of the great prevalence of blighting east winds during the months of April and May, when the worms require a plentiful supply of mulberry-leaves. The manufacture of silk goods, however, made great progress during that king’s peaceful and pompous reign. In 1629 it had become so considerable in London, that the silk-throwsters of the city and suburbs were formed into a public corporation. So early as 1661 they employed 40,000 persons. The revocation of the edict of Nantes, in 1685, contributed in a remarkable manner to the increase of the English silk trade, by the influx of a large colony of skilful French weavers, who settled in Spitalfields. The great silk-throwing mill mounted at Derby, in 1719, also served to promote the extension of this branch of manufacture; for soonafterwards, in the year 1730, the English silk goods bore a higher price in Italy than those made by the Italians, according to the testimony of Keysler.Till the year 1826, however, our silk manufactures in general laboured under very grievous fiscal burdens. Foreign organzine, or twisted raw silk, paid an import duty of 14s.71⁄2d.per pound; raw Bengal silk, 4s.; and that from other places, 5s.71⁄2d.Mr. Huskisson introduced a bill at that time, reducing the duty on organzine to 5s., and the duty on other raw silk to 3d.per pound. The total prohibition of the import of French manufactured silks, which gave rise to so much contraband trade, was also converted into a duty of 30 per cent.ad valorem. During the reign of the prohibitory system, when our silk weavers had no variety of patterns to imitate, and no adequate stimulus to excel, on account of the monopoly which they possessed in the home market, the inferiority of their productions was a subject of constant pride and congratulation among the Lyonnais; and accordingly the English could not stand their competition any where. At that time, the disadvantage on English silk goods, compared to French, was estimated in foreign markets at 40 per cent.; of late years it certainly does not exceed 20, notwithstanding the many peculiar facilities which France enjoys for this her favourite staple.The silkworm, called by entomologistsPhalæna bombyx mori, is, like its kindred species, subject to four metamorphoses. The egg, fostered by the genial warmth of spring, sends forth a caterpillar, which, in its progressive enlargement, casts its skin either three or four times, according to the variety of the insect. Having acquired its full size in the course of 25 or 30 days, and ceasing to eat during the remainder of its life, it begins to discharge a viscid secretion, in the form of pulpy twin filaments, from its nose, which harden in the air. These threads are instinctively coiled into an ovoid nest round itself, called a cocoon, which serves as a defence against living enemies and changes of temperature. Here it soon changes into the chrysalis or nymph state, in which it lies swaddled, as it were, for about 15 or 20 days. Then it bursts its cearments, and comes forth furnished with appropriate wings, antennæ, and feet, for living in its new element, the atmosphere. The male and the female moths couple together at this time, and terminate their union by a speedy death, their whole existence being limited to two months. The cocoons are completely formed in the course of three or four days; the finest being reserved as seed worms. From these cocoons, after an interval of 18 or 20 days, the moth makes its appearance, perforating its tomb by knocking with its head against one end of the cocoon, after softening it with saliva, and thus rendering the filaments more easily torn asunder by its claws. Such moths or aurelias are collected and placed upon a piece of soft cloth, where they couple and lay their eggs.The eggs, or grains as they are usually termed, are enveloped in a liquid which causes them to adhere to the piece of cloth or paper on which the female lays them. From this glue they are readily freed, by dipping them in cold water, and wiping them dry. They are best preserved in theovumstate at a temperature of about 55° F. If the heat of spring advances rapidly in April, it must not be suffered to act on the eggs, otherwise it might hatch the caterpillars long before the mulberry has sent forth its leaves to nourish them. Another reason for keeping back their incubation is, that they may be hatched together in large broods, and not by small numbers in succession. The eggs are made up into small packets, of an ounce, or somewhat more, which in the south of France are generally attached to the girdles of the women during the day, and placed under their pillows at night. They are, of course, carefully examined from time to time. In large establishments, they are placed in an appropriate stove-room, where they are exposed to a temperature gradually increased till it reaches the 86th degree of Fahrenheit’s scale, which term it must not exceed. Aided by this heat, nature completes her mysterious work of incubation in eight or ten days. The teeming eggs are now covered with a sheet of paper pierced with numerous holes, about one-twelfth of an inch in diameter. Through these apertures the new-hatched worms creep upwards instinctively, to get at the tender mulberry leaves strewed over the paper.The nursery where the worms are reared, is called by the French amagnanière; it ought to be a well-aired chamber, free from damp, excess of cold or heat, rats and other vermin. It should be ventilated occasionally, to purify the atmosphere from the noisome emanations produced by the excrements of the caterpillars and the decayed leaves. The scaffolding of the wicker-work shelves should be substantial; and they should be from 15 to 18 inches apart. A separate small apartment should be allotted to the sickly worms. Immediately before each moulting, the appetite of the worms begins to flag; it ceases altogether at that period of cutaneous metamorphosis, but revives speedily after the skin is fairly cast, because the internal parts of the animal are thereby allowed freely to develop themselves. At the end of the second age, the worms are half an inch long; and should then be transferred from the small room in which they were first hatched, into the proper apartment where they are tobe brought to maturity and set to spin their balls. On occasion of changing their abode, they must be well cleansed from the litter, laid upon beds of fresh leaves, and supplied with an abundance of food every six hours in succession. In shifting their bed, a piece of network being laid over the wicker plates, and covered with leaves, the worms will creep up over them; when they may be transferred in a body upon the net. The litter, as well as the sickly worms, may thus be readily removed, without handling a single healthy one. After the third age, they may be fed with entire leaves; because they are now exceedingly voracious, and must not be subsequently stinted in their diet. The exposure of chloride of lime, spread thin upon plates, to the air of themagnanière, has been found useful in counteracting the tendency which sometimes appears of an epidemic disease among the silkworms, from the fetid exhalations of the dead and dying.When they have ceased to eat, either in the fourth or fifth age, agreeably to the variety of thebombyx, and when they display the spinning instinct by crawling up among the twigs of heath, &c., they are not long of beginning to construct their cocoons, by throwing the thread in different directions, so as to form the floss, filoselle, or outer open network, which constitutes thebourreor silk for carding and spinning.The cocoons destined for filature, must not be allowed to remain for many days with the worms alive within them; for should the chrysalis have leisure to grow mature or come out, the filaments at one end would be cut through, and thus lose almost all their value. It is therefore necessary to extinguish the life of the animal by heat, which is done either by exposing the cocoons for a few days to sunshine, by placing them in a hot oven, or in the steam of boiling water. A heat of 202° F. is sufficient for effecting this purpose, and it may be best administered by plunging tin cases filled with the cocoons into water heated to that pitch.80 pounds French (88 Eng.) of cocoons, are the average produce from one ounce of eggs, or 100 from one ounce and a quarter; but M. Folzer of Alsace obtained no less than 165 pounds. The silk obtained from a cocoon is from 750 to 1150 feet long. The varnish by which the coils are glued slightly together, is soluble in warm water.The silk husbandry, as it may be called, is completed in France within six weeks from the end of April, and thus affords the most rapid of agricultural returns, requiring merely the advance of a little capital for the purchase of the leaf. In buying up cocoons, and in the filature, indeed, capital may be often laid out to great advantage. The most hazardous period in the process of breeding the worms, is at the third and fourth moulting; for upon the 6th day of the third age, and the seventh day of the fourth, they in general eat nothing at all. On the first day of the fourth age, the worms proceeding from one ounce of eggs will, according to Bonafons, consume upon an average twenty-three pounds and a quarter of mulberry leaves; on the first of the fifth age, they will consume forty-two pounds; and on the sixth day of the same age, they acquire their maximum voracity, devouring no less than 223 pounds. From this date their appetite continually decreases, till on the tenth day of this age they consume only fifty-six pounds. The space which they occupy upon the wicker tables, being at their birth only nine feet square, becomes eventually 239 feet. In general the more food they consume, the more silk will they produce.A mulberry-tree is valued, in Provence, at from 6d.to 10d.; it is planted out of the nursery at four years of age; it is begun to be stripped in the fifth year, and affords an increasing crop of leaves till the twentieth. It yields from 1 cwt. to 30 cwt. of leaves, according to its magnitude and mode of cultivation. One ounce of silkworm eggs is worth in France about 21⁄2francs; it requires for its due development into cocoons about 15 cwt. of mulberry leaves, which cost upon an average 3 francs per cwt. in a favourable season. One ounce of eggs is calculated, as I have said, to produce from 80 to 100 pounds of cocoons, of the value of 1 fr. 52 centimes per pound, or 125 francs in whole. About 8 pounds of reeled raw silk, worth 18 francs a pound, are obtained from these 100 pounds of cocoons.There are three denominations of raw silk; viz., organzine,trame(shute or tram), and floss. Organzine serves for the warp of the best silk stuffs, and is considerably twisted; tram is made usually from inferior silk, and is very slightly twisted, in order that it may spread more, and cover better in the weft; floss, orbourre, consists of the shorter broken silk, which is carded and spun like cotton. Organzine and trame may contain from 3 to 30 twin filaments of the worm; the former possesses a double twist, the component filaments being first twisted in one direction, and the compound thread in the opposite; the latter receives merely a slender single twist. Each twin filament gradually diminishes in thickness and strength, from the surface of the cocoon, where the animal begins its work in a state of vigour, to the centre, where it finishes it, in a state of debility and exhaustion; because it can receive no food from the moment of its beginning to spin by spouting forth its silky substance. The winder is attentive to this progressive attenuation, and introduces the commencement of some cocoons to compensate for thetermination of others. The quality of raw silk depends, therefore, very much upon the skill and care bestowed upon its filature. The softest and purest water should be used in the cocoon kettle.The quality of the raw silk is determined by first winding off 400 ells of it, equal to 475 metres, round a drum one ell in circumference, and then weighing that length. The weight is expressed in grains, 24 of which constitute one denier; 24 deniers constitute one ounce; and 16 ounces make one pound,poids de marc. This is the Lyons rule for valuing silk. The weight of a thread of raw silk 400 ells long, is two grains and a half, when five twin filaments have been reeled and associated together.Raw silk is so absorbent of moisture, that it may be increased ten per cent. in weight by this means. This property has led to falsifications; which are detected by enclosing weighed portions of the suspected silk in a wire-cloth cage, and exposing it to a stove-heat of about 78° F. for 24 hours, with a current of air. The loss of weight which it thereby undergoes, demonstrates the amount of the fraud. There is an office in Lyons called theCondition, where this assay is made, and by the report of which the silk is bought and sold. The law in France requires, that all the silk tried by theConditionmust be worked up into fabrics in that country.In the Journal of the Asiatic Society of Bengal, for January, 1837, there are two very valuable papers upon silkworms; the first, upon those of Assam, by Mr. Thomas Hugon, stationed at Nowgong; the second by Dr. Heifer, upon those which are indigenous to India. Besides theBombyx mori, the Doctor enumerates the following seven species, formerly unknown:—1. The wild silkworm of the central provinces, a moth not larger than theBombyx mori. 2. The Joree silkworm of Assam,Bombyx religiosæ, which spins a cocoon of a fine filament, with much lustre. It lives upon the pipul tree (Ficus religiosa), which abounds in India, and ought therefore to be turned to account in breeding this valuable moth. 3.Saturnia silhetica, which inhabits the cassia mountains in Silhet and Dacca, where its large cocoons are spun into silk. 4. A still largerSaturnia, one of the greatest moths in existence, measuring ten inches from the one end of the wing to the other; observed by Mr. Grant, inChirra Punjee. 