The shuttle with its bobbin, containing the yarn of the filling, is much the same as is used in the hand looms, except for form and size, which varies according to the requirements and size of the warp being used. At first only one shuttle was used, but in 1760 Robert Kay invented a mechanism by which several shuttles containing different grades or colors of yarn might be used. Each throw of the shuttle across the width of the goods is called a "pick."
In making a cloth with plain weave, that is, with every thread interlacing with every other, as in darning, only two harnesses are required, but the modern loom may have up to about twenty-four harnesses so that an infinite variety of weaves may be obtained. Various cams and levers move the harness frame and so raise or lower the threads required for the design.
The Jacquard loom is arranged on a different principle. In this loom, all kinds of fancy weaves may be obtained as in table linen, tapestries and carpets. Each warp thread is supplied with a separate hook and by means of perforated card the desired threads are raised or depressed at each throw of the shuttle. The cards are worked out by the designer. A set of a thousand or more cards may be required to produce the desired design. Jacquard looms are sometimes to be seen at fairs and expositions weaving handkerchiefs with some picture design.
[Illustration: JACQUARD HAND LOOM Weaving Ingrain Carpet at Hull House.]
The great variety of weaves found in the textiles of to-day are modifications of a few fundamental weaves invented in the earliest times.
[Illustration: DIAGRAM OF FANCY KNIT GOODS]
These do not include the many fancy weaves, too numerous to classify, and the open work weaves, made in the Leno loom, in which some of the threads are crossed. Knit goods are made by the interlooping of a single thread, by hand or on circular knitting machines and lace by an analogous process, using several systems of threads. Felt is made up of matted fibers of fur and wool and has no thread structure.
The plain weave is the most common, nearly all light weight goods being thus woven. In plain weaving, each thread of both warp and filling passes alternately over and under the threads at right angles. This makes a comparatively open cloth, requiring the smallest amount of yarn for the surface covered. This weave is used in nearly all cotton goods, as in muslins, sheetings, calicoes, ginghams, and thin woolen goods. Even in the plain weave variety is obtained by having some of the threads larger than others, either in warp or filling or both, thus producing stripes and checked effects.