TESTS OF THE STRENGTH OF SILK FIBRES. 63 
instrument is so constructed that the strain to which the fibre is sub- 
jected to break it, aud the stretch it sustains previous to rupture, are 
simultaneously taken and recorded, and we have, therefore, to present 
in this connection two sets of results. 
In making these tests the following method was employed: In the 
first place the cocoons were cut open and their layers separated, or they 
were submitted to the action of hot water and the fibres wound off upon 
pieces of card-board, each process furnishing the “dry” and ‘ wet” 
specimens respectively described in a preceding paragraph. From the 
loose fibre thus obtained sections of suitable length were taken at ran- 
dom for the individual tests, the ‘ wet” specimens having been previ- 
ously thoroughly dried. The two clamps holding the fibres in the in- 
strument during the tests were carefully set at a distance of 20 milli- 
meters apart, so that this distance represents the length of the fibre 
submitted to the strain. Experiments with woolen fibres showed this. 
distance to give the most uniform and satisfactory results, and is, there- 
fore, accepted as a standard for all our work. Although no special ex- 
periments were made with this regard on the silk examined, there is 
little doubt that it would be found equally satisfactory. 
In this part of the examination as in the measurements of fineness, 
we have adopted 350 as the best number of fibres to be tested to secure a 
satisfactory average, and as before, each separate result obtained was 
entered upon the record to be employed in any comparisons that it may 
appear to be desirable to name. For their more ready comparison the 
results obtained with the “dry” and ‘ wet” specimens, respectively, are 
placed side by side. The following table contains the results we have 
obtained: 
