The weaver sits on the seat M, (fig. 1) which hangs by pivots at its ends, that it may adapt itself to the ease of the weaver when lie sits upon it. It is lifted out when the weaver gets into the loom, and he puts it in again after him. He leans lightly against the cloth roll, B, and places his feet upon the treddles, D E. In his right band he holds the handle y (fig. 2) and by his left he lays hold of a bar, called the lay-cape, which crosses the batten, or lay, G G, and serves to support the upper edge of the reed, R. He commences the operation by pressing down one of the treddles with his foot : this depresses one half of the yarns of the warp, and raises the other, as before described : the shut tle is placed in one of the troughs, I, against the pecker, k, belonging to that trough : by drawing the handle of the pecker with a sudden jerk, he drives the pecker against the shuttle, and throws it across the warp upon the shuttle-race into the other trough, I, leaving the yarn of the woof which was wound on the bobbin after it. With his left he then pulls the lay towards him ; by means of the reed, the yarn of the woof, which before was lying loose between the warp, is driven up towards the cloth roll : the weaver now presses down his other foot, which reverses the operation, pulling down the heddle which was up before, and raising that which before was depressed : by the other pecker he now throws the shuttle' back again, leaving the woof after it be tween the yarns of the warp ; and, by drawing up the batten, beats. it close up to the thread before thrown. In this man ner the operation is continued until a few inches are woven ; it is then wound upon the cloth roll, by putting a short lever in to a hole made in the roll, and turning it round. A click, acting in the teeth of a aerated wheel, prevents the return of the roll. The yarn roll, A (fig. 1,) has at each end a cord wound round it. One end of this cord is tied to the frame of the loom, the other has a weight hung to it : this rope causes a friction, which prevents its turning (unless the yarn is drawn by the cloth beam,) and always preserves a proper degree of tendon in the yarn. T '1' (fig. 1) are two smooth sticks (cotton weavers have usually three) put between the yarns, to preserve the lease, and keep the threads, or yarns, from entangling. In cotton weaving, these sticks, or rods, are kept at an uniform distance from the Meddles, either by tying them together, or by a small cord with a hook at one end, which lays hold of the front rod, and a weight at the other, which hangs over the yarn beam. The cloth is kept ex tended during the operation of weaving, by means of two pieces of hard wood, with small sharp points in their ends, which lay hold of the edges, or selvages, of the cloth. These pieces are connected by a cord, passing obliquely through holes, or notches, in each piece. By this cord they can be lengthened or shortened, according to the breadth of the web. They are kept flat after the cloth is stretched by a small bar turning on a centre fixed in one of the pieces, with its longer end projecting closely over the edge of the other piece. These pieces of wood, thus formed, are called the temples. Silk-weavers usually stretch their cloth by means of two small sharp pointed hooks, fastened to the ends of two strings, with little weights at the other ends ; and the strings are made to pass over little pulleys in each side of the loom, at a suitable distance from the sel vages of the cloth.
In the treading of a web, most begin ners are apt to apply the weight, or tbrce, of the foot much too suddenly. The bad consequences attending this mistake are particularly felt in weaving fine or weak cotton yarn. In weaving, as in every other branch of mechanics, the resist ance, or re-action, is always nearly as great as the moving power, or force, which it is necessary to apply. From this it fol lows, that the body of the warp must sus tain a stress, nearly equal to the force with which the weaver's foot is applied to the treddle. Besides this, every indivi dual thread is subjected to all the fric tion, occasioned by the beadles, and splits of the reed, between which the threads pass, and with which they are generally in contact when rising and sinking. But the art of spinning has not been as yet, and probably never can be, brought to such a degree of perfection, as to make every thread capable of bearing its pro portion of this stress equally. It is con
firmed both by mathematical demonstra tion, and by practical experience, that when any body is to be moved with in creased velocity, it is necessary to exert greater powers to move it ; and as the re sistance increases in proportion to the power, this sudden application of the pressure of the foot to the treddle, must cause a proportional increase of the stress upon the warp, and also of the friction. Now, as it is impossible to make every thread equally strong, and equally tight, those which are the weakest, or the tight est, must bear much more than their equal proportion of the stress. This causes them to be broken very frequently, and, even with the greatest attention, more time is lost in tying and replacing them, than would have been sufficient for weaving a very considerable quantity into cloth. But when the weaver, from inattention, continues the operation after one or more threads are broken, the con sequence is still worse. When a thread has been broken, it no longer retains its parallel situation to the rest, but crossing over or between those nearest to it, either breaks them also, or interrupts the passage of the shuttle : most frequently it does both.
In every kind of weaving, andespecially in thin wiry fabrics, much of the beauty of the cloth depends upon the woof being well stretched. But if the motion of the shuttle be too rapid, it is very apt to recoil, and thus to slacken the thread. It has also a greater tendency either to break the woof altogether, or to unwind it from the pirn in' bobbin, in doubles, which, if not picked out, destroy the regularity of the fabric. The woof of muslins and thin cotton goods is generally woven into the cloth in a wet state. This tends to lay the ends of the fibres of the cotton smooth 16, and parallel, and its effect is similar to that of dressing of the warp. The person 10, who winds the woof upon the pirii ought to be very careful that it be well built, so as to unwind freely. The best shape for those used in the fly-shuttle, in cotton weaving, is that of a cone ; and the thread ought to traverse freely, in the form of a_ spiral or screw, during the operation of winding.
The same wheel, used for winding the warp upon bobbins, is also fit for winding the weft. It only requires a spindle of a different shape, with a screw at one end, upon which the pirn is fixed. The wheel is so constructed, that the spindles may be easily shifted, to adapt it for either purpose.
That the fabric of the cloth may be uni form in thickness, it is necessary that the lay, or batten, should be brought forward with the same force every time. In the common operation of weaving, this regu larity must be acquired by practice. It is, however, of consequence to the weaver, to mount, or prepare, his loom in such a manner, that the range of the lay may be in proportion to the thickness of his cloth. As the lay swings, backward and forward, upon centres placed above, its motion is similar to that of a pendulum. Now the greater the arc, or range, through which the lay passes, the greater will be its ef fect, in driving home the weft strongly, and the thicker will be the fabric of the cloth, in so far as that depends upon the weft. For this reason, in weaving coarse and heavy goods, the heddles ought to be hung at a greater distance from the point where the weft is struck up, than would be proper in light work. The point, or rather line, where the last wrought shot of weft is struck up, is called by weavers the•ell. The pivots, upon which the lay vibrates ought, in general, to be exactly at equal distances from a line drawn per pendicular to the fell, and one drawn per pendicular to the heddles, and between these two lines. But as the fell is con stantly varying in its situation, during the operation, it will be proper to take the medium. This is the place where the fell will be, when a bore (i. e. as much as can be woven without drawing fresh yarn) is halfwrought up. From this, the following conclusion may also be drawn : The bores ought always to be short in weaving light goods ; for the less that the extremes vary from the medium, the more regular will be the arc, or swing, of the lay.