This hand loom was first improved, after the unsuccessful attempts of De Gennes in 1678, by Edmund Cartwright, who undertook in 1185 to counterfeit by mechanical means the three simple motions of weaving. He was a clergyman, with neither mechanical nor textile training, but his loom though cumbrous and awkward is essentially that now in use. Dr. Jeffrey, working independently, achieved about the same indifferent results. The first substan tial advance was made by Andrew Kinloch in 1793 and William Horrocks added his contri bution in overcoming some of the mechanical difficulties. But some minor inadequacies re maining, his loom was quickly superseded by the superior Richard Roberts loom built on the same principles but with greater mechanical skill. The simplest modern loom differs essen tially from the hand loom in that the warp yarn is no longer stretched direct from the yarn roll to the cloth beam, and these two parts are no longer placed at the same height from the base of the frame nor at so great a distance as before. The yarn runs upward from the warp-beam over the whip-roll, thence is carried through heald, heddle or (the American term) harness, and through the reed, and down from the latter to the cloth roll. The advantage of this arrangement is greater stability and a dis tinct saving in space, the depth of the loom being materially decreased. The ordinary power loom has no mechanical device for re newing the weft as it is used. The ordinary bobbin will run in a power loom for not more than four to six minutes — depending upon the fineness of the yarn. Then the loom must be stopped and a new bobbin put in. Two meth ods have been adopted to overcome this diffi culty: changing the shuttle, as in the Harri man loom, and changing the bobbin, as in the Northrop loom. In practice it has been found that at the speed the loom is usually run, changing the shuttle takes too much time, and the loom has to be slowed down to a standstill. This is accomplished automatically, the shuttle changed and the loom started again. The other method has been even more effective, and the necessary mechanism quite simple. At the proper moment the loom sets in operation a lever which pushes a fresh bobbin from a mag azine into the shuttle at the moment it lies stationary in the shuttle box, and the same movement releases a catch and the empty spin dle drops out. .
With the old-fashioned heddle only the sim plest and most regular webs could be woven, the number of heddles being limited to six. The demand for a greater variety in color, pat tern and texture led to the invention of the dobby, a lever operated by a projecting pin which engages in the pattern chain. The dobby is not operated alone but in a series, or °bat ranging in number from 10 up to 25. Each dobby works a harness connecting with a certain set of warp threads in forming the shed, and the more dobbies on the loom the greater variety possible in the fabric. For
highly ornate and figured patterns the most ef fective mechanism is the Jacquard attachment, patented by a weaver of yons, Joseph Marie Jacquard, in 1801. This machine lends itself readily to use with any loom. It may be de scribed as a means of controlling the shed. A revolving prism or is so perforated as to receive certain selected needles, which in turn govern a set of perpendicular hooks. These hooks lift or depress the threads of the warp, so that the weaving is no longer of neces sity simply °under or over?" How many threads are to be skipped is determined by a perforated card-board, the perforations occur ring where the thread of the warp is to lie above the weft; but if the warp-threads are not to be raised no holes are cut in the cards, the needles do not enter the cylinder and the hook attached to the needle does not lift (by means of its neck-cord or loop of twine), the thread of the warp. A connected series of these cards, each with different perforations, makes an almost infinite combination of pat terns possible, as each card makes a different shed. As each card represents a single pick, a series for an intricate pattern is very large, reaching sometimes 30,000 cards.
The hand loom is still used for the manu facture of rugs and fine carpets, but the power loom, driven by various powers, electricity being the latest and in some ways the most economical, is used for almost any purpose. The ribbon loom, for instance, weaves simul taneously a number of narrow pieces. Many attachments, invented in a long series, have continuously and wonderfully decreased the need of any supervision of the loom, making it more and more automatic: thus a shuttle protector automatically stops the machinery if the shuttle fails to fly all the way across the warp; the filling stop motion protects the machinery from running on uselessly when the filling breaks or runs out; and take-up, let-off and warp-stop motions are further automatic devices. A very ingenious machine known as the Chernack circular loom is used in weaving tubular fabrics such as constitute the basis of fire-hose. This loom resembles in appear ance a knitting machine. Its shuttle travels around the circuit of upright needles in a circu lar track being, propelled by a pinching move ment of the rising and falling needles, in a fashion similar to jumping a fresh apple seed with the pressure of thumb and finger. This loom is used also for weaving wire.
Consult Ainley, A., 'Woolen and Worsted Loomfixing> (Lawrence, Mass., 1900) ; The Draper Company, 'Labor-Saving Looms' (Hopedale, Mass., 1907); International Library of Technology (Vol. LXX X, Scranton, Pa., 1905); Murphy, W. S., 'Textile Industries' (Vol. IV, New York 1912); Posselt, E. A., 'Manufacture of Narrow Woven Fabrics' (Philadelphia 1916).