5.Saturnia paphia, or the Tusseh silkworm, is the most common of the native species, and furnishes the cloth usually worn by Europeans in India. It has not hitherto been domesticated, but millions of its cocoons are annually collected in the jungles, and brought to the silk factories near Calcutta and Bhagelpur. It feeds most commonly on the hair-tree (Zizyphus jujuba), but it prefers theTerminalia alata, or Assam tree, and theBombax heptaphyllum. It is calledKoutkuri mooga, in Assam. 6. AnotherSaturnia, from the neighbourhood of Comercolly. 7.Saturnia assamensis, with a cocoon of a yellow-brown colour, different from all others, calledmooga, in Assam; which, although it can be reared in houses, thrives best in the open air upon trees, of which seven different kinds afford it food. TheMazankoory mooga, which feeds on the Adakoory tree, produces a fine silk, which is nearly white, and fetches 50 per cent. more than the fawn-coloured. The trees of the first year’s growth produce by far the most valuable cocoons. The mooga which inhabits the soom-tree, is found principally in the forests of the plains, and in the villages. The tree grows to a large size, and yields three crops of leaves in the year. The silk is of a light fawn colour, and ranks next in value to the Mazankoory. There are generally five breeds of mooga worms in the year; 1. in January and February; 2. in May and June; 3. in June and July; 4. in August and September; 5. in October and November; the first and last being the most valuable.The Assamese select for breeding, such cocoons only as have been begun to be formed in the largest number on the same day, usually the second or third after the commencement; those which contain males being distinguishable by a more pointed end. They are put in a closed basket suspended from the roof; the moths, as they come forth, having room to move about, after a day, the females (known only by their large body) are taken out, and tied to small wisps of thatching-straw, selected always from over the hearth, its darkened colour being thought more acceptable to the insect. If out of a batch, there should be but few males, the wisps with the females tied to them are exposed outside at night; and the males thrown away in the neighbourhood find their way to them. These wisps are hung upon a string tied across the roof, to keep them from vermin. The eggs laid after the first three days are said to produce weak worms. The wisps are taken out morning and evening, and exposed to the sunshine, and in ten days after being laid, a few of them are hatched. The wisps being then hung up to the tree, the young worms find their way to the leaves. The ants, whose bite is fatal to the worm in its early stages, are destroyed by rubbing the trunk of the tree with molasses, and tying dead fish and toads to it, to attract these rapacious insects in large numbers, when they are destroyed with fire; a process which needs to be repeated several times. The ground under the trees is also well cleared, to render it easy to pick up and replace the worms which fall down. They are prevented from coming tothe ground by tying fresh plantain-leaves round the trunk, over whose slippery surface they cannot crawl; and they are transferred from exhausted trees to fresh ones, on bamboo platters tied to long poles. The worms require to be constantly watched and protected from the depredations of both day and night birds, as well as rats and other vermin. During their moultings, they remain on the branches; but when about beginning to spin, they come down the trunk, and being stopped by the plantain-leaves, are there collected in baskets, which are afterwards put under bunches of dry leaves, suspended from the roof, into which the worms crawl, and form their cocoons—several being clustered together: this accident, due to the practice of crowding the worms together, which is most injudicious, rendering it impossible to wind off their silk in continuous threads, as in the filatures of Italy, France, and even Bengal. The silk is, therefore, spun like flax, instead of being unwound in single filaments. After four days the proper cocoons are selected for the next breed, and the rest are uncoiled. The total duration of a breed varies from 60 to 70 days; divided into the following periods:—Four moultings, with one day’s illness attending each20From fourth moulting to beginning of cocoon10In the cocoon 20, as a moth 6, hatching of eggs 103666On being tapped with the finger, the body renders a hollow sound; the quality of which shows whether they have come down for want of leaves on the tree, or from their having ceased feeding.As the chrysalis is not soon killed by exposure to the sun, the cocoons are put on stages, covered up with leaves, and exposed to the hot air from grass burned under them; they are next boiled for about an hour in a solution of the potash, made from incinerated rice-stalks; then taken out, and laid on cloth folded over them to keep them warm. The floss being removed by hand, they are then thrown into a basin of hot water to be unwound; which is done in a very rude and wasteful way.The plantations for the mooga silkworm in Lower Assam, amount to 5000 acres, besides what the forests contain; and yield 1500 maunds of 84 lbs. each per annum. Upper Assam is more productive.The cocoon of theKoutkuri moogais of the size of a fowl’s egg. It is a wild species, and affords filaments much valued for fishing-lines. SeeSilkworm Gut.8. TheArrindy, orEriaworm, and moth, is reared over a great part of Hindustan, but entirely within doors. It is fed principally on theHera, orPalma christileaves, and gives sometimes 12 broods of spun silk in the course of a year. It affords a fibre which looks rough at first; but when woven, becomes soft and silky, after repeated washings. The poorest people are clothed with stuff made of it, which is so durable as to descend from mother to daughter. The cocoons are put in a closed basket, and hung up in the house, out of reach of rats and insects. When the moths come forth, they are allowed to move about in the basket for twenty-four hours; after which the females are tied to long reeds or canes, twenty or twenty-five to each, and these are hung up in the house. The eggs that are laid the first three days, amounting to about 200, alone are kept; they are tied up in a cloth, and suspended to the roof till a few begin to hatch. These eggs are white, and of the size of turnip-seed. When a few of the worms are hatched, the cloths are put on small bamboo platters hung up in the house, in which they are fed with tender leaves. After the second moulting, they are removed to bunches of leaves suspended above the ground, beneath which a mat is laid to receive them when they fall. When they cease to feed, they are thrown into baskets full of dry leaves, among which they form their cocoons, two or three being often found joined together. Upon this injudicious practice I have already animadverted.9. TheSaturnia trifenestrata, has a yellow cocoon of a remarkably silky lustre. It lives on the soom-tree in Assam, but seems not to be much used.Silk filatureThe mechanism of the silk filature, as lately improved in France, is very ingenious.Figs.973.and974.exhibit it in plan and longitudinal view.ais an oblong copper basin containing water heated by a stove or by steam. It is usually divided by transverse partitions into several compartments, containing 20 cocoons, of which there are 5 in one group, as shown in the figure.b,b, are wires with hooks or eyelets at their ends, through which the filaments run, apart, and are kept from ravelling.c,c, the points where the filaments cross and rub each other, on purpose to clean their surfaces.d, is a spiral groove, working upon a pin point, to give the traverse motion alternately to right and left, whereby the thread is spread evenly over the surface of the reele.f,f, are the pulleys, which by means of cords transmit the rotatory movement of the cylinderd, to the reele.g, is a friction lever or tumbler, for lightening or slackening the endlesscord, in the act of starting or stopping the winding operation. Every apartment of a large filature contains usually a series of such reels as the above, all driven by one prime mover; each of which, however, may by means of the tumbling lever be stopped at pleasure. The reeler is careful to remove any slight adhesions, by the application of a brush in the progress of her work.The expense of reeling the excellent Cevennes silk is only 3 francs and 50 centimes per Alais pound; from 4 to 5 cocoons going to one thread. That pound is 92 hundredths of our avoirdupois pound. In Italy, the cost of reeling silk is much higher, being 7 Italian livres per pound, when 3 to 4 cocoons go to the formation of one thread; and 6 livres when there are from 4 to 5 cocoons. The first of these raw silks will have atitreof 20 to 24 deniers; the last, of 24 to 28. If 5 to 6 cocoons go to one thread, the titre will be from 26 to 32 deniers, according to the quality of the cocoons. The Italian livre is worth 71⁄2d.English. The woman employed at the kettle receives one livre and five sous per day; and the girl who turns the reel, gets thirteen sous a day; both receiving board and lodging in addition. In June, July, and August, they work 16 hours a day, and then they wind aruboor ten pounds weight of cocoons, which yield from 1-5th to 1-6th of silk, when the quality is good. The whole expenses amount to from 6 to 7 livres upon every ten pounds of cocoons; which is about 2s.8d.per English pound of raw silk.The raw silk, as imported into this country in hanks from the filatures, requires to be regularly wound upon bobbins, doubled, twisted, and reeled in our silk-mills. These processes are calledthrowingsilk, and their proprietors are called silkthrowsters; terms probably derived from the appearance of swinging or tossing which the silk threads exhibit during their rapid movements among the machinery of the mills.A representation of a French mill for throwing silk, is given in theDictionnaire Technologique, under the articleMoulinage de Soie. But it is a most awkward, operose, and defective piece of machinery, quite unworthy of being presented to my readers. It was in Manchester that throwing-mills received the grand improvement upon the antient Italian plan, which had been originally introduced into this country by Sir Thomas Lombe, and erected at Derby. That improvement is chiefly due to the eminent factory engineers, Messrs. Fairbairn and Lillie, who transferred to silk the elegant mechanism of the throstle, so well known in the cotton trade. Still, throughout the silk districts of France the throwing mills are generally small, not many of them turning off more than 1000 pounds of organzine per annum, and not involving 5000l.of capital. The average price of throwing organzine in that country, where the throwster is not answerable for loss, is 7 francs; of throwing trame, from 4 fr. to 5 fr. (per kilogramme?) Where the throwster is accountable for loss, the price is from 10 fr. to 11 fr. for organzine, and from 6 to 7 for trame. In Italy, throwing adds 3s.9d.to the price of raw silk, upon an average. I should imagine, from the perfection and speed of the silk-throwing machinery in this country, as about to be described, that the cost of converting a pound of raw silk either into organzine ortramemust be considerably under any of the above sums.SILK-THROWING MILL.Silk throwing millThe first process to which the silk is subjected, is winding the skeins, as imported, off upon bobbins. The mechanism which effects this winding off and on, is technically called theengine, or swift. The bobbins to which the silk is transferred, are woodencylinders, of such thickness as may not injure the silk by sudden flexure, and which may also receive a great length of thread without having their diameter materially increased, or their surface velocity changed.Fig.975.is an end view of the silk-throwing machine, orengine, in which the two large hexagonal reels, called swifts, are seen in section, as well as the table between them, to which the bobbins and impelling mechanism are attached. The skeins are put upon these reels, from which the silk is gradually unwound by the traction of the revolving bobbins. One principal object of attention, is to distribute the thread over the length of the bobbin-cylinder in a spiral or oblique direction, so that the end of the slender semi-transparent thread may be readily found when it breaks. As the bobbins revolve with uniform velocity, they would soon wind on too fast, were their diameters so small at first as to become greatly thicker when they are filled. They are therefore made large, are not covered thick, but are frequently changed. The motion is communicated to that end of the engine shown in the figure.The wooden tableA, shown here in cross section, is sometimes of great length, extending 20 feet, or more, according to the size of the apartment. Upon this the skeins are laid out. It is supported by the two strong slanting legsB,B, to which the bearings of the light reelCare made fast. These reels are calledswifts, apparently by the same etymological casuistry aslucus à non lucendo; for they turn with reluctant and irregular slowness; yet they do their work much quicker than any of the old apparatus, and in this respect may deserve their name. At every eighth or tenth leg there is a projecting horizontal pieceD, which carries at its end another horizontal bara, called the knee rail, at right angles to the former. This protects the slender reels or swifts from the knees of the operatives.These swifts have a strong wooden shaftb, with an iron axis passing longitudinally through it, round which they revolve, in brass bearings fixed near to the middle of the legsB. Upon the middle of the shaftb, a loose ring is hung, shown underc, infig.976., to which a light weightd, is suspended, for imparting friction to the reel, and thus preventing it from turning round, unless it be drawn with a gentle force, such as the traction of the thread in the act of winding upon the bobbin.SwiftsPulley mechanismFig.976.is a front view of the engine.B,B, are the legs, placed at their appropriate distances (scale 11⁄2inch to the foot);C,C, are the swifts. By comparingfigs.975.and976., the structure of the swifts will