In the process of weaving it is necessary to hold the warp somewhat tightly, each portion at the same tension, and to obtain this condition the cloth is pulled forward by the taking-up roller as it is woven; but the warp is held back by the friction of weighted chains or ropes on the collars of the beam. The warp passes upwards from the beam, over the back rest, and thence to the back of the healds; between the back rest and healds are the lease rods--a large one with a smaller rod nearer the healds. By means of these rods the warp is separated into equal portions, two ends passing alternately over or under the thick rod; those passing over the thick one also run under the thin rod. The rule commonly observed for four healds is to have the ends passing the first and the third heald over the thin rod, and those drawn through the second and fourth over the thick rod, and consequently under the thin one. The first heald is the one nearest the front of the loom; the draft is 1, 3, 2, 4, and applies to plain cloth, although the first and second healds are worked as one, and the third and fourth together. Respecting the two ends which pass together at the lease rods, the one through the front heald is to the left of the one through the third heald; whilst with the other couples, the end through the more forward heald is to the left of the other. The weaver, bearing these rules in mind, can thus find the place of any broken end. The healds are suspended on each side of the heald roller A by means of straps and cords, which are shown. The portion of the heald roller supporting the back healds is larger than for the front ones; this is to make the former when lifted make the shed at the same angle as the front healds. Below are seen the crank shaft B, and the tappet shaft C, driven from it at exactly half the speed. The latter shaft bears the picking plates H and shedding tappets K. The slay, supported by the slay-sword[2] D on the rocking shaft is shown also. It carries the reed at E, held in position by the slay-cap F. The back rest at G, over which the warp passes, and the weight levers and driving pulleys are also noticeable parts. The cloth is woven pick by pick, and the whole action of the loom may be comprised in repetitions of the operations contingent on putting in one pick. Supposing the warp to be in position and the whole machine in weaving order, the first movement is to open the warp into two parts, and is called shedding; the second is to pass the shuttle through the opening thus made, called picking; and thirdly, to beat up the weft close to the pick last put in--technically, to the fell of the cloth. In addition to these, auxiliary movements are taking place for winding on the woven cloth, keeping it distended, and checking the motion of the loom in case of accident. [2] In addition to the references given in the text, each article is shown on Plate V. SUNDRY FITTINGS FOR LOOM.--FIG. 21.