The tappet is fixed on the upper frame-work of the loom and short treadles arranged above it. To these the healds are attached and lifted by the plates, being drawn down afterwards by springs and the healds. In a recently-improved form the treadles raise the jacks to which the healds are attached, giving a straight lift. These tappets are seldom used for more than 8 healds and 12 picks to the round. Above this extent in tappet work, a Woodcroft sectional tappet is used, arranged at the loom side. In these tappets the projections (called risers and fallers) are removable, the tappet being adaptable to different patterns up to 14 staves and 20 picks. In the Yorkshire loom, Fig. 23, the tappets are placed at the loom side, and are connected with the top of the healds by rods. Tappets possess the advantage over other shedding motions of larger capacity, such as the dobby: (_a_) in lower first cost; (_b_) steadier and stronger lift without risk of hooks slipping; (_c_) in having a split shed--_i.e._, a shed which has one portion pulled down while the other is drawn up, saving time. Dobbies and jacquards generally have a sunk shed, and if by those machines a shed 2 inches deep is required, the lifting knives have to be raised the whole distance, from the bottom to the top. [Illustration: FIG. 44.] [Illustration: FIG. 45.] CLOTHS WOVEN BY TAPPETS. Among the cloths woven on tappets there are twills, cloths in which a figure is woven diagonally across the cloth by raising the healds consecutively. They are in large variety, being woven on three shafts upwards and not confined to the lifting of a single heald at each pick; as in some cloths two or three out of a larger number may be raised, but the same number is up at every pick, although moving one end or more at each pick. A serge is a modification of a simple twill woven in this manner. Fig. 44 represents a 4-shaft twill rising one in four, while Fig. 45 shows a 4-end twill rising two in four, called a denim, swansdown, or cashmere twill. The satin weave is a broken twill--that is, instead of lifting consecutively at each pick, an end, or in some cases two ends, are passed over, as shown in Fig. 39 (sateen). The ends are lifted in this order: 1, 3, 5, 2, 4. A 5-stave, showing a weft satin, is the standard for _sateen_. The satin or broken twill applies to any number of twill staves--_e.g._, a 12-stave satin, passing 4 ends over, lifts 1, 6, 11, 4, 9, 2, 7, 12, 5, 10, 3, 8. A perfect satin never shows contiguous ends lifting together, as such would give a “spotty” appearance. As almost all the weft shows at one side of the cloth, the parallelism of the threads gives to this weave its well-known lustre, but unless fine yarns and reed with heavy pick are used a very frail structure is the resultant.