392 



MR. C. O NEILL ON AN APPARATUS 



drawn off: the results came out as follows^ the tempera- 

 ture of the water being 56° F. : — 



Larger cylinder: 1000 grains of water drawn off, at 5 

 different levels, equal 1080 grs. weight; or 0'926 gr. water, 

 equal i grain weight. 



Medium cylinder: 1000 grs. water drawn off, at 7 different 

 levels, equal a mean of 47*4 grs. ; or 2i'0() gr. water drawn 

 off equal i grain weight. 



Smaller cylinder: 10,000 grains water drawn off equal 

 21 grs.; or 476*1 grs. water equal i gr. weight. 



These practical data are as near the calculation as I ex- 

 pected them to come, and I have used them in my ex- 

 periments. 



In the case of the fibre or thread stretching before break- 

 ing, a correction will have to be made for the extent of 

 stretch which lowers the floating cylinder in the water ; 

 to make this correction it will be necessary to determine 

 experimentally for each cylinder how much water must be 

 drawn off to lower it a given distance when it is free to 

 move. This is very easily done, by means of an index and 

 a graduated scale. The medium cylinder, for example, is 

 lowered ci inch by drawing off. 250 grains of water : it is 

 evident if a fibre of cotton had stretched a tenth of an inch 

 before breaking, the whole water drawn oft' would be 250 

 grains more than if it had remained rigid ; this quantity 

 must therefore be deducted from the quantity drawn off, 

 in calculating the breaking-weight. The temperature of 

 the water will also infiuence the results slightly ; but I 

 have always used water between 50° and 60° Fahr., and the 

 correction is too slight to be required for the purposes to 

 which I have yet applied the apparatus. 



As an example of the method of using the apparatus, I 

 give the results of an experiment upon Sea Island cotton, 

 made with the medium glass cylinder. A single fibre was 

 taken by a forceps, and, by means of a cameFs-hair pencil, 