be fully understood. From the wooden shaftb, six slender wooden (or iron) spokese,e, proceed, at equal angles to each other; which are bound together by a cordf, near their free ends, upon the transverse linefof which cord, the silk thread is wound, in a hexagonal form; due tension being given to the circumferential cords, by sliding them out from the centre. Slender wooden rodsare set between each pair of spokes, to stay them, and to keep the cord tight.Eis one of the two horizontal shafts, placed upon each side of theengine, to which are affixed a number of light iron pulleysg,g(shown on a double scale infig.977.) These serve, by friction, to drive the bobbins which rest upon their peripheries.SpindleTo the tableA,fig.975., are screwed the light cast-iron slot-bearingsI,I, wherein the horizontal spindles or skewers rest, upon which the bobbins revolve. The spindles (seeF,fig.981.) carry upon one end a little wooden pulleyh, whereby they press and revolve upon the larger driving pulleysg, of the shaftE. These pulleys are calledstarsby our workmen. The other ends of the spindles, or skewers, are cut into screws, for attaching the swivel nutsi(fig.981.), by which the bobbinsK,K, are made fast to their respective spindles. Besides the slots, above described, in which the spindles rest when their friction pulleysh, are in contact with the moving starsg, there is another set of slots in the bearings, into which the ends of the spindles may be occasionally laid, so as to be above the line of contact of the rubbing periphery of the starg, in case the thread of any bobbin breaks. Whenever the girl has mended the thread, she replaces the bobbin-spindle in its deeper slot-bearings, thereby bringing its pulley once more into contact with the star, and causing it to revolve.Gis a long ruler or bar of wood, which is supported upon every eighth or twelfth legB,B. (The figure being, for convenience of the page, contracted in length, shows it at every sixth leg.) To the edge of that bar the smooth glass rodsk, are made fast, over which the threads glide from the swifts, intheir way to the bobbins.His the guide bar, which has a slow traverse or seesaw motion, sliding in slots at the top of the legsB, where they support the barsG. Upon the guide barH, the guide piecesl,l, are made fast. These consist of two narrow, thin, upright plates of iron, placed endwise together, their contiguous edges being smooth, parallel, and capable of approximation to any degree by a screw, so as to increase or diminish at pleasure the ordinary width of the vertical slit that separates them. Through this slit the silk thread must pass, and, if rough or knotty, will be either cleaned or broken; in the latter case, it is neatly mended by the attendant girl.Parts of machineThe motions of the various parts of theengineare given as follows. Upon the end of the machine, represented infig.975., there are attached to the shaftsE(fig.976.), the bevel wheels 1 and 2, which are set in motion by the bevel wheels 3 and 4, respectively. These latter wheels are fixed upon the shaftm,fig.975.mis moved by the main steam shaft which runs parallel to it, and at the same height, through the length of theengineapartment, so as to drive the whole range of the machines. 5 is a loose wheel or pulley upon the shaftm, working in geer with a wheel upon the steam shaft, and which may be connected by the clutchn, through the hand lever or geering rodo(figs.975.and976.), when the engine is to be set at work. 6 is a spur wheel upon the shaftm, by which the stud wheel 7, is driven, in order to give the traverse motion to the guide barH. This wheel is represented, with its appendages, in double size,figs.979. and 980., with its boss upon a studp, secured to the bracketq. In an eccentric hole of the same boss, another studr, revolves, upon which the little wheels, is fixed. This wheels, is in geer with a pinion cut upon the end of the fixed studp; and upon it is screwed the little crankt, whose collar is connected by two rodsu(figs.975.and976.), to a cross-piecev, which unites the two armsw, that are fixed upon the guide barH, on both sides of the machine. By the revolution of wheel 7, the wheelswill cause the pinion of the fixed studpto turn round. If that wheel bear to the pinion the proportion of 4 to 1, then the wheelswill make, at each revolution of the wheel 7, one-fourth of a revolution; whereby the cranktwill also rotate through one-fourth of a turn, so as to be brought nearer to the centre of the stud, and to draw the guide bar so much less to one side of its mean position. At the next revolution of wheel 7, the cranktwill move through another quadrant, and come still nearer to the central position, drawing the guide bars still less aside, and therefore causing the bobbins to wind on more thread in their middle than towards their ends. The contrary effect would ensue, were the guide bars moved by a single or simple crank. After four revolutions of the wheel 7, the cranktwill stand once more as shown infig.980., having moved the barHthrough the whole extent of its traverse. The bobbins, when filled, have the appearance represented infig.982.; the thread having been laid on the mall the time in diagonal lines, so as never to coincide with each other.Doublingis the next operation of the silk throwster. In this process, the threads of two or three of the bobbins, filled as above, are wound together in contact upon a single bobbin. An ingenious device is here employed to stop the winding-on the moment that one of these parallel threads happens to break. Instead of the swifts or reels, a creel is here mounted for receiving the bobbins from the former machine, two or three being placed in one line over each other, according as the threads are to be doubled or trebled. Though this machine is in many respects like theengine, it has some additional parts, whereby the bobbins are set at rest, as above mentioned, when one of the doubling threads gets broken.Doubling machineFig.983.is an end view, from which it will be perceived that the machine is, like the preceding, a double one, with two working sides.Doubling machineFig.984.is a front view of a considerable portion of the machine.Bobbin winderFig.985.shows part of a cross section, to explain minutely the mode of winding upon a single bobbin.Bobbin winderFig.986.is the plan of the parts shown infig.985.; these two figures being drawn to double the scale offigs.983.and984.A,A,figs.983.and984.are the end frames, connected at their tops by a wooden stretcher, orbar-beam,a, which extends through the whole length of the machine; this bar is shown also infigs.985.and986.B,B, are the creels upon each side of the machine, or bobbin bearers, resting upon wooden beams or boards, made fast to the arms or bracketsC, about the middle of the framesA.Ratchet wheelD,D, are two horizontal iron shafts, which pervade the whole machine, and carry a series of light movable pulleys, calledstars,c,c, (figs.985,986.) which serve to drive thebobbinsE,E, whose fixed pulleys rest upon their peripheries, and are therefore turned simply by friction. These bobbins are screwed by swivel nutse,e, upon spindles, as in the silk engine. Besides the small friction pulley or boss,d, seen best infig.986., by which they rest upon the star pulleysc,c, a little ratchet wheelf, is attached to the other end of each bobbin. This is also shown by itself atf, infig.987.The spindles with their bobbins revolve in two slot-bearingsF,F,fig.986., screwed to the bar-beama, which is supported by two or three intermediate upright frames, such asA′. The slot-bearingsF, have also a second slot, in which the spindle with the bobbin is laid at rest, out of contact of thestarwheel, while its broken thread is being mended.Gis the guide bar (to which the cleaner slit piecesg,g, are attached), for making the thread traverse to the right and the left, for its proper distribution over the surface of the bobbin. The guide bar of the doubling machine is moved with a slower traverse than in the engine; otherwise, in consequence of the different obliquities of the paths, the single threads would be readily broken,h,h, is a pair of smooth rods of iron or brass, placed parallel to each of the two sides of the machine, and made fast to the standardsH,H, which are screwed to brackets projecting from the framesA,A′. Over these rods the silk threads glide, in their passage to the guide wiresg,g, and the bobbinsE,E.I,I, is thelever boardupon each side of the machine, upon which the slight brass bearings or fulcrumsi,i, one for each bobbin in the creel, are made fast. This board bears thebalance-leverk,l, with thefullersn,n,n, which act as dexterous fingers, and stop the bobbin from winding-on the instant a thread may chance to break. The leversk,l, swing upon a fine wire axis, which passes through their propsi,i, their arms being shaped rectangularly, as shown atk,k′,fig.986.The arml, being heavier than the armk, naturally rests upon the ridge barm, of the lever boardI.n,n,n, are three wires, resting at one of their ends upon the axis of the fulcrumi,i, and having each of their other hooked ends suspended by one of the silk threads, as it passes over the front steel rodh, and underh′. These faller wires, or stop fingers, are guided truly in their up-and-down motions with the thread, by a cleaner-plateo, having a vertical slit in its middle. Hence, whenever any thread happens to break, in its way to a winding-on bobbinE, the wiren, which hung by its eyelet end to that thread, as it passed through between the steel rods in the line ofh,h′, falls upon the lighter arm of the balance leverk,l, weighs down that armk, consequently jerks up the arml, which pitches its tip or end into one of the three notches of the ratchet or catch wheelf(figs.986.and987.), fixed to the end of the bobbin. Thus its motion is instantaneously arrested, till the girl has had leisure to mend the thread, when she again hangs up the faller wiren, and restores the leverk,l, to its horizontal position. If, meanwhile, she took occasion to remove the winding bobbin out of the sunk slot-bearing, where pulleydtouches thestarwheelc, into the right-hand upper slot of repose, she must now shift it into its slot of rotation.The motions are given to the doubling machine in a very simple way. Upon the end of the framing, represented infig.983., the shaftsD,D, bear two spur wheels 1 and 2, which work into each other. To the wheel 1, is attached the bevel wheel 3, driven by another bevel wheel 4 (fig.984.), fixed to a shaft that extends the whole length of the apartment, and serves, therefore, to drive a whole range of machines. The wheel 4 may be put in geer with the shaft, by a clutch and geer-handle, as in the silkengine, and thereby it drives two shafts, by the one transmitting its movement to the other.The traverse motion of the guide barG, is effected as follows:—Upon one of the shaftsD, there is a bevel wheel 5, driving the bevel wheel 6, upon the top of the upright shaftp(fig.984., to the right of the middle); whence the motion is transmitted to the horizontal shaftq, below, by means of the bevel wheels 7 and 8. Upon this shaftq, there is a heart-wheelr, working against a roller which is fixed to the end of the levers, whose fulcrum is att,fig.983.The other end of the levers, is connected by two rods (shown by dotted lines infig.984.) to a brass piece which joins the armsu(fig.984.), of the guide barsG. To the same cross piece a cord is attached, which goes over a rollerv, and suspends a weightw, by means of which the levers, is pressed into contact with the heart-wheelr. The fulcrumt, of the levers, is a shaft which is turned somewhat eccentric, and has a very slow rotatory motion. Thus the guide bar, after each traverse, necessarily winds the silk in variable lines, to the side of the preceding threads.The motion is given to this shaft in the following way. Upon the horizontal shaftq, there is a bevel wheelg(figs.983.and984.), which drives the wheel 10 upon the shaftx; on whose upper end, the wormyworks in the wheel 11, made fast to the said eccentric shaftt; round which the levers, swings or oscillates, causing the guide bars to traverse.The spinning silk-mill.