The latter is more likely to retard than aid in the solution of the problem. A differential speed of the spindles has been proposed, but no data exist by which a correct judgment can be formed. If by simple means an approximation to an equal twist can be obtained a great step towards the solution of this extremely difficult problem will have been made. The whole question is environed with difficulty and requires constant attention to a number of little points, but the advance made during the past few years is so remarkable that a good deal of hope can be entertained as to eventual success. In the meantime weft is being spun successfully on small wooden pirns which possess the great advantage of allowing the whole of the yarn to be unwound from them, and thus save the waste often made by “stabbed” cops. A frame for this purpose, made by Messrs. Howard and Bullough, is shown in Fig. [202], and about 400 grains of No. 20’s yarn can be wound on each.
Fig. 198.HILL.
Fig. 199.HILL.
Figs. 200 and 201.
(383) With reference to the details of the machine it has latterly become the practice to drive both tin drums positively, so that there is no variation in the twist of the yarn on different sides of the machine. Such an arrangement—made by Messrs. Asa Lees and Co., Limited—is shown in Fig. [203], the course of the ropes being clearly indicated by the figures attached. The lift of the spindles varies from 5 to 6 inches, and their gauge from 21⁄2 to 23⁄4 inches. The diameter of the front roller is usually 1 inch.
