OBSERVATIONS UPON COTTON. 411 



upon a glass plate, and, one end carried by a moistened 

 camers-hair pencil between the gummed flaps, it is settled 

 in its place, the pencil communicating sufficient moisture, 

 and the flaps are then carefully pressed together with the 

 finger ; the loose end is secured in a similar manner to 

 another triangle. This holds them perfectly tight ; and, 

 when dry, the triangles can be suspended upon the hooks, 

 or secured in any other way in the testing-apparatus. 



It was soon found that cotton hairs differed very much 

 among themselves in tensile strength, and that a cotton hair 

 was not of equal strength throughout; the resistance was 

 at a minimum when the hair was held by its extremities, 

 and the point of maximum resistance was found to vary in 

 different qualities of cotton, but always to lie nearer the 

 seed-end of the cotton-fibre than to its tapering extremity, 

 generally at about two-thirds or three- fifths of the length 

 of the hair from its weaker end. In order to illustrate 

 this physical proof of the varying strength of a single hair 

 in different parts, I give the results of experiments in which 

 one hair has been broken several times in succession, being 

 freshly connected after every break, so long as it was 

 possible to get hold of the remainder of the hair. In one 

 case of Sea Island cotton (SA-d-) I got five breaks from one 

 hair, as follows, the lengths given being those between the 

 points of suspension : — 



ist break 1*7 inch, broke with i8'i grs. at 0*5 in. from one end. 

 and „ ro „ 70-9 „ o'l „ 



3rd „ 0-8 „ 97'i „ o-i „ 



4th ,, o*5 „ 126*2 ,, 0"2 ,, 



5tli V 0-2 „ 133-3 



In Edisto Sea Island cotton I succeeded in two instances 

 in getting respectively seven and eight breaks from the 

 hairs ; in every case, except in the first break, the fibres 

 broke quite close to one of the fastenings. The particulars 

 are as follows : — 