—The machine which twists the silk threads, either in their single or doubled state, is called the spinning mill. When the raw singles are first twisted in one direction, next doubled, and then twisted together in the opposite direction, an exceedingly wiry, compact thread, is produced, calledorganzine. In the spinning mill, either the singles or the doubled silk, while being unwound from one set of bobbins, and wound upon another set, is subjected to a regular twisting operation; in which process the thread is conducted as usual through guides, and coiled diagonally upon the bobbins by a proper mechanism.Spinning machineFig.988.exhibits an end view of the spinning mill; in which four working lines are shown; two tiers upon each side, one above the other. Some spinning mills havethree working tiers upon each side; but as the highest tier must be reached by a ladder or platform, this construction is considered by many to be injudicious.Spinning machineFig.989.is a front view, where, as in the former figure, the two working lines are shown.Details of machineFig.990.is a cross section of a part of the machine, to illustrate the construction and play of the working parts;figs.996,997.are other views offig.990.Details of machineFig.991.shows a single part of the machine, by which the bobbins are made to revolve.Figs.992.and993.show a different mode of giving the traverse to the guide bars, than that represented infig.990.BobbinsFigs.994.and995.show the shape of the full bobbins, produced by the action of these two different traverse motions.The upper part of the machine being exactly the same as the under part, it will be sufficient to explain the construction and operation of one of them.A,A, are the end upright frames or standards, between which are two or three intermediate standards, according to the length of the machine. They are all connected at their sides by beamsBandC, which extend the whole length of the machines.D,D, are the spindles, whose top bearingsa,a, are made fast to the beamsB, and their bottoms turn in hard brass steps, fixed to the barC. These two bars together arecalled, by the workmen, the spindle box. The standardsA,A, are bound with cross barsN,N.c,c, are the wharves or whorls, turned by a band from the horizontal tin cylinder in the lines ofE,E,fig.988., lying in the middle line between the two parallel rows of spindlesD,D.F,F, are the bobbins containing the untwisted doubled silk, which are simply pressed down upon the taper end of the spindles.d,d, are little flyers, or forked wings of wire, attached to washers of wood, which revolve loose upon the tops of the said bobbinsF, and round the spindles. One of the wings is sometimes bent upwards, to serve as a guide to the silk, as shown by dotted lines infig.990.e,e, are pieces of wood pressed upon the tops of the spindles, to prevent the flyers from starting off by the centrifugal force.G, are horizontal shafts bearing a number of little spur wheelsf,f.H, are slot-bearings, similar to those of the doubling-machine, which are fixed to the end and middle frames. In these slots, the light square cast-iron shafts or spindlesg,fig.989., are laid, on whose end the spur wheelhis cast; and when the shaftglies in the front slot of its bearing, it is in geer with the wheelf, upon the shaftG; but when it is laid in the back slot, it is out of geer, and at rest. SeeF,F,fig.986.Upon these little cast-iron shafts or spindlesg,fig.991., the bobbins or blocksI, are thrust, for receiving, by winding-on, the twisted or spun silk. These blocks are made of a large diameter, in order that the silk fibres may not be too much bent; and they are but slightly filled, at each successive charge, lest, by increasing their diameter too much, they should produce too rapid an increase in the rate of winding, with proportional diminution in the twist, and risk of stretching or tearing the silk. They are therefore the more frequently changed.K,K, are the guide bars, with the guidesi,i, through which the silk passes, being drawn by the revolving bobbinsI, and delivered or laid on by the flyersd,d, from the rotatory twisting-bobbinsF. The operation of the machine is therefore simple, and the motions are given to the parts in a manner equally so.Upon the shaft of the tin cylinder or drum, exterior to the frame, the usual fast and loose pulleys, or riggers,L,L′, are mounted, for driving the whole machine. These riggers are often called steam-pulleys by the workmen, from their being connected by bands with the steam-driven shaft of the factory. In order to allow the riggers upon the shafts of the upper and the under drums to be driven from the same pulley upon the main shaft, the axis of the under drum is prolonged atL,L, and supported at its end, directly from the floor, by an upright bearing. Upon the shafts of the tin cylinders there is also a fly-wheelM, to equalize the motion. Upon the other ends of these shafts, namely at the end of the spinning-mill, represented infig.988., the pinions 1 are fixed, which drive the wheels 3, by means of the intermediate or carrier wheel 2; called also the plate wheel, from its being hollowed somewhat like a trencher. 1, is called the change-pinion, because it is changed for another, of a different size and different number of teeth, when a change in the velocity of wheels 2 and 3 is to be made. To allow a greater or smaller pinion to be applied at 1, the wheel 2 is mounted upon a studk, which is movable in a slot concentric with the axis of the wheel 3. This slot is a branch from the cross barN. The smaller the change-pinion is, the nearer will the studkapproach to the vertical line joining the centres of wheels 1 and 3; and the more slowly will the plate wheel 2 be driven. To the spur wheel 3, a bevel wheel 4, is fixed, with which the other also revolves loose upon a stud. The bevel wheel 5, upon the shaftl, is driven by the bevel wheel 4; and it communicates motion, by the bevel wheels 6 and 7, to each of the horizontal shaftsG,G, extending along the upper and under tiers of the machine. At the left-hand side of the top part offig.988.the two wheels 6 and 7 are omitted, on purpose to show the bearings of the shaftG, as also the slot-bearings for carrying the shafts or skewers of the bobbins.If it be desired to communicate twist in the opposite direction to that which would be given by the actual arrangement of the wheels, it is necessary merely to transpose the carrier wheel 2, from its present position on the right hand of pinion 1, to the left of it, and to drive the tin cylinder by a crossed or close strap, instead of a straight or open one.The traverse motion of the guide is given here in a similar way to that of the engine, (fig.975.) Near one of the middle or cross-frames of the machine (seefig.990.) the wheelf, in geer with a spur wheelh, upon one of the block-shafts, drives also a spur wheelm, that revolves upon a stud, to which wheel is fixed a bevel wheeln, in geer with the bevel wheelo. To wheelo, the same mechanism is attached as was described underfigs.979. and 980., and which is here marked with the same letters.To the crank-knobr,fig.990., a rodx, is attached, which moves or traverses the guide bar belonging to that part of the machine; to each machine one such apparatus is fitted. Infigs.992.and993.another mode of traversing the guide bar is shown, which is generally used for the coarser qualities of silk. Near to one of the middle frames, one of the wheelsf, in geer with the spur wheelm, and the bevel wheeln, both revolving on one stud, gives motion also to the wheelo, fixed upon a shafta′, at whose other end the elliptical wheelb′is fixed, which drives a second elliptical wheelc′, in such a way that the larger diameter of the one plays in geer with the smaller diameter of the other; the teeth being so cut as to take into each other in all positions. The crank-pieced′is screwed upon the face of the wheelc′, at such a distance from its centre as may be necessary to give the desired length of traverse motion to the guide bar for laying the silk spirally upon the blocks. The purpose of the elliptical wheel is to modify the simple crank motion, which would wind on more silk at the ends of the bobbins than in their middle, and to effect an equality of winding-on over the whole surface of the blocks. Infig.993.the elliptical wheels are shown in front, to illustrate their mode of operating upon each other.Fig.994.is a block filled by the motion of the eccentric,fig.900.; andfig.995.is a block filled by the elliptical mechanism. As the length of the motions of the bar in the latter construction remains the same during the whole operation, the silk, as it is wound on the blocks, will slide over the edges, and thereby produce the flat ends of the barrel infig.995.The conical ends of the block (fig.994.) are produced by the continually shortened motions of the guide bar, as the stud approaches, in its sun-and-planet rotation, nearer to the general centre.Differential mechanismFigs.996,997.are two different views of the differential mechanism described underfig.990.The bent wirex,fig.990., is called the guider iron. It is attached at one end to the pivot of the sun-and-planet wheel-workt,s,o, and at the other to the guide barf,f,fig.989.The silk threads pass through the guides, as already explained. By the motion communicated to the guide bar (guider), the diamond pattern is produced, as shown infig.994.THE SILK AUTOMATIC REEL.In this machine, the silk is unwound from the blocks of the throwing-mill, and formed into hanks for the market. The blocks being of a large size, would be productive of much friction, if made to revolve upon skewers thrust through them, and would cause frequent breakage of the silk. They are, therefore, set with their axes upright upon a board, and the silk is drawn from their surface, just as the weft is from a cop in the shuttle. On this account the previous winding-on must be executed in a very regular manner; and preferably as represented infig.994.Automatic silk reelAutomatic silk reelFig.998.is a front view of the reel; little more than one-half of it being shown.Fig.999.is an end view. Here the steam-pulleys are omitted, for fear of obstructing the view of the more essential parts.A,A, are the two end framings, connected by mahogany stretchers, which form the tableB, for receiving the bobbinsC,C, which are sometimes weighted at top with a lump of lead, to prevent their tumbling.Dis the reel, consisting of four long laths of wood, which are fixed upon iron frames, attached to an octagonal wooden shaft. The arm which sustains one of these laths is capable of being bent inwards, by loosening a tightening hook, so as to permit the hanks, when finished, to be taken off, as in every common reel.The machine consists of two equal parts, coupled together ata, to facilitate the removal of the silk from either half of the reel; the attendant first lifting the one part, and then the other.Eis the guide bar, which by a traverse motion causes the silk to be wound on in a cross direction.bandcare the wire guides, anddare little levers lying upon the cloth-covered guide barE. The silk in its way from the block to the reel, passes under these levers, by which it is cleaned from loose fibres.On the other end of the shaft of the reel, the spur wheel 1 is fixed, which derives motion from wheel 2, attached to the shaft of the steam-pulleyF. Upon the same shaft there is a bevel wheel 3, which impels the wheel 4 upon the shafte; to whose end a plate is attached, to which the crankfis screwed, in such a way as to give the proper length of traverse motion to the guide barE, connected to that crank or eccentric stud by the jointed rodg. Upon the shaft of the steam-pulleysF, there is a worm or endless screw, to the left off,fig.999., which works in a wheel 5; attached to the short upright shafth(fig.998.). At the end ofh, there is another worm, which works in a wheel 6; at whose circumference there is a studi, which strikes once at every revolution against an arm attached to a bell, seen to the left ofG; thus announcing to the reel-tenter that a measured length of silk has been wound upon her reel.eis a rod or handle, by which the forkl, with the strap, may be moved upon the fast or loose pulley, so as to set on or arrest the motion at pleasure.Throwsters submit their silk to scouring and steaming processes. They soak thehanks, as imported, in lukewarm soap-water in a tub; but the bobbins of the twisted single silk from the spinning mill are enclosed within a wooden chest, and exposed to the opening action of steam for about ten minutes. They are then immersed in a cistern of warm water, from which they are transferred to the doubling frame.The wages of the workpeople in the silk-throwing mills of Italy are about one half of their wages in Manchester; but this difference is much more than counterbalanced by the protecting duty of 2s.10d.a pound upon thrown silk, and the superior machinery of our mills. In 1832, there was a power equal to 342 horses engaged in the silk-throwing mills of Manchester; and of about 100 in the mills of Derby. The power employed in the other silk mills of England and Scotland has not been recorded.There is a peculiar kind of silk calledmarabout, containing generally three threads, made from the white Novi raw silk. From its whiteness, it takes the most lively and delicate colours without the discharge of its gum. After being made into tram by the single twist upon the spinning mill, it is reeled into hanks, and sent to the dyer without further preparation. After being dyed, the throwster re-winds and re-twists it upon the spinning mill, in order to give it the whipcord hardness which constitutes the peculiar feature of marabout. The cost of the raw Novi silk is 19s.6d.a pound; of throwing it into tram, 2s.6d.; of dyeing, 2s.; of re-winding and re-twisting, after it has been dyed, about 5s.; of waste, 2s., or 10 per cent.; the total of which sum is 31s.; being the price of one pound of marabout in 1832.AnEstimateof the Annual Quantities ofSilkproduced or exported from the several Countries in the World, exhibiting also the Countries to which exported.Countries whenceexported.Quantities.Countries towhich exported.Quanti-ties.Italy exports34,000balesof225small lbs.Bales.France produces10,500-731⁄8kils., or-England28,000India and Bengal export9,5001281⁄2Vienna lbs.France22,000Persia7,500162lbs. EnglishPrussia7,600China4,000Russia6,400Asia Minor3,500Austria and Germany5,000Levant, Turkey, and Archipelago export3,500Switzerland5,000Spain1,500Total74,000bales.Total74,000Note.—These estimates exclude the silk manufactured in Italy.The declared value of the silk manufactures exported from the United Kingdom in 1836, was 917,822l.; and in 1837, only 494,569. The deficit in the last year was owing to the commercial crisis in the United States; which country took, the preceding year, our silk goods to the value of 524,301l.
SILK MANUFACTURE. (Fabrique de soie, Fr.;Seidenfabrik, Germ.) This may be divided into two branches: 1. the production of raw silk; 2. its filature and preparation in the mill, for the purposes of the weaver and other textile artisans. The threads, as spun by the silkworm, and wound up in its cocoon, are all twins, in consequence of the twin orifice in the nose of the insect through which they are projected. These two threads are laid parallel to each other, and are glued more or less evenly together by a kind of glossy varnish, which also envelopes them, constituting nearly 25 per cent. of their weight. Each ultimate filament measures about1⁄2000of an inch in average fine silk, and the pair measures of course fully1⁄1000of an inch. In the raw silk, as imported from Italy, France, China, &c., several of these twin filaments are slightly twisted and agglutinated to form one thread, called a single.
The specific gravity of silk is 1·300, water being 1·000. It is by far the most tenacious or the strongest of all textile fibres, a thread of it of a certain diameter being nearly three times stronger than a thread of flax, and twice stronger than hemp. Some varieties of silk are perfectly white, but the general colour in the native state is a golden yellow.
