Chapter VI: Special Jacquards and Harnesses (1)

CROSS-BORDER JACQUARDS

A difficulty has always existed in working cross borders on handkerchiefs, cloths, &c., so as to avoid having to shift or change the cards, and also to do without the expense of getting a complete set of cards cut for the whole cloth. It may be also that different patterns are required on the cloth, such as cross bands of small figures, and if, say, twenty cards would make a repeat of one figure, and it was required to weave, say, 100 repeats of this, and then change to, say, fifty repeats of some other figure, the same difficulty would arise as with cross borders. When there is only a short distance between the changes of pattern, it will generally be found more profitable, all things considered, to have the complete set of cards cut, so as to require no changing, particularly if the pattern will run for a length of time; but when the patterns or cloths are long, the cards become very expensive, and even if it would be desirable to get a complete set for the full cloth, it may be that there would not be space on the looms to hold them, over 15,000 cards being sometimes required to weave a complete tablecloth.

Many methods have been adopted to remedy the inconvenience and to save expense. A few of them will be given, but it must be left to manufacturers to judge whether they would prove an advantage to them or not.

For weaving cloths or curtains it is a common practice to have the cross-border cards and one repeat of the centre pattern cut. The card rack is made as in No. 2 (Fig. 99).

When either the border or centre cards are working, they are put into the hollow part of the rack or card frame, as at F, and the other set is hung on the flat rest of the frame, at either D or E. When a change is to be made, a card-shifter has to go up and change from one set to the other, lifting the set that had been working out of the hollow of the frame, and putting it back or forward on the rest D or E, and bringing the set which is to work down into the place of those removed. This, of course, is expensive, gives a great deal of trouble, and is severe on the cards; at the same time, in many cases it is found to answer as well as any method yet adopted, particularly where space is a consideration, and when two or more sets of cards are used, in case of two or more machines.

A better plan is to have a sliding-card frame, as shown in No. 1 of the same figure. A is the frame for the rollers over which the cards travel, B, B are two bars on which the card frame C, with the roller frame A attached, travels. The card frame is only shown in end view. Two of these must be for each set of cards, and the whole frame must be fastened together complete for all the cards required, so that it will all slide on the bars B, B. Suppose there are two machines working there must be four card racks; on two of these the centre cards are hung, and on the other two the border cards. Either set can be placed opposite the cylinders of the jacquard, and wrought as long as is required; then they must be taken off the cylinders, the card frame shifted till the other set of cards comes into their place, when they can be put on the cylinders and wrought over. This is a very good plan for working long cloths, but takes up a good deal of space, and for more than two machines might in many cases be unsuitable.

Another method is to have two sets of card irons, one above the other; the border cards are hung on the lower frame, and the centre cards on the upper one. The centre cards will work in the usual way, and when the border is to be wrought the cards for it are taken round the centre set, which, of course, are taken off the cylinder. The rollers must be made to shift so as to direct the cards properly into their respective frames; the top frame is smaller than the bottom one, and farther out from the machine. If hooks and eyes are sewn on the first and last cards of these sets, the weaver can hook them together when a fresh pattern is required, so that the one set will carry the other round the cylinder. Then, by drawing a cord, the rollers should change position so as to direct the falling cards into the proper frame. The card irons are of the usual shape, and the distance between the upper and lower ones may be regulated by circumstances.

Another simple method is to have the card frame made with a double curve in it, as shown in Fig. 100. One set of cards hang in each of these curves, as at A and B. The set in the curve A can be wrought over as long as required; then these cards can be taken off the cylinder and the set at B put over it. One thing must be observed: that the frame and rollers be so placed that the cards can be guided into the receptacle B, and to do this there must be a considerable fall for the cards, so that for a loom with a low framing this might not be feasible. Otherwise, it is a simple method of arranging two small lots of cards, and if one lot is much larger than the other, let A be a narrow curve, and the small lot of cards hang in it, which will lessen the slant of the cards falling to B.

Although such arrangements as the foregoing are required where there is much machinery used, it is evident that for frequent changes they would take up quite too much time. Several machines have been made for the purpose of changing from one set of cards to another without having to move the cards. The principle of these machines is to have two cylinders, one at each side; one set of cards is placed on one cylinder, and the other set on the other cylinder, so that by working one or other cylinder, as required, either border or centre may be woven. No. 1 (Fig. 101) shows a plan that was tried some time ago, but did not work satisfactorily. The needles passed through a needle board at each side of the machine, as at A and B, and had small spiral springs fastened on them inside the needle boards. The border cards could be put on the cylinder at A, and the centre cards on that at B. The cylinder at A could be wrought as a single-acting machine till a change of pattern was required; then the cylinder at B could be brought into action, and that at A remain stationary and clear of the needles. The heads of the hooks were made heart-shape, as shown, and the blades of the griffe could revolve into the position shown by the dotted lines, so as to suit the working of the cylinder at B; this was effected by the weaver pulling a cord. This machine was given up, as it was difficult to keep it in order.

