18 
MR. H. TOMLINSON ON THE INFLUENCE OF STRESS 
Mode of experimenting. 
The wire to be examined passed through a small hole, H, fig. 5, made in a stout 
table, and was clamped at its upper extremity into a brass block, B, the latter resting 
on the table and being sufficiently secured by a heavy weight, W, placed on the top of 
it. Near the lower extremity, which was looped to receive a scale-pan, was clamped 
a second small block, A, to one end of which was attached a light mirror of the kind 
Fig. 5. 
employed with reflecting galvanometers ; this mirror, used in connexion with a scale 
and lamp, enabled the observer to detect very small differences of torsion ; the distance 
of the scale from the mirror was 1200 scale-divisions, and the length of each wire at 
the commencement of each experiment was 95 centims. 
In the following table will be found the results of the experiments made with the 
different metals, these latter being for the most part pieces of the same wires as had 
been used in the determinations of “Young’s modulus,” but in each case carefully 
re-annealed. 
