The weft is in cop form, and fits on a peg inside the shuttle, the loose end from the cop nose being drawn through the shuttle eye by a strong inhalation of air by the weaver. To prevent excessive waste the manufacturer should obtain yarn well copped, the cops hard, free from nicked places caused by the minder having his ends down; clear apertures at the bottom of the cop, which should also be free from backlashing--that is, ends hanging slackly below and over-lapping those previously wound on. Weft cops, or pin cops, should be five inches in length, and as thick as the shuttle will admit of. Weft yarn is selected according to its evenness, good cover or nap, and cleanliness. BEATING UP. The shot or pick of weft often being put through the shed, is at a distance of five inches from the woven cloth, and requires pushing up into close contact with it. The motion of the slay performs this operation. As explained on page 60, the slay is a beam of wood carrying a reed, and having a reciprocating motion to and from the fell of the cloth, imparted to it by the cranks on the shaft (Figs. 22 and 43.) The beam is supported on two vertical rods, called slay swords, attached near the bottom of the loom to a vibrating or “rocking” shaft. The slay is away from the cloth or front centre a sufficient time to give opportunity for the propulsion of the shuttle through the shed. Were the crank-shaft at the same level as the slay-sword pin, the dwell at each end of the stroke would be exactly equal--a dwell of some duration, however slight, it is obvious, there must be. However, the centre of the crank-shaft is at a lower level than that of the connection of the crank-arm with the slay-sword ears, and thus the slay dwells longer at the healds than at the cloth. As the slay makes some 200 strokes per minute, the variations of speed at the back and front centres are scarcely observable, but by means of exact measurements a certain amount of dwell may be traced at the back centre.