Another method is shown at No. 2 (Fig. 101), where there are two griffes--one at F, and the other at G; one cylinder works at E, and the other at D. Only one set of springs is required on the needles--behind the needle board E--as the spring of the hooks is sufficient to act in the opposite direction. When the cylinder D is working the lower griffe is stationary, and when the cylinder E is working the upper griffe is stationary. The cylinders and griffes are brought into action as required by suitable mechanism. This machine has not been considered sufficiently successful to make it worthy of being persevered with.

The principle of Davenport & Crossley’s border jacquard is shown in Fig. 102. The upright hooks are as in an ordinary machine. Four of the needles are shown at _b_, and are made in the ordinary way, with the exception of the eyes in them for the small upright needles _d_ to pass through. These needles _d_ are connected with a set of horizontal ones, as shown at _a_, and act as levers between them and the needles _b_, the bars behind them serving as fulcrums; so that when the needles _a_ are pressed back by the cards, the needles _b_ are also drawn back through the medium of the uprights _d_. The cards least in action are put on the cylinder for the needles _a_, and the others act on the needles _b_. The cylinders can be brought in or out of action by the motion shown at A, B, C, D, E, F, G. A and B are the cylinders, working on swing motions; C A, D B, are connecting-rods for giving motion to the cylinders; either of these can be brought into action as required. G is a rocking lever carrying a stud on each end, which work in the slots C and D; these slots are shown at D^1 where the notch at one side of them will be clearly seen. When the stud on the bar G gets into this notch, the cylinder will be driven out and in, but when not in the notch the stud can slide along the slot, allowing the cylinder to remain stationary. By pulling the cord H either cylinder can be wrought as required through the connections shown, one of the connecting-rods being raised and the other lowered. F, E are the levers for driving the rocking bar G. This machine works very well, though the principle of its construction is not all that could be desired, and it requires a considerable space. It can be made a double-lift machine by having two hooks to each needle and two griffes as in the ordinary double-lift, single-cylinder machine.

The principle of Devoge’s border jacquard is shown in Fig. 103. C C is the rocking bar, for driving the cylinders, working on the centre D. It is driven by the levers F, G, and the connecting-rod E. The notches A and B fall over the studs on the cylinder frame, and can either be let down or raised, as required, by the cords K, L and the levers H, I. The machine is an ordinary double-cylinder one, and either griffe can be wrought to suit the cylinder that is in action. This machine can be used as an ordinary double-acting one, as a single-acting one raising both griffes together and bringing in both cylinders together, or as a border machine working one griffe and one cylinder at the same time.

Another method, similar to the above, is to have a double-cylinder machine with the cylinders wrought by the griffes, then have a stud on the crank-shaft wheel for raising one griffe, as for an ordinary single-acting jacquard, and the two connecting-rods from the griffes made so that either will work on it. A hook or catch can be put in any convenient place, so that when one connecting-rod is on the stud the other can be hooked out of the way. The rods can be made to slide on to the stud easily, and be fastened with a pin, so that the weaver can readily change from one to the other.

OPEN-SHED JACQUARDS

To obviate the vibration of the harness as much as possible, as well as to economise the wear and tear of it and to minimise the friction on the warp threads, especially in weaving patterns requiring heavy lifts, such as warp-faced patterns, Messrs. Priestley & Co., of Bradford, patented an open-shed jacquard, the principle of which is shown in Fig. 104. It did not, however, prove successful, as the tacklers found some difficulty in working it.

The machine is an ordinary double-lift jacquard with one cylinder, and works in the ordinary way. The hooks are made as in Fig. 104, where it may be observed there is a turn or catch on the lower portion of the hook, at A. Above these catches is a set of bars, _b_, like a stationary griffe, and when the hooks are raised by the upper griffe, in the ordinary way, they spring over these lower bars and rest on them when the griffe begins to fall. All the hooks raised would thus remain up, were it not that the cylinder, pressing in for the second griffe (the machine being double-acting), which begins to rise as the upper one begins to fall, presses back those hooks that are not to be raised for the following shot, and as they are held by the griffe above, they spring back at the bottom, and, clearing the bars _b_, come down with the falling griffe. In this way the hooks, when once raised, remain up till pressed off by the card, so that in the case of working a warp stripe with an 8-leaf satin binding the hooks would only fall for every seventh pick.

