WOOL. 



205 



the roving of fibres together. In a cotton roving or a cotton yarn 

 the more closely the fibres can cohere together and interlock spirally, 

 the better and more compact is the yarn when spun. This cohesive 

 tendency of the fibres of cotton to lie longitudinally is assisted by the 

 twist put into the strand of rove or yarn. The strength is therefore 

 increased and the length diminished according to the amount of twist 

 that is pub into the rove or yam. Every interspace that might arise 

 between individual fibres of cotton is taken up by the twist, which 

 causes the yarn to become level, round, and elastic. 



A Contrast. The fibres of a woollen roving being differently con- 

 structed, they are not necessarily parallel; to make them so would 



Fig. 131. Merino wool after willowing and oiling. 



deprive them of the lively undulations or spiral curls which most wool 

 fibres assume when on the sheep's back. A woollen rove is remarkable 

 for the crossing and interlocking of its fibres, and the numerous inter- 

 spaces that occur between the interlocked fibres. It will be seen in the 

 illustration that the fibres do not lie longitudinally together, but are 

 distantly crossed, leaving an interspace, and are held together by the 

 interlocking of the imbricated scales of the woollen fibres. The inter- 

 spaces allow the air to enter, and thus assist the fibres in bending grace- 

 fully outwards and becoming wavy after the natural growth of the fibres 

 during life. When the woollen fibres are spun into yarn the intercross- 

 ing and interspacing is not materially altered. The lucid surfaces of the 



