(354) In the description of the governing motion, given in paragraph 339, it was shown that the rotation of the screw in the quadrant arm is made during the inward run of the carriage. There are some objections made to this procedure on the ground of the extra tension put on the yarn in the early part of winding, which is of some moment when fine or tender yarns are being spun. In Fig. 180 a side view is given of a motion made by Messrs. Dobson and Barlow, which is designed to obviate the necessity for altering the screw during the inward run, and provide means by which it can be made during the outward run. In lieu of the ordinary grooved pulley on the quadrant axis, a toothed wheel =U= is used, with which a toothed rack =R= can engage under circumstances presently to be described. The rack =R= is carried by a sliding frame =S=, which is fixed upon a longitudinal rod =T=, extending backwards in the headstock, and carried by brackets fastened to the floor. The rack is fitted at one end with an inclined foot, and at the other with a spring, which prevents too deep an engagement of the rack and wheel. The rack passes—during its outward stroke—over a frame fastened to the headstock, in which is a screw =X= on which is threaded the sliding stop =W=. The pitch of the screw thread is varied to correspond with the thread in the quadrant arm =Q=, and the screw is rotated by a ratchet wheel, with which a pawl, oscillated by a finger, engages. At the point =I= a loose tongue is hinged, which at the end of the stroke of the frame engages with the nut =W=. On the winding faller a sector =Y= is fixed, in which a stud, formed with two portions of different diameters, is bolted. On the counter faller a sector =Z= is fastened, carrying a screwed staple, to which is secured one end of a chain, indicated by dotted lines. The chain passes round the bowl =R= at the upper end of the pendant lever =O=, guided in brackets at the front of the carriage. The loose end of the chain is formed into a loop, which can be slipped on to either of the surfaces of the bowl in the sector =Y=. A hinged finger =L= is carried by a bracket on the rod =T=, and has a little range of movement in a circular direction.