Another machine has since been tried, but did not work satisfactorily. In this machine the lifting hooks are formed with loops or hooks, in addition to the top hooks. The hooks are lifted in the ordinary way by the griffes; and upper knives, made to reciprocate horizontally, catch the raised hooks and support them. By suitably timing the motions of the card cylinder the hooks may be kept up as long as required by being transferred from one set of knives to the other. The shape of the hooks and needles is shown in Fig. 105. The needles may be as at _b_ or _b^1_. This machine acts as an ordinary double-lift jacquard, but has only one set of needles, which pass through needle boards at each side of the machine, and are acted upon by two card cylinders. No springs are required, the hooks acting as springs to keep the needles in position. The cylinders are driven by a tappet, and can be held against the needles as long as required; one cylinder must press on them when the griffes are passing, so as to prevent those hooks which are descending from being taken up by the ascending griffe. There are two griffes; three of the knives of the one are shown at 1, 3, 5, and three of the other at 2, 4, 6. When these knives lift the hooks by the lower loops or hooks on them, they deposit them on to a set of knives, _a_, _a_, _a_, _a_, in an upper grid or grating, which has a lateral or horizontal motion.

The lower knives raise the tops of the hooks slightly above these upper knives, so as to clear them, and the upper grid is then moved sideways, taking the knives from under one set of heads of the hooks and placing them under another set. Each time the griffe rises all the hooks not acted upon by the cards will be deposited on the upper grating, and will be transferred from one knife to another at each lift, till the card acting upon the needles keeps them clear of the upper grating and allows them to fall with the descending griffe. In this machine the tugs or tail cords, as used with double-lift machines, are not required, the double hooks serving for two single ones. Other efforts have been made in this direction, but the plan of using small pulleys on the tail cords, between the pairs of hooks, to which the neck twines are hung, is the only one worth mention. The same principle will be found for working the shafts in Fig. 115, and is more suitable for a few shafts than for 400 to 600 hooks, or pairs of hooks.

THE VERDÔL JACQUARD

Everyone accustomed to work large patterns on jacquards, especially on power looms, must have found the inconvenience resulting from a large set of cards. The space taken up, the time and trouble required for changing them, to say nothing of the cost, have been sufficiently felt, but have hitherto had to be borne with as a matter of necessity.

For working fine tablecloths with from 150 to 180 picks per inch, or for curtains where from 3 to 6 cards are required for each weft line of the design, and when from 2 to 4 jacquards are used, the inconvenience and cost of a set of cards ranging from 10,000 to 50,000 are very considerable. The small jacquards described at Fig. 30 make a great saving in the space taken up by the cards, as well as in the quantity of card paper used; but it has been thought that a still greater saving could be effected.

M. Verdôl, of Paris, has for a length of time been endeavouring to perfect a system of substituting a continuous roll of perforated paper for the cards, and has succeeded in doing so, though it is doubtful if he will be so far successful as to supersede our present method of working. These machines were taken up by Benson’s Patent Jacquard Company, of Belfast, in the year 1876, but did not then give satisfaction, the greatest obstacle in the way being the effect of the atmosphere on the paper; and as the needles are very closely set together, it was found impracticable to keep the paper set so as to act correctly on them. This difficulty is now claimed to be overcome by having procured paper which is said to be less liable to be affected by the atmosphere than the brass plates of the machine. Several of these machines have been tried in Scotland, but it will take some time to prove them thoroughly and get the workmen accustomed to them, as they are much finer than the jacquards in general use.

