Worsted makes the best weaving doups for strong work, but for lighter work cotton is mostly used, being finer and cheaper. Sometimes polished linen yarn is used and makes a very smooth doup, but does not give the wear.
Small metallic rings are sometimes used on the loops of the doups, and the warp drawn through these rings; this suits for yarn with much fibre on it, as it keeps the fibre from getting twisted into the doups, but the rings cut the doups faster than ordinary yarn working in them would.
Instead of a slip heald in front, doups with a lingo on each have been used, with the mails for the standards as shown at No. 2, Fig. 138, so that the doups cannot fall out of them, and the yarn when drawn up by the back harness in shedding raises the doups and lingoes up with it. The weight of the lingoes must be such as will suit the strength of the warp to be used--not too heavy for it to lift nor too light, so that in the cross shed the doups would be drawn through the mails. These doups being separate, are easily built in the harness and very easily repaired by the weaver when they break, but they break too frequently. It is, of course, only for a strong warp that this method of working is suitable, and even for it, although it works very well, the principle is not good.
The gauze harness which will probably be most frequently met with, at least in the cotton trade, is shown in Fig. 138. It is an older harness than that described, having been patented in Macclesfield in 1876 in a somewhat different form. The difference between this and the preceding chiefly consists in the method adopted for slackening the yarn, and the jacquard may also be specially built to suit for this. In setting this loom the harness and mails are tied up and levelled as before, but when working the back rail is kept down, as it usually is for gauze work, say about 1/2 in. lower than the eyes of the mails. Each whip thread has its own slackener, the slackening apparatus consisting of a harness wrought either by the same jacquard that works the figure, or by an extra one, when much pattern is required.
The connections of the needles with the hooks are shown at A, the two bottom needles being connected with the two front and two back hooks, the former for working the gauze and the latter for working the slackeners. This harness is intended for a 1-round 3-gauze, and is mounted on a 10-row machine with an 8-row cylinder on it. It is not necessary that the back harness for slackening should be raised so high as the figuring harness is, and for this reason, as well as that it makes the harness more direct and avoids friction, it is tied to two sets of levers as shown at G and G^1; they are made of brass and are fastened on two rods, one about 4 in. above the other, so as not to come into contact with each other when rising or falling. The points of the levers are fastened to the two back rows of hooks as shown, and the harness is tied to wire hooks on these levers; F is the neck of the harness, D the cumber board, and N the lingoes, which are much heavier than those used for the figuring harness, from 6 to 10 per pound being the weights frequently used, according to the class or weight of the work.