AND STRAIN ON THE ACTION OF PHYSICAL FORCES. 
83 
Experiment XXIV. 
Annealed German-silver (2). 
Load iu kilogs. 
Increase of resistance 
in divisions of the 
platinum-iridium wire. 
Ratio of consecutive increases 
of resistance. 
1st 2 
21 
2nd 2 
51 
2-43* 
3rd 2 
59 
115 
4th 2 
65 
1T0 
5th 2 
90 
1'38 1st critical point. 
6 th 2 
117 
1'30 
7th 2 
143 
1-22 
8th 2 
326 
2-28 
9tlx 2 
1083 
3'32 2nd critical point. 
10th 2 
1156 
1-07 
The weight of the scale-pan, pulley, &c., was 2'5 kilogs., or 1'25 kilogs. on each part 
of the wire, therefore the total load at the first critical point is equal to 11 '25 kilogs., 
and that at the second 19'25 kilogs. Now the section of the wire at the two points 
is '00883 and '00876 per square centimetre; hence the load at the first critical point is 
1274 and at the second 2197 kilogs. per square centimetre. 
In Table VIII. will be found the loads at the two critical points and their relation 
to “ Young’s modulus.” 
Table VIII. 
Name of metal. 
Value of 
e in grms. per 
square centim. 
Load at the first 
critical point in 
grms. per square 
centim. = a. 
Load at the second 
critical point in 
grms. per square 
centim. =-/?. 
Ratio e : a. 
Ratio e : /3. 
Iron (1) . 
Nickel (1). 
Platinum (1). 
German-silver (2). 
Copper (2). 
Copper (1). 
Copper (3) . 
Platinum-silver (1) . 
Silver (1). 
Aluminium (1). 
Mean for all the different 1 
metals.j 
1981 xlO 6 
2175 „ 
1490 „ 
1291 „ 
1218 „ 
1160 „ 
1143 „ 
1051 „ 
742 „ 
673 „ 
2-070 xlO 6 
2-200 „ 
1-400 „ 
P274 „ 
1151 „ 
1115 „ 
1-230 „ 
1-081 „ 
•819 „ 
•730 „ 
3-009 x 10 6 
3-100 „ 
1- 520 „ 
2- 197 „ 
1'702' „ 
1-870 „ 
1-741 „ 
1-250 „ 
1120 „ 
9-6 x 10 s 
9-9 „ 
10-6 ,, 
10-1 „ 
10-7 „ 
10-4 „ 
9-3 „ 
9-8 „ 
9-1 „ 
9-2 „ 
6‘6 XlO 2 
7-0 „ 
9-8 „ 
6-0 „ 
6'8 A, 
6-1 „ 
6-0 „ 
6-0 „ 
6'0 „ 
9-8 x 10 3 
6-7 xlO 3 
* In this, as in several other experiments, the first of the ratios of consecutive increases is greater than 
several of those which follow, but this is probably clue to the fact that the weight of the scale-pan had 
been acting on the wire for some hours previous to the period of actual testing. 
M 2 
