Drawing-frames should never be placed in damp rooms, nor should the atmosphere of the room ever be allowed to become damp, as it tends to make the rollers " lick " the fibre, making a large percentage of waste. The opposite extreme of dryness should also be avoided, as it prevents the laying of the fibres parallel to each other, because they manifest a tendency to curl, which subverts the end in view.
Slubbing.—As previously defined, slubbing is to further attenuate the sliver, and draw the fibres into more perfect parallel order. Instead, however, of 6-8 slivers being put np, only two are usually condensed into one. The machinery, in its first working parts, is similar to that of the drawing-frame ; but, instead of the sliver—after this process called " slubbing"—being coiled in a can, it is wound upon a bobbin, or barrel, by means of the spindle and flyer ; the slubbing-frame belonging to the series of bobbin aud fly frames. It is generally constructed with about eighty spindles as a maximum number. These are of a size to fit them for the reception of bobbins 10-12 in. in height. The traverse is correspondingly large. In this frame, the cotton is first twisted, the attenuation of the sliver having proceeded so far, that, without this, its coherence would not be sufficient to pull the bobbin round when being drawn off in the subsequent process. As the stra.nd of fibres has to be further attenuated, and much twist would prevent this, no more is put in than is necessary for the above-mentioned purpose. A better opportunity for describing the flyer, and the differential winding motion, will occur subsequently, so it Reed not be introduced at this point.
Intermediate, or Second Slubbing.—This is, in all essential respects, a repetition of the slubbing process, the machine containing, however, rather more spindles than the slubbing-frame, and its bobbins being smaller-8-9 in. In spinning Nos. below 20's, it is not usually employed. The accompanying diagrams illustrate the method of applying the electric) stop motion to this important machine. In its operation, there are two occasions when the frame requires to be promptly stopped.
Two " slubbings " are put up to formoone thread, one of these may break, or the bobbin may become exhausted, and it is necessary that these occurrences should be detected immediately, otherwise the attenuation of the single thread, which would continue passing through, would cause a great amount of waste ; or, if permitted to pass into the spinning-frame, it would seriously depreciate the quality of the yarn produced. Numerous attempts have been made to obviate the mischief by mechanical
appliances, but without any satisfactory result, until the most perfect success was achieved by this invention.
As shown in Figs. 541 and 542, the bar on which the springs A are fixed is placed in con nection witla the positive pole of the battery or magneto-electric machine. The fluted roller B is in connection with the negative pole. The strands of cotton separate the spring_and the roller ; but when, through the breakage or exhaustion of one strand, they come into contact, the electric circuit is completed, and the magnet is charged, so as to attract downwards one end of the double lever F, the opposite end of which, rising into contact with a ratchet wheel, acts upon a clutch, and stops the machine through the medium of the usual appliances. The action of the working parts can be most clearly seen in Figs. 542 and 543, the latter being an enlarged view of the parts.
Roving.—This is a continuation of the above, the object being the same, and the means by which it is accomplished, identical. The sizes of the spindles and bobbins are further diminished, whilst the number of the former is increased, ranging from 140 to 200 ; the lift of the bobbin is 5-7 in. Sometimes a second, or fine, roving frame is used, where fine numbers are spun. It is often called a " jack " frame, and carries the fineness of the roving to 30-40 hanks.
For purposes of illustration and description, the roving-frame may be taken as representative of the dubbing and intermediate frames. In principle they are the same, and differ only in details. All belong to the class of bobbin-and-fly frames. The roving-frame (Figs. 544, 545), unlike the slubbing-frame, which draws its supply of the raw material from the sliver cans, is provided with a creel similar to, but necessarily smaller in detail than, that of the intermediate frame.