192 THE DEVELOPMENT OF KAW COTTOK 



by the author consists of a pendulum, a catch to hold it 

 at a definite altitude, and a smoked plate on which the 

 pendulum traces its swing with a delicate bristle stylus. 

 At the lowest point of the swing the apex of the pendulum 

 meets the end of a slot in a piece of tough paper and carries 

 it along with it. In so doing a bunch of fibres is broken, 

 these fibres having been mounted across a gap 10 milli- 

 metres wide in the after-portion of the paper, and left to 

 bear the shock of the impact by cutting the sides of the 

 gap as before, the portion of paper remaining behind the 

 gap being held firmly by a peg. The pendulum swings 

 up to a certain point when it has only the inertia of the 

 slotted piece of paper to overcome; when it also has to 

 fracture a fibre or bunch of fibres, it swings up to a less 

 extent ; the difference is measured from the smoked trace, 

 and gives by calculation the number of gramme-centi- 

 metres of energy expended in breaking the fibres, or (on 

 dividing by the number of fibres) the resistance to impact 

 of a single fibre. 



The method has great advantages, but requires very 

 careful sampling, if the full advantage of speed is to be 

 secured, and it also necessitates the counting of single 

 fibres. It will probably be possible to introduce a 

 machine which will obviate both these disadvantages, 

 and make such testing a practicable piece of routine. The 

 time occupied in making the tests with the ordinary 

 machine works out at ten minutes for each complete cycle 

 of operations on each bunch of ten to twenty fibres, five 

 of these being tested for each sample. The probable error 

 of determinations thus made is very low, since a bunch of 



