978 



COTTON-SPINNING 



the finer will be the yarn. For spinning coarse numbers or low counts, for example, 

 six card-ends are usually transmitted through the first drawing head, and converted 

 into one riband. Six such ribands again form one in the second draught ; six of 

 these again go together into the third sliver ; and this sliver passes five-fold through 

 the last draught. By this combination 1,080 of the original card-ends are united in 

 the finished drawn sliver = 6x6x6x5. The fineness of the sliver is, however, in 

 consequence of these doublings, not increased but rather diminished. For, by the 

 drawing, the card-end has been made 625 times longer, and so much smaller ; by the 

 doubling alone it would have become 1,080 times thicker; therefore the original thick- 

 ness is to the present as 1, to the fraction iWu ; that is, supposing 1,072 feet of the 

 riband delivered by the card to weigh one pound, 625 feet, the sliver of the last 

 drawing, will also weigh a pound. 



The rearmost or last drawing roller has a circumference of nearly 4 inches, and 

 makes about 150 revolutions per minute ; hence each of these drawing heads may 

 turn off 35,000 feet of sliver in 12 hours. 



Fig. 562 is a complete view of a drawing frame as manufactured by Hetherington 

 and Sons, having the usual modern contrivances for increasing the quality and the 

 amount of work done, viz., a stop motion behind the frame to stop the frame when a 

 sliver breaks ; a roller plate to prevent roller laps. The coiler motion, by means of 

 which the sliver is placed in the can in circles overlapping each other on the principle 

 described in fig. 563, the can roving frame ; 4 rows of draught rollers instead of 3 ; 

 and lastly, an apparatus for lifting all the roller weights from off the rollers at any 

 time when the frame may be stopped. 



A further improvement is now added to drawing frames, viz., a front stopping motion. 

 The object of the back stopping motion is to prevent inequalities arising in the sliver 

 from the occasional breakage of one of the slivers which are being combined together. 

 The front one has a different purpose. It is obvious that whenever the rollers which 

 carry forward the sliver from the front drawing rollers to the can fail to take up 

 the cotton as fast as it is delivered, there arises an accumulation, which, from the great 

 speed at which the sliver passes through the machine, rapidly increases. All this accu- 

 mulation was formerly so far wasted that it was -necessarily sent back into the mixing 

 room to be worked over again. By the use of a front stopping motion the drawing 

 frame is now stopped instantly, and all accumulation of this kind prevented. 



Hitherto the riband or sliver has received no twist, but the fibres have lain in a 

 linear, parallel manner, holding together in a loose mass. But in the further pre- 

 paratory processes, some reduction of the thickness of the riband is necessary, so that 

 it may gradually approach the thickness finally required in the yarn. The natural cohe- 

 sion of the fibres when placed side by side will not now be sufficient to carry the sliver 

 forward. At the next stage, therefore, a slight convolution or twist is given to it 

 simply for this purpose. This operation takes place in the Slubbing Frame. The 

 twisting should go no further than to fulfil the purpose of giving cohesion, otherwise 



it would place an obstacle in the way of 

 the future attenuation into level thread. 

 The combination of drawing and twisting 

 is what mainly characterises the spinning 

 processes, and with this fifth operation 

 therefore, commences the formation of 

 yarn. As, however, a sudden extension 

 to the wished-for fineness is not practic- 

 able, the draught is thrice repeated. 



Fig. 563 is a section of the can, or lan- 

 tern slubbing frame, the ingenious in- 

 vention of Arkwright, which, until within 

 the last 50 years, was the principal ma- 

 chine for communicating the incipient tor- 

 sion to the spongy cord furnished by the 

 drawing frame. It differs from that frame 

 in nothing but the twisting mechanism ; 

 and consists of two pairs of drawing 

 rollers, a and b, between which the sliver 

 is extendud in the usual way ; at e there 

 are brushes for cleaning the rollers ; and 

 d is the weight which presses the upper 

 set upon the lower. The wiping covers 

 (not shown here) rest upon a b. The surface speed of the posterior or second pair 

 of rollers in 3, 4, or 5 times greater than that of the front or receiving pair, ac- 



