107 (#161) ############################################ WOOLLEN YARN SPINNING 1 spindle-draft”-is the most important from the actual spinning point of view. From the mechanical point of view the sixth was the most difficult to attain, and was the last for which a satisfactory mechanism was invented.* It is impossible to emphasize too strongly the effect of spindle-draft and the extent to which it differentiates woollen yarn from worsted yarn which is twisted after roller drafting has been applied. In the first case the twisting and the drafting conjointly and simultaneously decide the position of the fibres in the thread : in the latter case the drafting rollers decide the relative positions of the fibres and the twisting simply binds the fibres together in a more or less parallel-spiral form. Two questions with reference to woollen mule spinning lead directly on to a thorough apprehension of what is actually taking place- (a) why is it usual to employ such a thick-ended, untapered spindle ? (b) why do the two ends of a ruptured sliver so readily join together (piecen ”) during the spinning period ? The effect of the thick-ended spindle can be felt during the "spindle-draft " on the hand-wheel and can be seen on watching the mule itself. As the yarn slips over the spindle tip it “slackens,” and as it again winds up to the spindle-top on the continued revolution of the spindle it " tightens.” Thus the drafting opera- “ tion in woollen mule spinning is not a steady draw but a draw in which there is a "give and take periodicity," in time, corresponding with the revolutions of the spindle. * The hand-mule, which automatically did everything except wind-up the spun yarn on to the cop or bobbin in satisfactory form, was extensively in use in Yorkshire up to twenty-five years ago. 107
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