90 
MR, H. TOMLINSON ON THE INFLUENCE OF STRESS 
and as it was expected that experiments on the permanent increase of resistance would 
throw some light on this influence of time, several trials were made with a view 7 of 
ascertaining whether a wire will, wdien under the action of considerable stress, show 7 
greater and greater increase of length until it breaks, or whether the time-curve of its 
increase of length will be asymptotic. 
Experiment XXVI. 
A piece of copper (3) having been loaded for some time with six measures of w 7 ater 
was still further loaded with one measure, this being allowed to enter very slowly into 
the pail attached to the wire ; the current from a Daniell’s element was kept flowing 
through the “ bridge ” circuit, and the alteration of resistance observed by noting the 
position of the light on the scale. 
Time in minutes 
after the completion 
of the loading. 
Increase of resistance* 
for each minute 
in terms of the deflection 
of the light in scaled 
divisions. 
Difference of increase 
for consecutive 
minutes. 
1 
45 
2 
31 
14 
3 
25 
6 
4 
24 
1 
5 
18 
6 
6 
16 
2 
7 
16 
0 
8 
15 
1 
9 
17 
_2 
10 
10 
7 
11 
13 
-3 
12 
14 
-1 
13 
13 
1 
14 
7 
6 
15 
5 
2 
16 
8 
-3 
17 
10 
_2 
18 
8 
2 
19 
5 
3 
20 
7 
— 2 
From the last experiment we learn that, though the wire had been' so carefully 
loaded and the room free from vibrations of any sort, the increase of resistance did 
not, shortly after loading, take place smoothly, but the difference of increase of 
resistance for consecutive minutes became alternately greater and less. 
In the next experiment the increase of resistance is measured by the number of 
divisions of the platino-iridium wire through which it was necessary to move the 
sliding-piece in order to restore the balance, and the times recorded are those taken 
to produce the increase of resistance. 
* Each scale-division here represents an alteration of resistance equal to about ten-millionths of the 
•whole. 
