G4 
MR, H. TOMLINSON ON THE INFLUENCE OF STRESS 
Influence of Permanent Extension on the Temporary Alteration of 
Resistance caused by Longitudinal Stress. 
It has been asserted in Part I. that the elasticity of a wire is diminished by 
permanent extension not exceeding a certain limit. In order to furnish still further 
evidence in favour of this assertion some experiments were made on the influence of 
permanent extension on the temporary alteration of resistance produced by longitudinal 
stress. 
Experiment XIII. 
A piece of copper (3) was subjected to loads which were gradually increased, and 
after the removal of each load the temporary alteration of resistance was determined 
from the mean values got by testing with from one to five measures of water. 
Number of 
measures used 
for the 
permanent 
extension. 
N umber 
proportionate 
to alteration of 
resistance of wire. 
Difference 
between consecutive 
alterations of 
resistances. 
Number proportionate 
to temporary alteration 
of resistance caused 
by stress of 1 grni. per 
square centim. 
Difference 
between consecutive 
alterations of 
resistance. 
5 
860 
644 
6 
862 
2 
648 
4 
7 
865 
3 
652 
4 
8 
878 
13 
658 
6 
9 * 
912 
34 
681 
23 
10 
952 
40 
692 
11 
11 
985 
33 
693 
1 
Experiment XIV. 
A similar piece of wire was loaded with from 12 to 14 measures of water, and after 
the removal of each load tested in a similar manner to the above. 
Number of 
measures used 
for the 
permanent 
extension. 
Number 
proportionate 
to alteration of 
resistance of wire.* 
Difference 
between consecutive 
alterations of 
resistances. 
Number proportionate 
to temporary alteration 
of resistance caused 
by stress of 1 grm. per 
square centim. 
Difference 
between consecutive 
alterations of 
resistance. 
12 
1288 
421 
13 
1418 
130 
416 
-5 
14 
1574 
156 
409 
-7 
* Neither these numbers nor those in column 4 are on the same scale as the corresponding numbers in 
the last experiment. 