The production of silk was unknown in Europe till the sixth century, when two monks, who brought some eggs of the silkworm from China or India to Constantinople, were encouraged to breed the insect, and cultivate its cocoons, by the Emperor Justinian. Several silk manufactures were in consequence established in Athens, Thebes, and Corinth, not only for rearing the worm upon mulberry-leaves, but for unwinding its cocoons, for twisting their filaments into stronger threads, and weaving these into robes. The Venetians having then and long afterwards intimate commercial relations with the Greek empire, supplied the whole of western Europe with silk goods, and derived great riches from the trade.
About 1130, Roger II., king of Sicily, set up a silk manufacture at Palermo, and another in Calabria, conducted by artisans whom he had seized and carried off as prisoners of war in his expedition to the Holy Land. From these countries, the silk industry soon spread throughout Italy. It seems to have been introduced into Spain at a very early period, by the Moors, particularly in Murcia, Cordova, and Granada. The last town, indeed, possessed a flourishing silk trade when it was taken by Ferdinand in the 15th century. The French having been supplied with workmen from Milan, commenced, in 1521, the silk manufacture; but it was not till 1564 that they began successfully to produce the silk itself, when Traucat, a working gardener at Nismes, formed the first nursery of white mulberry-trees, and with such success, that in a few years he was enabled to propagate them over many of the southern provinces of France. Prior to this time, some French noblemen, on their return from the conquest of Naples, had introduced a few silkworms with the mulberry into Dauphiny; but the business had not prospered in their hands. The mulberry plantations were greatly encouraged by Henry IV.; and since then they have been the source of most beneficial employment to the French people. James I. was most solicitous to introduce the breeding of silkworms into England, and in a speech from the throne he earnestly recommended his subjects to plant mulberry-trees; but he totally failed in the project. This country does not seem to be well adapted for this species of husbandry, on account of the great prevalence of blighting east winds during the months of April and May, when the worms require a plentiful supply of mulberry-leaves. The manufacture of silk goods, however, made great progress during that king’s peaceful and pompous reign. In 1629 it had become so considerable in London, that the silk-throwsters of the city and suburbs were formed into a public corporation. So early as 1661 they employed 40,000 persons. The revocation of the edict of Nantes, in 1685, contributed in a remarkable manner to the increase of the English silk trade, by the influx of a large colony of skilful French weavers, who settled in Spitalfields. The great silk-throwing mill mounted at Derby, in 1719, also served to promote the extension of this branch of manufacture; for soonafterwards, in the year 1730, the English silk goods bore a higher price in Italy than those made by the Italians, according to the testimony of Keysler.
Till the year 1826, however, our silk manufactures in general laboured under very grievous fiscal burdens. Foreign organzine, or twisted raw silk, paid an import duty of 14s.71⁄2d.per pound; raw Bengal silk, 4s.; and that from other places, 5s.71⁄2d.Mr. Huskisson introduced a bill at that time, reducing the duty on organzine to 5s., and the duty on other raw silk to 3d.per pound. The total prohibition of the import of French manufactured silks, which gave rise to so much contraband trade, was also converted into a duty of 30 per cent.ad valorem. During the reign of the prohibitory system, when our silk weavers had no variety of patterns to imitate, and no adequate stimulus to excel, on account of the monopoly which they possessed in the home market, the inferiority of their productions was a subject of constant pride and congratulation among the Lyonnais; and accordingly the English could not stand their competition any where. At that time, the disadvantage on English silk goods, compared to French, was estimated in foreign markets at 40 per cent.; of late years it certainly does not exceed 20, notwithstanding the many peculiar facilities which France enjoys for this her favourite staple.
The silkworm, called by entomologistsPhalæna bombyx mori, is, like its kindred species, subject to four metamorphoses. The egg, fostered by the genial warmth of spring, sends forth a caterpillar, which, in its progressive enlargement, casts its skin either three or four times, according to the variety of the insect. Having acquired its full size in the course of 25 or 30 days, and ceasing to eat during the remainder of its life, it begins to discharge a viscid secretion, in the form of pulpy twin filaments, from its nose, which harden in the air. These threads are instinctively coiled into an ovoid nest round itself, called a cocoon, which serves as a defence against living enemies and changes of temperature. Here it soon changes into the chrysalis or nymph state, in which it lies swaddled, as it were, for about 15 or 20 days. Then it bursts its cearments, and comes forth furnished with appropriate wings, antennæ, and feet, for living in its new element, the atmosphere. The male and the female moths couple together at this time, and terminate their union by a speedy death, their whole existence being limited to two months. The cocoons are completely formed in the course of three or four days; the finest being reserved as seed worms. From these cocoons, after an interval of 18 or 20 days, the moth makes its appearance, perforating its tomb by knocking with its head against one end of the cocoon, after softening it with saliva, and thus rendering the filaments more easily torn asunder by its claws. Such moths or aurelias are collected and placed upon a piece of soft cloth, where they couple and lay their eggs.
The eggs, or grains as they are usually termed, are enveloped in a liquid which causes them to adhere to the piece of cloth or paper on which the female lays them. From this glue they are readily freed, by dipping them in cold water, and wiping them dry. They are best preserved in theovumstate at a temperature of about 55° F. If the heat of spring advances rapidly in April, it must not be suffered to act on the eggs, otherwise it might hatch the caterpillars long before the mulberry has sent forth its leaves to nourish them. Another reason for keeping back their incubation is, that they may be hatched together in large broods, and not by small numbers in succession. The eggs are made up into small packets, of an ounce, or somewhat more, which in the south of France are generally attached to the girdles of the women during the day, and placed under their pillows at night. They are, of course, carefully examined from time to time. In large establishments, they are placed in an appropriate stove-room, where they are exposed to a temperature gradually increased till it reaches the 86th degree of Fahrenheit’s scale, which term it must not exceed. Aided by this heat, nature completes her mysterious work of incubation in eight or ten days. The teeming eggs are now covered with a sheet of paper pierced with numerous holes, about one-twelfth of an inch in diameter. Through these apertures the new-hatched worms creep upwards instinctively, to get at the tender mulberry leaves strewed over the paper.
The nursery where the worms are reared, is called by the French amagnanière; it ought to be a well-aired chamber, free from damp, excess of cold or heat, rats and other vermin. It should be ventilated occasionally, to purify the atmosphere from the noisome emanations produced by the excrements of the caterpillars and the decayed leaves. The scaffolding of the wicker-work shelves should be substantial; and they should be from 15 to 18 inches apart. A separate small apartment should be allotted to the sickly worms. Immediately before each moulting, the appetite of the worms begins to flag; it ceases altogether at that period of cutaneous metamorphosis, but revives speedily after the skin is fairly cast, because the internal parts of the animal are thereby allowed freely to develop themselves. At the end of the second age, the worms are half an inch long; and should then be transferred from the small room in which they were first hatched, into the proper apartment where they are tobe brought to maturity and set to spin their balls. On occasion of changing their abode, they must be well cleansed from the litter, laid upon beds of fresh leaves, and supplied with an abundance of food every six hours in succession. In shifting their bed, a piece of network being laid over the wicker plates, and covered with leaves, the worms will creep up over them; when they may be transferred in a body upon the net. The litter, as well as the sickly worms, may thus be readily removed, without handling a single healthy one. After the third age, they may be fed with entire leaves; because they are now exceedingly voracious, and must not be subsequently stinted in their diet. The exposure of chloride of lime, spread thin upon plates, to the air of themagnanière, has been found useful in counteracting the tendency which sometimes appears of an epidemic disease among the silkworms, from the fetid exhalations of the dead and dying.
When they have ceased to eat, either in the fourth or fifth age, agreeably to the variety of thebombyx, and when they display the spinning instinct by crawling up among the twigs of heath, &c., they are not long of beginning to construct their cocoons, by throwing the thread in different directions, so as to form the floss, filoselle, or outer open network, which constitutes thebourreor silk for carding and spinning.
The cocoons destined for filature, must not be allowed to remain for many days with the worms alive within them; for should the chrysalis have leisure to grow mature or come out, the filaments at one end would be cut through, and thus lose almost all their value. It is therefore necessary to extinguish the life of the animal by heat, which is done either by exposing the cocoons for a few days to sunshine, by placing them in a hot oven, or in the steam of boiling water. A heat of 202° F. is sufficient for effecting this purpose, and it may be best administered by plunging tin cases filled with the cocoons into water heated to that pitch.
80 pounds French (88 Eng.) of cocoons, are the average produce from one ounce of eggs, or 100 from one ounce and a quarter; but M. Folzer of Alsace obtained no less than 165 pounds. The silk obtained from a cocoon is from 750 to 1150 feet long. The varnish by which the coils are glued slightly together, is soluble in warm water.
The silk husbandry, as it may be called, is completed in France within six weeks from the end of April, and thus affords the most rapid of agricultural returns, requiring merely the advance of a little capital for the purchase of the leaf. In buying up cocoons, and in the filature, indeed, capital may be often laid out to great advantage. The most hazardous period in the process of breeding the worms, is at the third and fourth moulting; for upon the 6th day of the third age, and the seventh day of the fourth, they in general eat nothing at all. On the first day of the fourth age, the worms proceeding from one ounce of eggs will, according to Bonafons, consume upon an average twenty-three pounds and a quarter of mulberry leaves; on the first of the fifth age, they will consume forty-two pounds; and on the sixth day of the same age, they acquire their maximum voracity, devouring no less than 223 pounds. From this date their appetite continually decreases, till on the tenth day of this age they consume only fifty-six pounds. The space which they occupy upon the wicker tables, being at their birth only nine feet square, becomes eventually 239 feet. In general the more food they consume, the more silk will they produce.
A mulberry-tree is valued, in Provence, at from 6d.to 10d.; it is planted out of the nursery at four years of age; it is begun to be stripped in the fifth year, and affords an increasing crop of leaves till the twentieth. It yields from 1 cwt. to 30 cwt. of leaves, according to its magnitude and mode of cultivation. One ounce of silkworm eggs is worth in France about 21⁄2francs; it requires for its due development into cocoons about 15 cwt. of mulberry leaves, which cost upon an average 3 francs per cwt. in a favourable season. One ounce of eggs is calculated, as I have said, to produce from 80 to 100 pounds of cocoons, of the value of 1 fr. 52 centimes per pound, or 125 francs in whole. About 8 pounds of reeled raw silk, worth 18 francs a pound, are obtained from these 100 pounds of cocoons.
There are three denominations of raw silk; viz., organzine,trame(shute or tram), and floss. Organzine serves for the warp of the best silk stuffs, and is considerably twisted; tram is made usually from inferior silk, and is very slightly twisted, in order that it may spread more, and cover better in the weft; floss, orbourre, consists of the shorter broken silk, which is carded and spun like cotton. Organzine and trame may contain from 3 to 30 twin filaments of the worm; the former possesses a double twist, the component filaments being first twisted in one direction, and the compound thread in the opposite; the latter receives merely a slender single twist. Each twin filament gradually diminishes in thickness and strength, from the surface of the cocoon, where the animal begins its work in a state of vigour, to the centre, where it finishes it, in a state of debility and exhaustion; because it can receive no food from the moment of its beginning to spin by spouting forth its silky substance. The winder is attentive to this progressive attenuation, and introduces the commencement of some cocoons to compensate for thetermination of others. The quality of raw silk depends, therefore, very much upon the skill and care bestowed upon its filature. The softest and purest water should be used in the cocoon kettle.
The quality of the raw silk is determined by first winding off 400 ells of it, equal to 475 metres, round a drum one ell in circumference, and then weighing that length. The weight is expressed in grains, 24 of which constitute one denier; 24 deniers constitute one ounce; and 16 ounces make one pound,poids de marc. This is the Lyons rule for valuing silk. The weight of a thread of raw silk 400 ells long, is two grains and a half, when five twin filaments have been reeled and associated together.
Raw silk is so absorbent of moisture, that it may be increased ten per cent. in weight by this means. This property has led to falsifications; which are detected by enclosing weighed portions of the suspected silk in a wire-cloth cage, and exposing it to a stove-heat of about 78° F. for 24 hours, with a current of air. The loss of weight which it thereby undergoes, demonstrates the amount of the fraud. There is an office in Lyons called theCondition, where this assay is made, and by the report of which the silk is bought and sold. The law in France requires, that all the silk tried by theConditionmust be worked up into fabrics in that country.
