214 (#286) ############################################ WOOLLEN AND WORSTED SPINNING larities introduced there will not only make control of the delivery difficult, but will result in defective slivers and ultimately in an irregular thread. A review of present-day practice with reference to delivery into spinning machines almost completely demonstrates the principles involved. Thus the follow- ing varieties are to be noted :- (a) The woollen mule—surface delivery without any tension ; (b) The French drawing frame-pull from lightly held (upright) balls on staves ; (c) The cone drawing-box-pull from more heavily held (horizontal) or lightly held (upright) bobbins; (d) The open drawing-box-pull from heavily held (horizontal) bobbins. In the case of (a) there must be no strain on the sliver at all. In the case of (6) the arrangement shown results in a draw into the back rollers with practically no straining of the sliver. In the case of (c) as little twist as possible is often inserted during the delivery of the slivers so that as a rule the twist is calculated to ensure a feed without straining of the sliver, and for this pur- pose the upright position of the bobbin is better than the horizontal position of the bobbin, although the horizontal position is more frequently adopted. In the case of (d) the twist is inserted to ensure fibre-control during drafting, and is usually such that the horizontal position of the bobbin may be adopted without fear of any straining of the slivers. Investigations into the strain on a given sliver under the different forms of sliver delivery here referred to, might well be taken in hand. Whatever form may be decided upon in taking 214
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