352 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Copper Wire. 
Length = 97 ‘50 cms. 
Area of cross-section = *0006026 sq. cms. 
Stretching weight = 300 grams. 
No. 
Temp. 
Elongation for 
300 grams. 
No. of 
Observations. 
M. 
1 
23°*8 C. 
*03630 cm. 
8 
13*15x10 11 
2 
25 *3 
*03693 
8 
12*90 
3 
29 *7 
•03308 
10 
14-40 
4 
35 *5 
•02977 
10 
16-00 
5 
39 *1 
•02765 
9 
17-23 
6 
42 *6 
•02703 
8 
17-62 
7 
47 *4 
•02693 
7 
17-69 
8 
50 *1 
•02727 
12 
17*47 
9 
56 *8 
•02861 
8 
16-66 
10 
59 *0 
•02938 
8 
16T4 
11 
63 *7 
•03065 
8 
15-54 
12 
70 *5 
•03126 
6 
15-24 
13 
81 *3 
•03186 
8 
14-95 
14 
93 *2 
•03205 
8 
14-86 
15 
108 *0 
•03236 
10 
14-72 
16 
118 *5 
•03249 
10 
14-66 
17 
127 *0 
•03267 
11 
14-58 
18 
119 *9 
•03201 
9 
14-88 
19 
107 *0 
•03085 
8 
15-44 
20 
95 *5 
02999 
8 
15-88 
21 
82 *8 
•02919 
8 
1632 
22 
70 -0 
•02852 
5 
16-70 
23 
60 *0 
•02835 
7 
16-80 
24 
52 *9 
•02878 
8 
16-55 
25 
47 *3 
•02979 
6 
16-02 
26 
41 *2 
•03087 
8 
15-43 
27 
34 *5 
•03254 
8 
14-64 
28 
30 *0 
•03452 
8 
13-80 
29 
21 *2 
•03175 
8 
15-02 
Vertical Wire. 
30 
16 *3 
•03736 
6 
12-75 
temperature reached 30°. On allowing the wire to cool to the temperature 
of the room, there was a distinct increase in the modulus, so that a 
permanent change had been produced. 
Platinum Wire. 
The behaviour of platinum was different from that of the other three 
metals. With them the effect of a weak current was to produce a fall in 
the modulus, whereas in the case of platinum there was a rise with a 
current which produced a change of less than 3°. As the current was 
gradually strengthened, there was a steady increase in the modulus ; in 