In the Journal of the Asiatic Society of Bengal, for January, 1837, there are two very valuable papers upon silkworms; the first, upon those of Assam, by Mr. Thomas Hugon, stationed at Nowgong; the second by Dr. Heifer, upon those which are indigenous to India. Besides theBombyx mori, the Doctor enumerates the following seven species, formerly unknown:—1. The wild silkworm of the central provinces, a moth not larger than theBombyx mori. 2. The Joree silkworm of Assam,Bombyx religiosæ, which spins a cocoon of a fine filament, with much lustre. It lives upon the pipul tree (Ficus religiosa), which abounds in India, and ought therefore to be turned to account in breeding this valuable moth. 3.Saturnia silhetica, which inhabits the cassia mountains in Silhet and Dacca, where its large cocoons are spun into silk. 4. A still largerSaturnia, one of the greatest moths in existence, measuring ten inches from the one end of the wing to the other; observed by Mr. Grant, inChirra Punjee. 5.Saturnia paphia, or the Tusseh silkworm, is the most common of the native species, and furnishes the cloth usually worn by Europeans in India. It has not hitherto been domesticated, but millions of its cocoons are annually collected in the jungles, and brought to the silk factories near Calcutta and Bhagelpur. It feeds most commonly on the hair-tree (Zizyphus jujuba), but it prefers theTerminalia alata, or Assam tree, and theBombax heptaphyllum. It is calledKoutkuri mooga, in Assam. 6. AnotherSaturnia, from the neighbourhood of Comercolly. 7.Saturnia assamensis, with a cocoon of a yellow-brown colour, different from all others, calledmooga, in Assam; which, although it can be reared in houses, thrives best in the open air upon trees, of which seven different kinds afford it food. TheMazankoory mooga, which feeds on the Adakoory tree, produces a fine silk, which is nearly white, and fetches 50 per cent. more than the fawn-coloured. The trees of the first year’s growth produce by far the most valuable cocoons. The mooga which inhabits the soom-tree, is found principally in the forests of the plains, and in the villages. The tree grows to a large size, and yields three crops of leaves in the year. The silk is of a light fawn colour, and ranks next in value to the Mazankoory. There are generally five breeds of mooga worms in the year; 1. in January and February; 2. in May and June; 3. in June and July; 4. in August and September; 5. in October and November; the first and last being the most valuable.
The Assamese select for breeding, such cocoons only as have been begun to be formed in the largest number on the same day, usually the second or third after the commencement; those which contain males being distinguishable by a more pointed end. They are put in a closed basket suspended from the roof; the moths, as they come forth, having room to move about, after a day, the females (known only by their large body) are taken out, and tied to small wisps of thatching-straw, selected always from over the hearth, its darkened colour being thought more acceptable to the insect. If out of a batch, there should be but few males, the wisps with the females tied to them are exposed outside at night; and the males thrown away in the neighbourhood find their way to them. These wisps are hung upon a string tied across the roof, to keep them from vermin. The eggs laid after the first three days are said to produce weak worms. The wisps are taken out morning and evening, and exposed to the sunshine, and in ten days after being laid, a few of them are hatched. The wisps being then hung up to the tree, the young worms find their way to the leaves. The ants, whose bite is fatal to the worm in its early stages, are destroyed by rubbing the trunk of the tree with molasses, and tying dead fish and toads to it, to attract these rapacious insects in large numbers, when they are destroyed with fire; a process which needs to be repeated several times. The ground under the trees is also well cleared, to render it easy to pick up and replace the worms which fall down. They are prevented from coming tothe ground by tying fresh plantain-leaves round the trunk, over whose slippery surface they cannot crawl; and they are transferred from exhausted trees to fresh ones, on bamboo platters tied to long poles. The worms require to be constantly watched and protected from the depredations of both day and night birds, as well as rats and other vermin. During their moultings, they remain on the branches; but when about beginning to spin, they come down the trunk, and being stopped by the plantain-leaves, are there collected in baskets, which are afterwards put under bunches of dry leaves, suspended from the roof, into which the worms crawl, and form their cocoons—several being clustered together: this accident, due to the practice of crowding the worms together, which is most injudicious, rendering it impossible to wind off their silk in continuous threads, as in the filatures of Italy, France, and even Bengal. The silk is, therefore, spun like flax, instead of being unwound in single filaments. After four days the proper cocoons are selected for the next breed, and the rest are uncoiled. The total duration of a breed varies from 60 to 70 days; divided into the following periods:—
On being tapped with the finger, the body renders a hollow sound; the quality of which shows whether they have come down for want of leaves on the tree, or from their having ceased feeding.
As the chrysalis is not soon killed by exposure to the sun, the cocoons are put on stages, covered up with leaves, and exposed to the hot air from grass burned under them; they are next boiled for about an hour in a solution of the potash, made from incinerated rice-stalks; then taken out, and laid on cloth folded over them to keep them warm. The floss being removed by hand, they are then thrown into a basin of hot water to be unwound; which is done in a very rude and wasteful way.
The plantations for the mooga silkworm in Lower Assam, amount to 5000 acres, besides what the forests contain; and yield 1500 maunds of 84 lbs. each per annum. Upper Assam is more productive.
The cocoon of theKoutkuri moogais of the size of a fowl’s egg. It is a wild species, and affords filaments much valued for fishing-lines. SeeSilkworm Gut.
8. TheArrindy, orEriaworm, and moth, is reared over a great part of Hindustan, but entirely within doors. It is fed principally on theHera, orPalma christileaves, and gives sometimes 12 broods of spun silk in the course of a year. It affords a fibre which looks rough at first; but when woven, becomes soft and silky, after repeated washings. The poorest people are clothed with stuff made of it, which is so durable as to descend from mother to daughter. The cocoons are put in a closed basket, and hung up in the house, out of reach of rats and insects. When the moths come forth, they are allowed to move about in the basket for twenty-four hours; after which the females are tied to long reeds or canes, twenty or twenty-five to each, and these are hung up in the house. The eggs that are laid the first three days, amounting to about 200, alone are kept; they are tied up in a cloth, and suspended to the roof till a few begin to hatch. These eggs are white, and of the size of turnip-seed. When a few of the worms are hatched, the cloths are put on small bamboo platters hung up in the house, in which they are fed with tender leaves. After the second moulting, they are removed to bunches of leaves suspended above the ground, beneath which a mat is laid to receive them when they fall. When they cease to feed, they are thrown into baskets full of dry leaves, among which they form their cocoons, two or three being often found joined together. Upon this injudicious practice I have already animadverted.
9. TheSaturnia trifenestrata, has a yellow cocoon of a remarkably silky lustre. It lives on the soom-tree in Assam, but seems not to be much used.
Silk filature
The mechanism of the silk filature, as lately improved in France, is very ingenious.Figs.973.and974.exhibit it in plan and longitudinal view.ais an oblong copper basin containing water heated by a stove or by steam. It is usually divided by transverse partitions into several compartments, containing 20 cocoons, of which there are 5 in one group, as shown in the figure.b,b, are wires with hooks or eyelets at their ends, through which the filaments run, apart, and are kept from ravelling.c,c, the points where the filaments cross and rub each other, on purpose to clean their surfaces.d, is a spiral groove, working upon a pin point, to give the traverse motion alternately to right and left, whereby the thread is spread evenly over the surface of the reele.f,f, are the pulleys, which by means of cords transmit the rotatory movement of the cylinderd, to the reele.g, is a friction lever or tumbler, for lightening or slackening the endlesscord, in the act of starting or stopping the winding operation. Every apartment of a large filature contains usually a series of such reels as the above, all driven by one prime mover; each of which, however, may by means of the tumbling lever be stopped at pleasure. The reeler is careful to remove any slight adhesions, by the application of a brush in the progress of her work.
The expense of reeling the excellent Cevennes silk is only 3 francs and 50 centimes per Alais pound; from 4 to 5 cocoons going to one thread. That pound is 92 hundredths of our avoirdupois pound. In Italy, the cost of reeling silk is much higher, being 7 Italian livres per pound, when 3 to 4 cocoons go to the formation of one thread; and 6 livres when there are from 4 to 5 cocoons. The first of these raw silks will have atitreof 20 to 24 deniers; the last, of 24 to 28. If 5 to 6 cocoons go to one thread, the titre will be from 26 to 32 deniers, according to the quality of the cocoons. The Italian livre is worth 71⁄2d.English. The woman employed at the kettle receives one livre and five sous per day; and the girl who turns the reel, gets thirteen sous a day; both receiving board and lodging in addition. In June, July, and August, they work 16 hours a day, and then they wind aruboor ten pounds weight of cocoons, which yield from 1-5th to 1-6th of silk, when the quality is good. The whole expenses amount to from 6 to 7 livres upon every ten pounds of cocoons; which is about 2s.8d.per English pound of raw silk.
The raw silk, as imported into this country in hanks from the filatures, requires to be regularly wound upon bobbins, doubled, twisted, and reeled in our silk-mills. These processes are calledthrowingsilk, and their proprietors are called silkthrowsters; terms probably derived from the appearance of swinging or tossing which the silk threads exhibit during their rapid movements among the machinery of the mills.
A representation of a French mill for throwing silk, is given in theDictionnaire Technologique, under the articleMoulinage de Soie. But it is a most awkward, operose, and defective piece of machinery, quite unworthy of being presented to my readers. It was in Manchester that throwing-mills received the grand improvement upon the antient Italian plan, which had been originally introduced into this country by Sir Thomas Lombe, and erected at Derby. That improvement is chiefly due to the eminent factory engineers, Messrs. Fairbairn and Lillie, who transferred to silk the elegant mechanism of the throstle, so well known in the cotton trade. Still, throughout the silk districts of France the throwing mills are generally small, not many of them turning off more than 1000 pounds of organzine per annum, and not involving 5000l.of capital. The average price of throwing organzine in that country, where the throwster is not answerable for loss, is 7 francs; of throwing trame, from 4 fr. to 5 fr. (per kilogramme?) Where the throwster is accountable for loss, the price is from 10 fr. to 11 fr. for organzine, and from 6 to 7 for trame. In Italy, throwing adds 3s.9d.to the price of raw silk, upon an average. I should imagine, from the perfection and speed of the silk-throwing machinery in this country, as about to be described, that the cost of converting a pound of raw silk either into organzine ortramemust be considerably under any of the above sums.
SILK-THROWING MILL.
Silk throwing mill
The first process to which the silk is subjected, is winding the skeins, as imported, off upon bobbins. The mechanism which effects this winding off and on, is technically called theengine, or swift. The bobbins to which the silk is transferred, are woodencylinders, of such thickness as may not injure the silk by sudden flexure, and which may also receive a great length of thread without having their diameter materially increased, or their surface velocity changed.Fig.975.is an end view of the silk-throwing machine, orengine, in which the two large hexagonal reels, called swifts, are seen in section, as well as the table between them, to which the bobbins and impelling mechanism are attached. The skeins are put upon these reels, from which the silk is gradually unwound by the traction of the revolving bobbins. One principal object of attention, is to distribute the thread over the length of the bobbin-cylinder in a spiral or oblique direction, so that the end of the slender semi-transparent thread may be readily found when it breaks. As the bobbins revolve with uniform velocity, they would soon wind on too fast, were their diameters so small at first as to become greatly thicker when they are filled. They are therefore made large, are not covered thick, but are frequently changed. The motion is communicated to that end of the engine shown in the figure.
The wooden tableA, shown here in cross section, is sometimes of great length, extending 20 feet, or more, according to the size of the apartment. Upon this the skeins are laid out. It is supported by the two strong slanting legsB,B, to which the bearings of the light reelCare made fast. These reels are calledswifts, apparently by the same etymological casuistry aslucus à non lucendo; for they turn with reluctant and irregular slowness; yet they do their work much quicker than any of the old apparatus, and in this respect may deserve their name. At every eighth or tenth leg there is a projecting horizontal pieceD, which carries at its end another horizontal bara, called the knee rail, at right angles to the former. This protects the slender reels or swifts from the knees of the operatives.
