146 THE DEVELOPMENT OF RAW COTTON 



consequently some curious effects upon the grader. If 

 the pure- strain lint has not been cultivated particularly 

 well, it will show such " uglinesses " as would, in com- 

 mercial variety samples, be necessarily associated with 

 such irregularities of length and strength as a pure strain 

 cannot show ; the result is that the spinning-mill will give 

 far better results than the grader would imagine possible. 



Possible Ignorance of this fact led to some serious 

 Mistakes in consequences within the author's experi- 



Grading. encej an d it would be well that those who 

 may be concerned with the production of pure-strain 

 cottons in the future should be aware of the risk. 



Yarn Strength. This is the only strength that really 

 matters. Cotton is grown to be spun. If it spins well it 

 is good cotton; if ill, bad. 



We now meet with a new set of questions, many of 

 which are still unanswerable in any exact expression; 

 and although they have been dealt with more fully than 

 other parts of our subject by previous authors, it may 

 be well to present the case afresh. The main considera- 



Unimpor- ^ on * s t ^ s: ^at the strength of yarn has 

 tanceof Hair very little to do with the hair strength as 



Strength, determined by breaking strain, only about 

 a quarter of the available tensile strength being realized. 

 The strength of yarn is thus almost entirely dependent 

 on the hold which the individual hairs take upon one 

 another. Yarn does not break primarily through rupture 

 of hairs, but through slip of hair on hair. Strength of 

 yarn, within limits, follows the amount of twist which is 

 put into it, even the variation in strength of yarn after 



