MR, H. TOMLINSON ON THE INFLUENCE OF STRESS 
5‘2 
Table I. 
Name of metal. 
Condition. 
Specific resistance 
at 12° C., i.e., 
resistance in ohms 
of 1 cubic centim., 
between opposing 
faces 
= R. 
Increase of 
resistance per unit 
produced by stress 
of 1 grm. per square 
centim. 
— X. 
Increase of 
resistance per 
unit which 
would be caused 
by stress suffic¬ 
ing to double the 
length of the 
wire 
=y■ 
Increase per 
unit of specific 
resistance which 
would be caused 
by stress suffic¬ 
ing to double the 
length of the 
wire 
= 2. 
Iron (1) . 
Annealed . 
1074 x 10 -8 
2111 x 10-12 
4T80 
2-618 
Ii’on (2)*. 
Hard drawn . 
1217 xlO" 8 
2100 x 10-12 
4-289 
2-639 
Iron (3) . 
Hard drawn . 
1201 xIQ' 8 
2197 x 10-12 
8-699 
2-057 
Piano steel (1) . 
Hard drawn . 
1653 x lO- 8 
1910x10-13 
3-619 
2-081 
Piano steel (2) . 
Hard drawn . 
1882 xlO' 8 
1831x10-12 
3-602 
2-084 
Platinum (1) . 
Hard drawn . 
2233 x 10-12 
3-341 
2-239 
Platinum (11 . 
Annealed . 
1434 xlO- 8 
2285 x 10-12 
3-404 
2-252 
German-silver (1). 
Annealed . 
2830 xlO" 8 
1501 x 10-12 
1-937 
0-107 
German-silver (2). 
Annealed . 
1545 x 10-12 
2-099 
0’345 
German-silver (1). 
Hard drawn . 
2713 xlO" 8 
1892x10-13 
2-138 
0-138 
Copper(1) . . . . 
Annealed . 
240'8 x lO -8 
2210 x 10-12 
2-564 
0-934 
Copper (1) .... 
Hard drawn . 
244-0x10-8 
1988 x 10-12 
2-880 
Copper (3) .... 
Annealed . 
201-4x10-8 
2324 x 10-12 
2-656 
1-070 
Copper (2) . . . . 
Annealed . 
187-3 x lO" 8 
2396 x 10-12 
2-918 
1-012 
Platinum-silver (1) . 
Annealed . 
3236 x lO" 8 
2346 x 10-12 
2-464 
0-624 
Platinum-silver (1) . 
Hard drawn . 
8127 xlO- 8 
2437 x 10-12 
2-530 
Brass (1) .... 
Hard drawn . 
834 xlO" 8 
2302 x 10-12 
2-275 
o-ioi 
Brass (2) .... 
Hard drawn . 
656-7xl0- 8 
2229 x 10-12 
2-203 
0-231 
Zinc (1) . 
Hard drawn . 
4406 x 10-12 
3-379 
2113 
Silver (1) . . . . 
Annealed . 
161-9x10-8 
4272 x 10-12 
3-851 
1-531 
Silver (1) .... 
Hard drawn . 
173-7x10-8 
4561 x 10-12 
3-487 
1-703 
Aluminium (1). 
Hard drawn . 
316-7x10-8 
1883 x 10-12 
1-260 
-0-420 
Aluminium (1). 
Annealed . 
311-3x10-8 
1896 x 10-12 
1-276 
-0-262 
Tin (1) . 
Drawn . 
1166 xlO' 8 
10546 x 10-12 
2-920 
1-630 
Lead (1) . 
Drawn . 
2142 xlO" 8 
17310x10-12 
’ 
2-885 . 
1-613 
Remarks on Table I. 
It will be seen from the above table that the specific resistance of iron is more 
increased by a given amount of elongation than that of any of the other metals, and 
that the specific resistance of aluminium is actually decreased by stress in the line of 
flow of the current; this latter fact being signified by a minus sign placed opposite 
aluminium in the sixth column. 
It is also remarkable that the value of z for the alloys, platinum-silver, German- 
silver and brass should be considerably less than that of their components; and this 
circumstance, taken in connexion with the comparatively large increase of resistance of 
iron, would suggest that there is some relation between increase of electrical resistance 
caused by rise of temperature and that due to mechanical stress. 
* Iron (2), iron (3), steel (1), steel (2), and brass (2) were tested some years ago by a method similar to 
the one here described. 
