When cotton is intended to be woven into a fabric, such as calico, &c. the first operation consists in laying the requisite number of threads together to form the width of the cloth; this is called _warping_. Supposing there to be 1,000 threads in the width of a piece of cloth, then the yarn, wound on the bobbins as it leaves the hands of the spinner, must be so unwound and laid out as to form 1,000 lengths, constituting, when laid parallel, the warp of the intended cloth. The ancient method was to draw out the warp from the bobbins at full length on an open field (and this is still practised in India and China), but the _warping-frame_ is now employed, in which the threads are arranged, by means of a frame turning on an upright centre. When the warp is arranged round this machine, the warper takes it off and winds it on a stick into a ball, preparatory to the process of beaming or winding it on the beam of the loom. The threads in this latter process are wound as evenly as possible on the beam; a separator, ravel, or comb being used to lay them parallel, and to spread them out to about the intended width of the cloth. Arrangements are then made for _drawing_ or attaching the warp-threads individually to certain mechanism of the loom. In this process all the threads are attached to stays fixed to two frames, called _treadles_, in such a manner that all the alternate threads (1st, 3d, 5th,) can be drawn up or down by one heddle, and all the rest (2d, 4th, 6th, &c.) by the other. There are three movements attending every thread of weft which the weaver throws across the warp. In the first place he presses down one of the two _treadles_, by which one of the two heddles is depressed, thereby forming a kind of opening called the _shed_. Into this shed, at the second movement, he throws the shuttle, containing the weft-thread, with sufficient force to drive it across the whole web. Then at the third movement he grasps the _batten_, which is a kind of frame, carrying at its lower edge a comb-like piece, having as many teeth as there are threads in the warp, and with this he drives up the thread of weft close to those previously thrown. One thread of weft is thus completed, and the weaver proceeds to throw another in a similar way, but in a reverse order, that is, by depressing the left treadle instead of the right, and by throwing the shuttle from left to right, instead of from right to left. In the commonest mode of weaving the shuttle is thrown by both hands alternately; but, about a century ago, John Kay invented the _fly-shuttle_, in which a string and handle are so placed that the weaver can work the shuttle both ways with one hand. [Illustration: Weaving by hand.]