82 
MR. H. TOMLINSON ON THE INFLUENCE OF STRESS 
Experiment XXIII. 
Annealed iron wire. 
Load in kilogs. 
Permanent increase 
of resistance represented by 
divisions of platinum- 
silver wire. 
1st 
5 
2nd 
8 
3rd 
17 
4th 
21 
5tli 
29 
6th 
33 
7th 
42 
First critical point 8th 
120 
8| 
118 
9th 
40 
94 
25 
10 th 
30 
104 
35 
11th 
0 
111 
15 
12th 
83 
124 
177 
13th 
223 
13| 
389 
Second critical point 14th 
2356 
144 
2028 
15th 
1421 
15| 
2052 
16 th 
36 
16| 
24 
17th 
304 
Third critical point 174 
1603 
18 th 
Broke 
It will be seen from the above experiment that there is a critical point at the 
8th kilog., another at the 14th kilog., and a third at the 17th kilog. 
The two critical points were determined in all cases by finding the two points 
where the ratio of the increases of resistance produced by consecutive equal loads is 
greatest; the next experiment furnishes an example of the method adopted. 
