The operation of crossing is performed by doup healds. In these an additional loop or half heald carrying a stave at the bottom is slung through the eye of an ordinary heald (Fig. 57). For the purpose of description, the whole of this heald will be termed the doup. This heald is used for crossing purposes, while two or more ordinary healds are provided for the purpose of varying the working, if necessary. The draft for cloths, Figs. 53 and 55, is as shown by Fig. 56. The crossing thread is drawn through two healds and passes under the backing thread as shown. [Illustration: FIG. 56.] [Illustration: FIG. 57.] However, the heald No. 2 can be used to raise the crossing thread on the left-hand side of the backing thread, although it is drawn to the right of it at the front, as whenever the back heald is lifted, the loose stave of the doup is lifted also, and the crossing thread is thus free to be wrought by No. 2. The weaving of the plain is performed by either No. 2 and the doup, or by Nos. 1 and 2. In weaving the gauze portion, healds No. 1 and the doup are used only. Four jacks are required--one for the back heald, one for No. 1 heald, one for lifting the whole doup when weaving gauze, and a fourth for raising the half loop when necessary to release the crossing thread. To weave the design Fig. 55 with the given draft, at the bottom pick No. 2 heald and the loop will be raised, at the next pick above the whole doup requires lifting, at the third No. 2 and the loop, at the fourth the doup, at the fifth No. 2 and the loop, at the sixth the plain commences and the doup is raised, at the seventh No. 1 is raised, eighth the doup, ninth No. 1, tenth the doup, which completes the pattern, the eleventh being a repeat of the first. It is not necessary that the crossing should be round one thread only, but may be round three or four; to do this, of course, the crossing thread would have to be drawn under three or four backing ends in the healds. The crossing may also be in opposite directions, say-- [Illustration: () () )( )( () () )( )( FIG. 58.] as in Fig. 59, where the crossing thread passes over two backing ends. Every alternate end is, in this case, douped contrarily, the same healds being used--the difference being made in the draft. This style is called netting.