The Verdôl machine consists of a small jacquard, the ordinary French make of machine, which is usually made with 440 and 880 hooks for the single and double machines respectively. In addition there is a frame or box attached to the front of the machine, against the needle board, containing another set of horizontal and vertical needles or wires, which act upon the ordinary needles of the jacquard, according as they are acted upon by the perforated paper. Fig. 106, Nos. 1, 2, and 3, shows the principle of the machine. B, B show the needles, and D, D the uprights or hooks of the ordinary jacquard; only four of each are given, but sixteen are used. N is the face-plate or needle board, and O is the clap-board used for bringing back the needles, which have no springs on them; but the hooks are turned up double, and the back or turned-up portion of them, coming against horizontal wires or bars, shown in section above the needles, acts as a spring to keep them steady. This portion of the machine is a complete jacquard of the ordinary French make. In addition to this there is the apparatus on which the perforated paper acts, and which communicates this action to the jacquard. It consists of a box or frame containing two sets of wires--one set horizontal, as A A, about 6 in. long, and terminated at one end by a small head, as shown separately at A^1, which are called hitting wires. The other set is vertical, as C C, of fine wire, having a loop on one end, by which they are suspended in a frame, and a loop in the centre, which passes round the horizontal wires. These are called the vertical needles or feelers; one of them is shown separately at C^1. The points or lower ends of these needles pass through a horizontal brass plate, G, called a guide-bar. The hitting wires pass through a guide-plate, M, placed so that their heads will come exactly against the points of the needles in the jacquard, as shown in the figure. The other ends of the hitting wires lie loosely in the loops of the vertical needles, C. Underneath the guide-bar G is the curved brass plate I, which is in lieu of a cylinder. Between the cylinder and the guide-bar G the perforated roll of paper I I passes; there is just sufficient room between them for it to pass freely through, as it is moved forward by the stud wheel K. The paper may pass from one cylinder or reel to another, or may hang in folds in the same way as cards usually hang. At the points of the hitting wires is a grid or pushing frame, H, with an iron angle-bar across above each row of wires, as shown in section in No. 1 at H. There is a clap-board above the small vertical needles, which is shown raised at E in No. 1, and down in No. 2; this is raised and lowered with these needles, and serves to bring them all down when raised. E^1 shows the way in which these needles are hung in the frame that supports them. When the machine is working the frame H has a horizontal traverse coming against the ends of the hitting wires when they are pressed up by the card on the cylinder, and, pressing them against the needles of the jacquard, push them back as an ordinary card cylinder would. It may be seen in No. 1 that two of the feelers are down and two are pressed up, as they would be if two holes were cut in the paper and two uncut; the two that are up raise the hitting wires connected with them, and it will be observed that this raises the points of the hitting wires so as to come against the angle-iron of the grid H when it is coming forward; whereas the two hitting wires that are not raised will pass through, and not be pushed back. This enables the card paper to act on the needles of the jacquard in the same way as if coming directly on them, as cards do. The cylinder has a slight vertical motion, rising about 1/8 in. The needles, when the cylinder is down, do not pass through the plate G; it is perforated through and raised by the cylinder ascending. When the frame H is pressed forward the clap-board O is pressed back.

The card paper is of a special make, thin and tough, and is strengthened along both sides and in the centre by strips of paper pasted along it where the stud holes fall. No. 3 shows the motion by which the clap board E is raised and lowered by the sliding of the cranked bar F between the two studs 2. No. 4 shows the size and pitch of the holes in the hard paper. These are traced from the paper, and lie diagonally, two rows of 8 making one row of 16 hooks in the jacquard.

These machines are working in large numbers in France, and appear to give more satisfaction there than here, partly because they are better known, and the French workmen are better adapted to handle the small parts belonging to them. A coarser machine is more suited for the ordinary workmen to be found in the factories of this country. But it is strange if a machine of a pitch about half-way between the French jacquards and ours would not be better than either; not taking up so much room as ours, and not so minute as the French. However, in many cases the machines we have in use are none too large to give sufficient latitude for the errors often found cropping up in work, none of which should occur, of course, though they often do, through carelessness or otherwise. For instance, the card cylinder may be a little off the pitch, and the cards may be affected by damp, or may not be correctly cut to suit the cylinder; the points of the needles may be a little bent by the cylinder, or by the carelessness of the weaver when turning back her cards, and the cylinder may not be set quite fair for the needles. Mr. McMurdo, of Manchester, has made a very nice machine of the same pitch as the French ones, with 1,296 hooks, 16 row cards. It works as a double-acting machine with two cylinders and two griffes, but only one set of needles acting on the two sets of hooks. Two of the hooks are shown in Fig. 107; each needle clasps two hooks and passes through a needle board at each side of the machine. There is no spring on the needle, the hooks forming the spring, the tops of the hooks coming against the cross-rods at A A. Otherwise, this machine works in the usual way, and is very compact where a large number of hooks are required in a small space.

The card-cutting machine used for the French system of work is a very elaborate contrivance, being more like a jacquard loom than any of our card-cutting machines, at least in so far as the harness is concerned. The principle of it is seen in Fig. 108. a shows the set of cords by which the punches are wrought. The method of preparing the pattern to attach to these cords has been referred to before, but will be repeated again further on. These cords pass over the pulleys B and down through a reed to the lingoes C, which keep them in tension. Another set of cords pass from these over the pulleys D and down to the punches F. When any of the cords at A are drawn the punches connected with them are dropped, as raising the lingoes lets the cords pass over the pulleys D. When a punch is let fall, it is caught by one of the angle-irons of the grid G, which is pressed forwards when a card is to be cut. The card paper is on the roller JH, and passes down in front of the punches at I, which, when pressed forward, punch the paper between them and the block K. Any punches that are held up pass through the grid over the angle-iron bars. Only four punches are given, but sixteen are used in the machine; they are here drawn out of scale to show them more clearly. This portion constitutes the cutting machine; it is worked by two persons, one behind, to draw the cords, and another in front, to punch the paper by depressing a treadle each time a draw is made. In addition to cutting from the pattern the paper can be cut from other sets of cards, as in a repeating machine--cut either on the English or French system. N is the French machine, and a set of cards can be put on it and copied, the cords O acting on the punches; English-cut cards can be put on the machine at L and copied, the cords M acting on the punches. Of course, when one portion of the machine is working, the other parts remain idle, and it might be better to have them separate if much work is wanted.