These swifts have a strong wooden shaftb, with an iron axis passing longitudinally through it, round which they revolve, in brass bearings fixed near to the middle of the legsB. Upon the middle of the shaftb, a loose ring is hung, shown underc, infig.976., to which a light weightd, is suspended, for imparting friction to the reel, and thus preventing it from turning round, unless it be drawn with a gentle force, such as the traction of the thread in the act of winding upon the bobbin.
Swifts
Pulley mechanism
Fig.976.is a front view of the engine.B,B, are the legs, placed at their appropriate distances (scale 11⁄2inch to the foot);C,C, are the swifts. By comparingfigs.975.and976., the structure of the swifts will be fully understood. From the wooden shaftb, six slender wooden (or iron) spokese,e, proceed, at equal angles to each other; which are bound together by a cordf, near their free ends, upon the transverse linefof which cord, the silk thread is wound, in a hexagonal form; due tension being given to the circumferential cords, by sliding them out from the centre. Slender wooden rodsare set between each pair of spokes, to stay them, and to keep the cord tight.Eis one of the two horizontal shafts, placed upon each side of theengine, to which are affixed a number of light iron pulleysg,g(shown on a double scale infig.977.) These serve, by friction, to drive the bobbins which rest upon their peripheries.
Spindle
To the tableA,fig.975., are screwed the light cast-iron slot-bearingsI,I, wherein the horizontal spindles or skewers rest, upon which the bobbins revolve. The spindles (seeF,fig.981.) carry upon one end a little wooden pulleyh, whereby they press and revolve upon the larger driving pulleysg, of the shaftE. These pulleys are calledstarsby our workmen. The other ends of the spindles, or skewers, are cut into screws, for attaching the swivel nutsi(fig.981.), by which the bobbinsK,K, are made fast to their respective spindles. Besides the slots, above described, in which the spindles rest when their friction pulleysh, are in contact with the moving starsg, there is another set of slots in the bearings, into which the ends of the spindles may be occasionally laid, so as to be above the line of contact of the rubbing periphery of the starg, in case the thread of any bobbin breaks. Whenever the girl has mended the thread, she replaces the bobbin-spindle in its deeper slot-bearings, thereby bringing its pulley once more into contact with the star, and causing it to revolve.
Gis a long ruler or bar of wood, which is supported upon every eighth or twelfth legB,B. (The figure being, for convenience of the page, contracted in length, shows it at every sixth leg.) To the edge of that bar the smooth glass rodsk, are made fast, over which the threads glide from the swifts, intheir way to the bobbins.His the guide bar, which has a slow traverse or seesaw motion, sliding in slots at the top of the legsB, where they support the barsG. Upon the guide barH, the guide piecesl,l, are made fast. These consist of two narrow, thin, upright plates of iron, placed endwise together, their contiguous edges being smooth, parallel, and capable of approximation to any degree by a screw, so as to increase or diminish at pleasure the ordinary width of the vertical slit that separates them. Through this slit the silk thread must pass, and, if rough or knotty, will be either cleaned or broken; in the latter case, it is neatly mended by the attendant girl.
Parts of machine
The motions of the various parts of theengineare given as follows. Upon the end of the machine, represented infig.975., there are attached to the shaftsE(fig.976.), the bevel wheels 1 and 2, which are set in motion by the bevel wheels 3 and 4, respectively. These latter wheels are fixed upon the shaftm,fig.975.mis moved by the main steam shaft which runs parallel to it, and at the same height, through the length of theengineapartment, so as to drive the whole range of the machines. 5 is a loose wheel or pulley upon the shaftm, working in geer with a wheel upon the steam shaft, and which may be connected by the clutchn, through the hand lever or geering rodo(figs.975.and976.), when the engine is to be set at work. 6 is a spur wheel upon the shaftm, by which the stud wheel 7, is driven, in order to give the traverse motion to the guide barH. This wheel is represented, with its appendages, in double size,figs.979. and 980., with its boss upon a studp, secured to the bracketq. In an eccentric hole of the same boss, another studr, revolves, upon which the little wheels, is fixed. This wheels, is in geer with a pinion cut upon the end of the fixed studp; and upon it is screwed the little crankt, whose collar is connected by two rodsu(figs.975.and976.), to a cross-piecev, which unites the two armsw, that are fixed upon the guide barH, on both sides of the machine. By the revolution of wheel 7, the wheelswill cause the pinion of the fixed studpto turn round. If that wheel bear to the pinion the proportion of 4 to 1, then the wheelswill make, at each revolution of the wheel 7, one-fourth of a revolution; whereby the cranktwill also rotate through one-fourth of a turn, so as to be brought nearer to the centre of the stud, and to draw the guide bar so much less to one side of its mean position. At the next revolution of wheel 7, the cranktwill move through another quadrant, and come still nearer to the central position, drawing the guide bars still less aside, and therefore causing the bobbins to wind on more thread in their middle than towards their ends. The contrary effect would ensue, were the guide bars moved by a single or simple crank. After four revolutions of the wheel 7, the cranktwill stand once more as shown infig.980., having moved the barHthrough the whole extent of its traverse. The bobbins, when filled, have the appearance represented infig.982.; the thread having been laid on the mall the time in diagonal lines, so as never to coincide with each other.
Doublingis the next operation of the silk throwster. In this process, the threads of two or three of the bobbins, filled as above, are wound together in contact upon a single bobbin. An ingenious device is here employed to stop the winding-on the moment that one of these parallel threads happens to break. Instead of the swifts or reels, a creel is here mounted for receiving the bobbins from the former machine, two or three being placed in one line over each other, according as the threads are to be doubled or trebled. Though this machine is in many respects like theengine, it has some additional parts, whereby the bobbins are set at rest, as above mentioned, when one of the doubling threads gets broken.
Doubling machine
Fig.983.is an end view, from which it will be perceived that the machine is, like the preceding, a double one, with two working sides.
Doubling machine
Fig.984.is a front view of a considerable portion of the machine.
Bobbin winder
Fig.985.shows part of a cross section, to explain minutely the mode of winding upon a single bobbin.
Bobbin winder
Fig.986.is the plan of the parts shown infig.985.; these two figures being drawn to double the scale offigs.983.and984.
A,A,figs.983.and984.are the end frames, connected at their tops by a wooden stretcher, orbar-beam,a, which extends through the whole length of the machine; this bar is shown also infigs.985.and986.
B,B, are the creels upon each side of the machine, or bobbin bearers, resting upon wooden beams or boards, made fast to the arms or bracketsC, about the middle of the framesA.
Ratchet wheel
D,D, are two horizontal iron shafts, which pervade the whole machine, and carry a series of light movable pulleys, calledstars,c,c, (figs.985,986.) which serve to drive thebobbinsE,E, whose fixed pulleys rest upon their peripheries, and are therefore turned simply by friction. These bobbins are screwed by swivel nutse,e, upon spindles, as in the silk engine. Besides the small friction pulley or boss,d, seen best infig.986., by which they rest upon the star pulleysc,c, a little ratchet wheelf, is attached to the other end of each bobbin. This is also shown by itself atf, infig.987.
The spindles with their bobbins revolve in two slot-bearingsF,F,fig.986., screwed to the bar-beama, which is supported by two or three intermediate upright frames, such asA′. The slot-bearingsF, have also a second slot, in which the spindle with the bobbin is laid at rest, out of contact of thestarwheel, while its broken thread is being mended.Gis the guide bar (to which the cleaner slit piecesg,g, are attached), for making the thread traverse to the right and the left, for its proper distribution over the surface of the bobbin. The guide bar of the doubling machine is moved with a slower traverse than in the engine; otherwise, in consequence of the different obliquities of the paths, the single threads would be readily broken,h,h, is a pair of smooth rods of iron or brass, placed parallel to each of the two sides of the machine, and made fast to the standardsH,H, which are screwed to brackets projecting from the framesA,A′. Over these rods the silk threads glide, in their passage to the guide wiresg,g, and the bobbinsE,E.
I,I, is thelever boardupon each side of the machine, upon which the slight brass bearings or fulcrumsi,i, one for each bobbin in the creel, are made fast. This board bears thebalance-leverk,l, with thefullersn,n,n, which act as dexterous fingers, and stop the bobbin from winding-on the instant a thread may chance to break. The leversk,l, swing upon a fine wire axis, which passes through their propsi,i, their arms being shaped rectangularly, as shown atk,k′,fig.986.The arml, being heavier than the armk, naturally rests upon the ridge barm, of the lever boardI.n,n,n, are three wires, resting at one of their ends upon the axis of the fulcrumi,i, and having each of their other hooked ends suspended by one of the silk threads, as it passes over the front steel rodh, and underh′. These faller wires, or stop fingers, are guided truly in their up-and-down motions with the thread, by a cleaner-plateo, having a vertical slit in its middle. Hence, whenever any thread happens to break, in its way to a winding-on bobbinE, the wiren, which hung by its eyelet end to that thread, as it passed through between the steel rods in the line ofh,h′, falls upon the lighter arm of the balance leverk,l, weighs down that armk, consequently jerks up the arml, which pitches its tip or end into one of the three notches of the ratchet or catch wheelf(figs.986.and987.), fixed to the end of the bobbin. Thus its motion is instantaneously arrested, till the girl has had leisure to mend the thread, when she again hangs up the faller wiren, and restores the leverk,l, to its horizontal position. If, meanwhile, she took occasion to remove the winding bobbin out of the sunk slot-bearing, where pulleydtouches thestarwheelc, into the right-hand upper slot of repose, she must now shift it into its slot of rotation.
The motions are given to the doubling machine in a very simple way. Upon the end of the framing, represented infig.983., the shaftsD,D, bear two spur wheels 1 and 2, which work into each other. To the wheel 1, is attached the bevel wheel 3, driven by another bevel wheel 4 (fig.984.), fixed to a shaft that extends the whole length of the apartment, and serves, therefore, to drive a whole range of machines. The wheel 4 may be put in geer with the shaft, by a clutch and geer-handle, as in the silkengine, and thereby it drives two shafts, by the one transmitting its movement to the other.
The traverse motion of the guide barG, is effected as follows:—Upon one of the shaftsD, there is a bevel wheel 5, driving the bevel wheel 6, upon the top of the upright shaftp(fig.984., to the right of the middle); whence the motion is transmitted to the horizontal shaftq, below, by means of the bevel wheels 7 and 8. Upon this shaftq, there is a heart-wheelr, working against a roller which is fixed to the end of the levers, whose fulcrum is att,fig.983.The other end of the levers, is connected by two rods (shown by dotted lines infig.984.) to a brass piece which joins the armsu(fig.984.), of the guide barsG. To the same cross piece a cord is attached, which goes over a rollerv, and suspends a weightw, by means of which the levers, is pressed into contact with the heart-wheelr. The fulcrumt, of the levers, is a shaft which is turned somewhat eccentric, and has a very slow rotatory motion. Thus the guide bar, after each traverse, necessarily winds the silk in variable lines, to the side of the preceding threads.
The motion is given to this shaft in the following way. Upon the horizontal shaftq, there is a bevel wheelg(figs.983.and984.), which drives the wheel 10 upon the shaftx; on whose upper end, the wormyworks in the wheel 11, made fast to the said eccentric shaftt; round which the levers, swings or oscillates, causing the guide bars to traverse.
The spinning silk-mill.—The machine which twists the silk threads, either in their single or doubled state, is called the spinning mill. When the raw singles are first twisted in one direction, next doubled, and then twisted together in the opposite direction, an exceedingly wiry, compact thread, is produced, calledorganzine. In the spinning mill, either the singles or the doubled silk, while being unwound from one set of bobbins, and wound upon another set, is subjected to a regular twisting operation; in which process the thread is conducted as usual through guides, and coiled diagonally upon the bobbins by a proper mechanism.
