(320) Referring again to Fig. 161, the ends of the copping rails have pins fixed in them, on which are anti-friction bowls, which run upon the edges of the copping plates. The latter are duplicated, so as to sustain the rail at each side, and thus maintain its vertical position. At one side of one of the plates =Y= is an ear =S^{ 1}=, which is threaded to correspond with a square threaded screw =S= passing through a fixed bracket fastened to the floor. In this way the screw =S= is free to revolve, but cannot make any longitudinal movement. On the end of the screw =S= a ratchet wheel is fixed with which a pawl =S^{ 2}= engages, which is oscillated so as to move the wheel one tooth at convenient times. The speed of the revolution of the screw varies according to the counts being spun, the elevation of the point of locking being more quickly effected when coarse yarns are being made than when the finer varieties are produced. Whatever may be the velocity at which this elevation is accelerated, the profile of the copping plates is such that the inner end of the copping rail =P= is lowered at a more rapid rate during the formation of the cop bottom than at a subsequent stage. The reason of this will be easily comprehended, if the description of the mode of building the latter be borne in mind. It was then shown that the traverse of the winding faller rapidly increased in extent until the full length of the cop bottom was built. It, therefore, follows that the descent of the locking lever must be largely increased at this period at a quick rate, in order to produce the result indicated. When the outer end of the copping rail begins to descend at a rate which more nearly corresponds to that of the inner end, it gradually approaches to the horizontal, and the vertical motion of the slide, locking lever, and faller is proportionately limited.
(321) The regulation of the winding faller as just described was the one which was usual until recent years. It has been found necessary, however, to obtain a more accurate regulation, so as to ensure that the faller wire shall be in its correct position when locking occurs, especially during the period between the beginning of a cop and the attainment of its full diameter. It is now customary to attach to the front end of the copping rail a loose plate =Q=, which is hinged at one end to the rail, and which carries at its outer extremity a pin and bowl resting upon a third inclined plate =Z=. By varying the profile of the plate =Z=, the regulation of the faller during the early part of its traverse can be accurately made and the proper position of the wire ensured. As a glance at the illustration will show, the upper edge of the copping rail is not straight, but is shaped so as to give a variable speed to the slide =L= in its vertical movement. The proper shaping of the copping rail gave rise to some difficulty, and it will be seen that the loose copping rail =Q= is shaped so as to produce the proper effect, while being much more easily adjusted.