The pattern is prepared for this machine by hand, working one repeat of it as follows:--The design, painted on point paper, is placed on a frame in an upright position, and over each line on it is stretched a vertical cord, which is taken as warp. The picker then takes a bobbin of weft and inserts it under every cord that passes over a painted dot on the first weft line of the pattern, keeping it in front of all the cords that pass over blank spaces, just in the same order as a shuttle would pass through if the shed were to be opened by a jacquard. When this is done the next line of the design paper is picked similarly, and so on, till a complete repeat of the design is loosely woven with cords, which are made of well-twisted harness twine. This process is somewhat similar to reading the pattern for the draw loom, _which see_. For coloured work a shot would require to be worked in for each colour on any weft line, the same as it is to be woven. When this is prepared, it is taken to the cutting machine and the warp tied to the cords A, the weft showing the warp ends to be drawn for each card.

HALF HARNESS AND MUSLIN HARNESSES

So far we have been speaking entirely of ‘full-harness’ work. Though the principle of mounting is much the same in all classes of harnesses, there are certain deviations peculiar to each.

One drawback to the full harness is the amount of machinery required to give a large extent of pattern, an upright hook and a needle being required for each thread in one repeat of the pattern. In a half harness only half the amount of machinery is required on the same fineness of cloth to give an equal extent of pattern; but it is only for a few classes of goods that this method of working is suitable, leno curtains and muslins being the principal. Leno curtains will be mentioned under gauzework, as they are wrought with a gauze mounting, but on the half-harness principle. Figured muslin curtains, with a plain ground and coloured flowering, are called ‘crêtes,’ or ‘crête curtains’; these are now generally wrought in a full harness. Figured muslins are much of the same class of cloth, but are not figured with colour and tint for the half harness, known as the ‘common spotting harness,’ or ‘book harness.’ For working them the harness is mounted in the ordinary manner, but only half as many cords are required for it as there are threads of warp. Only half of the warp is drawn into the harness, the other half--every alternate end--passing through it, and being drawn into a plain leaf of heddles, which is hung close in front of the harness. In fine work two leaves of heddles may be used as one, to prevent crowding.

The ground of the cloth is a plain texture, and was formerly wrought by having two leaves of long-eyed heddles in front of the harness, into which all the warp was drawn, this probably being more convenient for the hand-loom weaver; and besides, a more even plain ground can be made with the heddles than with the harness and one leaf of heddles. Two shots of ground, or fine weft, are given to one shot of figuring, or coarse weft, usually cotton rove; but to avoid using a pick-and-pick loom when working by power, the coarse shot may be made by throwing two finer ones into the same shed. In power looms the ground is wrought by raising the plain leaf of heddles and all the harness alternately, and the figuring shed is formed by drawing the harness with a card acting on the machine. The pattern is painted solid, without any twilling or binding on either ground or flower, so that the figuring shot will be in a plain shed for the flower, but will be loose or unbound over the ground, and is afterwards cut off in a cropping machine.

The plain shed, into which the thick weft is thrown, must also contain the shot of thin weft thrown in either before or after it, according as the figuring shed follows the plain shed made by raising the harness or the heddles; for supposing the heddle shaft to be raised and a ground shot thrown in, then the shed reversed by raising the harness and another ground shot thrown in, then the figure shed formed by raising 50 or 100 hooks of the harness, this opens portion of the last shed, and the figure weft will be thrown in along with the last shot of ground. When both wefts are white this is of but little consequence, but when using coloured wefts for the figure the ground weft would be liable to show along with them and injure the pattern. This was originally overcome by adopting the ‘paper harness’ from the shaft mounting for weaving paper spots. In this mounting two sets of shafts and two harnesses are used, one behind the other. Half of the warp--all the odd numbers of threads--was drawn on the back harness, and the other half--all the even numbers--on the front harness; this would be sufficient to make the cloth, but a pair of leaves of long-eyed heddles were used for working the ground, acting as pressers. On this method of working, a ground and a figuring shot are thrown in alternately, as either half of the warp can be raised by the harness for the figuring shed, and a richer spot is thus given; but still, the rove or figuring shot would fall into the same shed as the ground shot, which may be seen by examining the two spots given in Fig. 109, A being wrought on the common spot or half-harness mounting, and B on the paper-spot mounting. The grey shots are the ground, and the black ones the figure. However, in the paper-spot mounting it is not necessary to throw the rove into a plain shed; any suitable twill may be used for binding the figure, and will give a much richer effect on one side of the cloth than plain, and tie down the ground shot, which will go into a plain shed.