Spinning machine
Fig.988.exhibits an end view of the spinning mill; in which four working lines are shown; two tiers upon each side, one above the other. Some spinning mills havethree working tiers upon each side; but as the highest tier must be reached by a ladder or platform, this construction is considered by many to be injudicious.
Spinning machine
Fig.989.is a front view, where, as in the former figure, the two working lines are shown.
Details of machine
Fig.990.is a cross section of a part of the machine, to illustrate the construction and play of the working parts;figs.996,997.are other views offig.990.
Details of machine
Fig.991.shows a single part of the machine, by which the bobbins are made to revolve.
Figs.992.and993.show a different mode of giving the traverse to the guide bars, than that represented infig.990.
Bobbins
Figs.994.and995.show the shape of the full bobbins, produced by the action of these two different traverse motions.
The upper part of the machine being exactly the same as the under part, it will be sufficient to explain the construction and operation of one of them.
A,A, are the end upright frames or standards, between which are two or three intermediate standards, according to the length of the machine. They are all connected at their sides by beamsBandC, which extend the whole length of the machines.D,D, are the spindles, whose top bearingsa,a, are made fast to the beamsB, and their bottoms turn in hard brass steps, fixed to the barC. These two bars together arecalled, by the workmen, the spindle box. The standardsA,A, are bound with cross barsN,N.
c,c, are the wharves or whorls, turned by a band from the horizontal tin cylinder in the lines ofE,E,fig.988., lying in the middle line between the two parallel rows of spindlesD,D.F,F, are the bobbins containing the untwisted doubled silk, which are simply pressed down upon the taper end of the spindles.d,d, are little flyers, or forked wings of wire, attached to washers of wood, which revolve loose upon the tops of the said bobbinsF, and round the spindles. One of the wings is sometimes bent upwards, to serve as a guide to the silk, as shown by dotted lines infig.990.e,e, are pieces of wood pressed upon the tops of the spindles, to prevent the flyers from starting off by the centrifugal force.G, are horizontal shafts bearing a number of little spur wheelsf,f.H, are slot-bearings, similar to those of the doubling-machine, which are fixed to the end and middle frames. In these slots, the light square cast-iron shafts or spindlesg,fig.989., are laid, on whose end the spur wheelhis cast; and when the shaftglies in the front slot of its bearing, it is in geer with the wheelf, upon the shaftG; but when it is laid in the back slot, it is out of geer, and at rest. SeeF,F,fig.986.
Upon these little cast-iron shafts or spindlesg,fig.991., the bobbins or blocksI, are thrust, for receiving, by winding-on, the twisted or spun silk. These blocks are made of a large diameter, in order that the silk fibres may not be too much bent; and they are but slightly filled, at each successive charge, lest, by increasing their diameter too much, they should produce too rapid an increase in the rate of winding, with proportional diminution in the twist, and risk of stretching or tearing the silk. They are therefore the more frequently changed.K,K, are the guide bars, with the guidesi,i, through which the silk passes, being drawn by the revolving bobbinsI, and delivered or laid on by the flyersd,d, from the rotatory twisting-bobbinsF. The operation of the machine is therefore simple, and the motions are given to the parts in a manner equally so.
Upon the shaft of the tin cylinder or drum, exterior to the frame, the usual fast and loose pulleys, or riggers,L,L′, are mounted, for driving the whole machine. These riggers are often called steam-pulleys by the workmen, from their being connected by bands with the steam-driven shaft of the factory. In order to allow the riggers upon the shafts of the upper and the under drums to be driven from the same pulley upon the main shaft, the axis of the under drum is prolonged atL,L, and supported at its end, directly from the floor, by an upright bearing. Upon the shafts of the tin cylinders there is also a fly-wheelM, to equalize the motion. Upon the other ends of these shafts, namely at the end of the spinning-mill, represented infig.988., the pinions 1 are fixed, which drive the wheels 3, by means of the intermediate or carrier wheel 2; called also the plate wheel, from its being hollowed somewhat like a trencher. 1, is called the change-pinion, because it is changed for another, of a different size and different number of teeth, when a change in the velocity of wheels 2 and 3 is to be made. To allow a greater or smaller pinion to be applied at 1, the wheel 2 is mounted upon a studk, which is movable in a slot concentric with the axis of the wheel 3. This slot is a branch from the cross barN. The smaller the change-pinion is, the nearer will the studkapproach to the vertical line joining the centres of wheels 1 and 3; and the more slowly will the plate wheel 2 be driven. To the spur wheel 3, a bevel wheel 4, is fixed, with which the other also revolves loose upon a stud. The bevel wheel 5, upon the shaftl, is driven by the bevel wheel 4; and it communicates motion, by the bevel wheels 6 and 7, to each of the horizontal shaftsG,G, extending along the upper and under tiers of the machine. At the left-hand side of the top part offig.988.the two wheels 6 and 7 are omitted, on purpose to show the bearings of the shaftG, as also the slot-bearings for carrying the shafts or skewers of the bobbins.
If it be desired to communicate twist in the opposite direction to that which would be given by the actual arrangement of the wheels, it is necessary merely to transpose the carrier wheel 2, from its present position on the right hand of pinion 1, to the left of it, and to drive the tin cylinder by a crossed or close strap, instead of a straight or open one.
The traverse motion of the guide is given here in a similar way to that of the engine, (fig.975.) Near one of the middle or cross-frames of the machine (seefig.990.) the wheelf, in geer with a spur wheelh, upon one of the block-shafts, drives also a spur wheelm, that revolves upon a stud, to which wheel is fixed a bevel wheeln, in geer with the bevel wheelo. To wheelo, the same mechanism is attached as was described underfigs.979. and 980., and which is here marked with the same letters.
To the crank-knobr,fig.990., a rodx, is attached, which moves or traverses the guide bar belonging to that part of the machine; to each machine one such apparatus is fitted. Infigs.992.and993.another mode of traversing the guide bar is shown, which is generally used for the coarser qualities of silk. Near to one of the middle frames, one of the wheelsf, in geer with the spur wheelm, and the bevel wheeln, both revolving on one stud, gives motion also to the wheelo, fixed upon a shafta′, at whose other end the elliptical wheelb′is fixed, which drives a second elliptical wheelc′, in such a way that the larger diameter of the one plays in geer with the smaller diameter of the other; the teeth being so cut as to take into each other in all positions. The crank-pieced′is screwed upon the face of the wheelc′, at such a distance from its centre as may be necessary to give the desired length of traverse motion to the guide bar for laying the silk spirally upon the blocks. The purpose of the elliptical wheel is to modify the simple crank motion, which would wind on more silk at the ends of the bobbins than in their middle, and to effect an equality of winding-on over the whole surface of the blocks. Infig.993.the elliptical wheels are shown in front, to illustrate their mode of operating upon each other.Fig.994.is a block filled by the motion of the eccentric,fig.900.; andfig.995.is a block filled by the elliptical mechanism. As the length of the motions of the bar in the latter construction remains the same during the whole operation, the silk, as it is wound on the blocks, will slide over the edges, and thereby produce the flat ends of the barrel infig.995.The conical ends of the block (fig.994.) are produced by the continually shortened motions of the guide bar, as the stud approaches, in its sun-and-planet rotation, nearer to the general centre.
Differential mechanism
Figs.996,997.are two different views of the differential mechanism described underfig.990.
The bent wirex,fig.990., is called the guider iron. It is attached at one end to the pivot of the sun-and-planet wheel-workt,s,o, and at the other to the guide barf,f,fig.989.The silk threads pass through the guides, as already explained. By the motion communicated to the guide bar (guider), the diamond pattern is produced, as shown infig.994.
THE SILK AUTOMATIC REEL.
In this machine, the silk is unwound from the blocks of the throwing-mill, and formed into hanks for the market. The blocks being of a large size, would be productive of much friction, if made to revolve upon skewers thrust through them, and would cause frequent breakage of the silk. They are, therefore, set with their axes upright upon a board, and the silk is drawn from their surface, just as the weft is from a cop in the shuttle. On this account the previous winding-on must be executed in a very regular manner; and preferably as represented infig.994.
Automatic silk reel
Automatic silk reel
Fig.998.is a front view of the reel; little more than one-half of it being shown.Fig.999.is an end view. Here the steam-pulleys are omitted, for fear of obstructing the view of the more essential parts.A,A, are the two end framings, connected by mahogany stretchers, which form the tableB, for receiving the bobbinsC,C, which are sometimes weighted at top with a lump of lead, to prevent their tumbling.Dis the reel, consisting of four long laths of wood, which are fixed upon iron frames, attached to an octagonal wooden shaft. The arm which sustains one of these laths is capable of being bent inwards, by loosening a tightening hook, so as to permit the hanks, when finished, to be taken off, as in every common reel.
The machine consists of two equal parts, coupled together ata, to facilitate the removal of the silk from either half of the reel; the attendant first lifting the one part, and then the other.Eis the guide bar, which by a traverse motion causes the silk to be wound on in a cross direction.bandcare the wire guides, anddare little levers lying upon the cloth-covered guide barE. The silk in its way from the block to the reel, passes under these levers, by which it is cleaned from loose fibres.
On the other end of the shaft of the reel, the spur wheel 1 is fixed, which derives motion from wheel 2, attached to the shaft of the steam-pulleyF. Upon the same shaft there is a bevel wheel 3, which impels the wheel 4 upon the shafte; to whose end a plate is attached, to which the crankfis screwed, in such a way as to give the proper length of traverse motion to the guide barE, connected to that crank or eccentric stud by the jointed rodg. Upon the shaft of the steam-pulleysF, there is a worm or endless screw, to the left off,fig.999., which works in a wheel 5; attached to the short upright shafth(fig.998.). At the end ofh, there is another worm, which works in a wheel 6; at whose circumference there is a studi, which strikes once at every revolution against an arm attached to a bell, seen to the left ofG; thus announcing to the reel-tenter that a measured length of silk has been wound upon her reel.eis a rod or handle, by which the forkl, with the strap, may be moved upon the fast or loose pulley, so as to set on or arrest the motion at pleasure.
Throwsters submit their silk to scouring and steaming processes. They soak thehanks, as imported, in lukewarm soap-water in a tub; but the bobbins of the twisted single silk from the spinning mill are enclosed within a wooden chest, and exposed to the opening action of steam for about ten minutes. They are then immersed in a cistern of warm water, from which they are transferred to the doubling frame.
The wages of the workpeople in the silk-throwing mills of Italy are about one half of their wages in Manchester; but this difference is much more than counterbalanced by the protecting duty of 2s.10d.a pound upon thrown silk, and the superior machinery of our mills. In 1832, there was a power equal to 342 horses engaged in the silk-throwing mills of Manchester; and of about 100 in the mills of Derby. The power employed in the other silk mills of England and Scotland has not been recorded.
There is a peculiar kind of silk calledmarabout, containing generally three threads, made from the white Novi raw silk. From its whiteness, it takes the most lively and delicate colours without the discharge of its gum. After being made into tram by the single twist upon the spinning mill, it is reeled into hanks, and sent to the dyer without further preparation. After being dyed, the throwster re-winds and re-twists it upon the spinning mill, in order to give it the whipcord hardness which constitutes the peculiar feature of marabout. The cost of the raw Novi silk is 19s.6d.a pound; of throwing it into tram, 2s.6d.; of dyeing, 2s.; of re-winding and re-twisting, after it has been dyed, about 5s.; of waste, 2s., or 10 per cent.; the total of which sum is 31s.; being the price of one pound of marabout in 1832.
AnEstimateof the Annual Quantities ofSilkproduced or exported from the several Countries in the World, exhibiting also the Countries to which exported.
Note.—These estimates exclude the silk manufactured in Italy.
The declared value of the silk manufactures exported from the United Kingdom in 1836, was 917,822l.; and in 1837, only 494,569. The deficit in the last year was owing to the commercial crisis in the United States; which country took, the preceding year, our silk goods to the value of 524,301l.