STRAIN ON THE PHYSICAL PROPERTIES OP MATTER. 
823 
Experiment X. 
The piano-steel wire used in Experiment VII. was, after the removal of the boxes, 
tested with suspended cylinders of different masses. The temperature ranged from 
10° C. to 15° C., and the vibration-period from 3 - 934 seconds to 4'60S seconds. 
Total mass 
Logarithmic 
of the vibrator in 
decrement due to 
grammes. 
internal friction. 
164 
•0003602 
838 
•0003763 
1512 
•0003547 
Experiment XI. 
The annealed copper wire of Experiment IX., after having been tested in the 
manner described in this experiment, was tried with much lighter loads. The 
temperature ranged from 17°'9 C. to 18° C., and the vibration-period from 6’301 
seconds to 7'36 3 seconds. 
Total mass of the 
vibrator in grammes. 
Logarithmic 
decrement due to 
internal friction. 
1570 
4635 
•0002756 
•0002653 
Experiments X. and XI. teach us that both for hard-drawn and annealed wires the 
internal friction is as independent of the load for light loads as we have seen it to be 
for heavy ones. We must, however, in such experiments as these be careful to begin 
with the heaviest load first, as loading tends more or less to produce a diminution of 
the internal friction, which is partly permanent and partly sub-permanent, provided no 
sensible permanent elongation results from the loading. Care should also be taken, 
in changing from the heavier load to the lighter one, to avoid shocks. If these pre¬ 
cautions be not taken, the logarithmic decrement will probably be found less for the 
heavier load than the lighter one. 
The Effect of Loading on the Torsional Elasticity. 
It is, I believe, generally assumed that the torsional elasticity of a wire is 
independent of the load, but apparently no experimental evidence has been brought 
forward in support of this assumption, at any rate as far as large stresses are 