This principle of mounting is now done away with, as it has no advantage over the ordinary full-harness mounting, which can also have a pair of presser leaves of heddles in front for working the ground, if desired; but they are unnecessary in a power loom, except when a very level ground is required.

A twilled or flushed figure may be formed with the common half harness, but only having half the warp for binding causes it to be loose and ragged round the edges.

To work a large pattern, perhaps the most economical way, at least in the hand loom, is to use a pressure harness with two threads in the mail, and with four presser heddle leaves in front. The number of leaves regulates the twill on the figure. The cloth may be woven pick-and-pick, ground and figure, or 2 picks ground to 1 of figure. When the harness is drawn for the figure all the heddles must be sunk but one leaf, and sinking the two front and two back leaves alternately, raising the back ones when the front ones are sunk, and _vice versa_, will form plain cloth with the draft 1, 2, 3, and 4 over the leaves. A 4-leaf twilled figure can be made with this mounting, but still it will not have the advantage of the full harness, in which the figure can be varied in twill, and bound round the edges.

SPLIT HARNESS

The term ‘split harness’ is sometimes applied to the pressure harness when wrought with two threads in the mail, this constituting a splitful of warp, so that each cord of the harness controls a splitful of warp; but this is only the finest description of pressure harness.

The split harness, or ‘shaft monture,’ was invented in the silk district of Bethnal Green, shortly after the introduction of the jacquard, for weaving rich silks which have about 400 threads of warp per inch, but much less weft--perhaps about one-fifth of that number of threads. The harness is wrought with the ordinary jacquard, but there are two mails and lingoes attached to each neck cord, as shown in Fig. 110. A, A are the neck twines, B is the cumber board, and D the mails. If this mounting were wrought with the jacquard only, it would produce the same effect upon the cloth as if two threads were drawn into each mail of an ordinary harness. This would, of course, take away the fine appearance of the cloth. To avoid this a set of shafts, C, C, are passed through loops in the twine above the mails, and are attached to a set of hooks in front of the jacquard, or at each side of it, or may be wrought by a separate dobby. Twenty-four shafts are mostly used, and are usually flat enamelled iron bars. These shafts are for working the ground of the cloth, and can raise each row of mails separately, as shown at No. 1 leash, thus splitting the pairs of threads that are connected with each hook of the jacquard. One or more of these shafts, according to the texture required for the ground, are raised at the same time that the jacquard draws the figuring shed. No ground texture is put on the pattern for the cards, but the figure must be twilled, or have the binding marks cut on the cards for it. The binding of the figure will be in pairs of threads--that is, two threads of warp must sink together under a weft shot, though on the design these two threads will appear as one, as they are wrought by the same hook of the machine. On account of the number of warp threads, rising and sinking in pairs will not much affect the appearance of the figure; though it must be coarser than if the threads were bound separately, and will also have a rougher or more ragged outline; but to get a large figure with so much warp would necessitate a great amount of machinery if the threads were drawn into separate mails with one to each cord of the harness.

This method of working is surpassed by the twilling machines now in use (see Twilling Jacquards), though they are more intricate, and would not suit well for a hand loom, as they are heavy to draw.

PRESSURE HARNESS

This is the old draw-loom system of working, and, old as it is, is still in use on our modern hand and power looms on the finest description of damasks, and is not likely to be surpassed for making a good piece of cloth. Much firmer than a harness, and producing the largest possible pattern with the least possible cards, mounting, and machinery it took up its position in the days of the drawboy, and has held its own, with the aid of the jacquard, against all the inventions of modern times. The principal advantage of this system of working is that a much larger pattern can be produced with the same quantity of cards, mounting, and machinery, than by any other means; but the pattern wrought by a pressure harness will not compare with one wrought by a full harness for fineness of outline or detail. When weaving large tablecloths with 100 or 120 threads of warp per inch, and from 50 to 72, or even 90 in. in the single pattern--that is, when the pattern is all, or nearly all, single--the amount of machinery that would be required to work it on a full harness could not be crowded on a loom, the French system being the only one by which it might be attempted; and even then the difficulty of keeping the machinery and cards in perfect working order would be very great, not to mention the cost of mounting, patterns, cards, &c. The quantity of harness and machinery is reduced in a pressure harness by drawing two or more warp threads into each mail in the harness. Suppose we take 60 in. of cloth with 100 threads per inch = 6,000 threads, and allow 3 threads to each mail in the harness, or each hook of the jacquard, 2,000 hooks, or four 500 jacquards, would be required to work the pattern. As many as six 600 jacquards are sometimes required on this description of work when very fine; but three or four 500 or 600 machines are more commonly used on either hand or power looms. To work one of these finest patterns in a full harness 10,800 hooks would be required--say, six 600 machines with 3 threads to each mail = 10,800; and almost double this number of cards, even with working them backwards and forwards, would be necessary.

