THE SPINNING PROPERTIES OF COTTON 85 



matter of words alone. In point of fact, some of the pure-strain 

 samples were condemned by graders as being weak, and yet 

 made most excellent yarn. 



Admitting then the possibility that the strongest yarn may 

 be spun from the weakest hairs, provided only that these hairs 

 have developed sufficient secondary thickening to form their 

 normal convolutions, it remains to see how this bears upon the 

 undoubted superiority of pure-strain lint. 



The explanation seems to lie in the frequency distribution 

 of single-hair breaking-strain. The pure strain of fine cotton 

 mentioned above had such a low breaking-strain under even 

 the optimum conditions of cultivation, that admixed rogue plants 

 and natural hybrids (formed when a portion of the strain was 

 exposed to crossing) could be detected by the greater strength 

 of their lint-hairs. It follows that any sample of fine cotton 

 derived from other than a perfectly pure strain must contain a 

 certain proportion of strong hairs. Now there is nothing in the 

 existing machinery which would tend to eliminate these strong 

 hairs, they being quite normal in all other respects ; they are 

 indeed less likely to be removed, and the percentage of them in 

 the sample probably increases as the successive preparatory 

 stages of spinning are survived. 



The presence of such strong, thick-walled hairs at any given 

 point in the yarn will weaken the yarn at that point, much as 

 the inclusion of an inch or so of horse-hair would weaken it, 

 simply because of the consequent reduction in hair-surface. 

 Such hairs being absent from pure-strain lint, so far as gametic 

 causes are concerned, the yarn produced from it largely escapes 

 this defect. The absence of such hairs is not easily perceptible 

 to the grader, who therefore inevitably under-estimates the 

 value of pure-strain lint. The whole matter opens up a number 

 of interesting problems in technology, in the physics of colloids, 

 and in agriculture, but it will suffice to consider the immediate 

 application. 



The invention of the comber has already been mentioned. 

 The function of this machine is to remove all short hairs. With 

 our present recognition of the similar undesirability of strong 

 hairs, it may well be asked whether it is not possible to devise 

 a machine which will eliminate them also. The advantages to 

 be obtained from the use of pure-strain lint seem to be very 

 appreciable, but an intelligent control and somewhat elaborate 