In early times, when the drawboy took the place of the jacquard, 6, 8, or 10 threads were put to each mail, or went to what would now be one hook of the jacquard; and patterns were not usually so extensive as they are now, so that the cords of the harness were greatly reduced in number, but with a proportionately coarser effect of pattern. The difference between a pattern wrought with a full harness and one wrought with the pressure or any of the twilling harnesses, is that the outline is clear and defined in the full harness, and the detail and points of the figures can be turned on a single thread, whereas in the others the edges of the figures will be jagged or in steps, and the points must turn on whatever number of threads are lifted together. The pattern on the cloth must therefore have somewhat of the rough, square effect of the design on point paper, though, of course, reduced in size, but will be worse in this respect--viz. that whereas the edges of the figure on the point paper are clear and well defined, on the cloth they are not so, the rough edges to some extent blending the figure into the ground, and not giving the clean, sharp effect of a full-harness pattern. Shaded effects are also coarse on a pressure harness, but can be made effective if broadly treated. Cloth with 100 or 120 threads per inch does very well to have three threads to the mail, and from 80 to 100 threads per inch suits very well for two to the mail. Any coarser set than 80 threads per inch requires to be woven in a full harness to produce good work, and for superior work nothing less than 100 threads per inch should have two threads to the mail, though 80 per inch does very well.

When several threads are put to the mail, it is also usual to put several picks to each card. The fewer picks, the finer will be the pattern; but a good method of regulating this is to make the checks formed on the cloth square, a little more or less according to the fineness of the pattern required. Thus, if the cloth is wefted square, or a little over that--say, 100 warp by 100 to 110 weft threads per inch--paint the design on, say, 8 × 8 or 8 × 9 paper, and give as many shots to the cards as there are threads in the mail. If the cloth is to be wefted one-half over square (100 × 150) the same pattern will still do, but with half as many more shots to the card than there are threads in the mail. If there are two threads in the mail there will be three picks to the card, but if there are three threads to the mail there must be four picks to one card and five to the next one. This would be for a pattern on 8 × 8, or square paper. If painted on 8 × 9 paper, which would give an extra card to every eight, and if the weft must not be increased, then four or five picks must be taken off the number given to the eight cards and put to the ninth one, for four cards with four picks to each and four with five picks to each = 36 picks, and thirty-six picks put to nine cards would allow four picks to each. This would make the edges of the pattern a little finer; and if the design was painted on 8 × 10 paper it would be finer still, as there would be more cards to a given number of picks.

In this way any alteration required can be made on the number of picks per inch given to cloth woven on a pressure or twilling harness, without distorting the pattern by varying the number of picks given to each card to suit the shotting. Neither is it necessary to have the same number of threads in each mail; the warp might be mailed 2’s and 3’s or 3’s and 4’s, but the more regular they are, the better. If the fineness of the cloth requires to be altered, it may be woven in the same harness without any alteration by varying the number of threads in the mails. For instance, a warp of ninety threads per inch mailed 3’s and one with 120 threads per inch mailed 4’s would work in the same harness. Similarly, the same set of cards would suit for making different widths of cloth by making the harness narrower in the cumber board and altering the mailing so as to keep the cloth the same set, or it may be made a finer set and not alter the mailing. In either case the pattern would be reduced in size.

Fig. 111 shows a portion of a pressure-harness mounting which is similar to that of the draw loom. It is mounted in the same manner as described for full harness, only that the warp must be divided by the number of threads to be drawn into each mail in order to find the quantity of harness required. The kinds of mails used are shown at A and B, Fig. 111; it does not do to have more than two threads drawn into each eye of the mail, as they are liable to twist round each other; two will separate easily, but a greater number will not. Ordinary full-harness mails answer very well for a two-thread harness. The mails are levelled in the same position as for full-harness work, viz. about 1-1/2 in. below the level of the back and front beams for hand-loom work, and a little lower for power looms. The lingoes are heavier than those required for a full harness; the weight depends upon the strength of the yarn and the number of threads in the mail; 10 to 12 to 1 lb. are used in power looms for linen damask with two threads in the mail, having about eighty to one hundred threads of warp per inch. For hand looms they are usually made of lead, thicker and shorter than the wire lingoes, and called ‘leads’; 11 to 15 per lb. suits for three- or four-thread harnesses. Light cotton work, such as muslin curtains, only requires lingoes of about sixty or seventy to 1 lb. for hand looms, but from twenty-five to thirty per lb. are used in power looms for two-thread harnesses.

The principle of working the pressure harness is best explained by the diaper mounting shown in Fig. 2, where a back set of heddles takes the place of the harness, and a set of ground leaves of long-eyed heddles stands in front of the back ones. After the yarn is drawn into the harness or back mounting in the usual way, it must be drawn into the front or presser heddles, using, generally, a straight draught for a satin ground. If Figs. 2 and 111 are examined, it will be seen that when the shed is opened by the harness or back mounting, the heddles in front sink part of the raised warp and raise part of the sunk warp. The mounting raises all the warp of the figuring portion on each card or line of the design paper, and leaves down all the ground warp, so that it is necessary to have the heddles in front to bind the warp and weft, or form the texture of the cloth. For an 8-leaf satin eight shafts are required; one of these must be raised and another sunk for each shot, so as to raise the binding threads of the sunk warp and sink those of the raised warp, the harness forming the outline of the pattern, or raising the warp of it in a mass. The other six leaves of heddles stand in a middle position, and the long eyes allow the warp drawn by the harness to rise. When the machine is drawn it is held up till as many shots as are to be given to the card are thrown in, but the shed formed by the heddles must be changed for each shot. In working bars up the cloth one card would be sufficient, and when the machine is drawn it would be held so, and the cloth wrought with the heddles; of course, no machine would be required in this case, one leaf of heddles with the stripes of warp drawn into it would be sufficient for the back mounting. For dices two leaves of heddles would be sufficient for the back mounting, the warp of one dice to be drawn on one leaf, and that of the other on the other leaf; then one leaf would be raised and held up till one dice was wrought, when it would be lowered, and the other one raised and held up for the other dice. For fancy dices and diapers the plan of mounting in Fig. 2 is very suitable and simple, but for a variety of figuring or flowering the jacquard is necessary.

It will be seen that the presser heddles have three positions, viz. a sunk, a raised, and a middle position. The length of the eyes is to allow the harness to open the shed when the heddles are stationary, or in their middle position. They must be a little longer than is required to open the shed at the back leaf of the heddles; for a 2-in. shed a 2-1/4-in. to 2-1/2-in. eye is used. When the heddles are stationary the lower loop of the eye should be fully 1/8 in. under the sunk warp, and there should be the same clearance at the top when the shed is drawn; some allow more. The shed for a pressure harness is usually very small in front of the reed, and requires a very small shuttle to be used, from 1/2 in. to 1 in. deep being the usual sizes. The depth of the shed that can be made depends principally on the elasticity of the yarn. With a linen warp a very small shed can be made, as the yarn has but little elasticity, and if overstrained will hang slack. For it the distance between the harness and the back shaft of the front mounting should be 10 in. to 12 in., and there should be a stretch of 27 in. to 34 in. behind the harness. The draw of the harness may then be 3 in. to 3-1/2 in., and the shed at the back shaft will be 1-3/4 in. to 2 in.; this will allow a shuttle of 3/4 in. to 7/8 in. deep to be used. For hand looms the shed is about 1-1/4 in. at the back shaft, and a shuttle of 1/2 in. deep is employed. The shed must be made very clear and regular, and the smaller it can be kept, the better. With a good cotton warp 7 in. is a sufficient distance to have between the harness and heddles, and will admit of a larger shed being formed; but it is not desirable to have too large a shed, as there is a considerable strain on the yarn, and a small, clear shed is more satisfactory. This would be assisted by bringing the harness as close as possible to the heddles.

One drawback to this method of working is the distance which separates the harness from the fell of the cloth, or even from the reed; and if there is any obstruction to the warp rising or falling, such as roughness in the heddles or reed, or lumps on the yarn, it will not, unless very tight, fall into its proper place, and the shuttle may pass over or under it when it should not do so, giving a picked or darned effect to the cloth; slack threads may cause the same.

The warp must be kept as tight as possible, and all the threads should be at a uniform tension, the heddles straining each thread alike; the harness should be as close to the heddles as the yarn will permit it to be. The space occupied by the harness, heddles, and traverse of lay should be no greater than is necessary; then, with a small but clear shed satisfactory work can be produced. When drawing a warp into the harness, a boy or girl sits behind, and hands the threads to the drawer-in, who takes them into the mails with a wire hook, and then either hands them to a second drawer-in sitting in front of the heddles, to be drawn into them, or passes them over and under a pair of rods tied across the harness so as to form a lease as she draws them in; and when she has all drawn into the harness, she begins to draw them into the heddles, a straight draught being mostly used for a twill or satin.