348 
Proceedings of the Royal Society of Edinburgh. [Sess. 
the rate of increase when the modulus was rising in value. This 
diminution continued up to the highest temperature to which the 
experiment was carried, but the rate was not uniform, for at about 105° 
the rate of decrease fell. Moreover, the modulus did not fall to so low a 
value as it had when the current was first started. This part of the curve 
is denoted by the circles. 
Iron Wire. 
Length = 97*9 cms. 
Area of cross-section = *0005474 sq. cms. 
Stretching weight = 500 grams. 
No. 
Temp. 
Elongation for 
500 grams. 
No. of 
Observations. 
M. 
1 
20°*4 C. 
*04741 cm. 
8 
18*51 x 10 11 
2 
23 *9 
*05073 
8 
17*30 
3 
27 *5 
*04880 
8 
17*98 
4 
34 *2 
*04658 
8 
18-84 
5 
40 *8 
*04482 
10 
19-58 
6 
47 *1 
•04387 
8 
20-04 
7 
50 *6 
•04347 
8 
20T9 
8 
57 *0 
•04357 
6 
2014 
9 
64 *9 
•04421 
7 
19-85 
10 
73 *9 
•04526 
8 
19-39 
11 
82 *8 
•04633 
8 
18-94 
12 
90 *7 
•04764 
8 
18-42 
13 
100 *2 
•04833 
8 
18-16 
14 
108 *0 
•04880 
10 
17-98 
15 
116 *1 
•04916 
6 
17-85 
16 
104 *3 
•04935 
8 
17*78 
17 
90 *5 
•04880 
8 
17-98 
18 
75 *0 
•04736 
8 
18*53 
19 
67 *2 
•04623 
9 
18-98 
20 
61 *8 
•04588 
8 
19-13 
21 
60 *6 
*04626 
5 
18-97 
22 
55 *6 
•04663 
7 
18-82 
23 
49 *5 
•04771 
8 
18-38 
24 
38 *7 
•04958 
8 
17-70 
25 
25 *3 
•05174 
8 
16-96 
26 
21 *3 
•04686 
8 
18-73 
Vertical Wire. 
27 
16 *1 
•04852 
8 1 
18-09 
The current was then gradually diminished in strength, and readings 
taken at various temperatures. It was found that the value was not so 
high as when the current was increasing, and about 104° it reached a 
minimum. From this point on to 62° the rate of increase was nearly the 
same as the rate of decrease with the increasing current. The reading at 
60°*6 is probably incorrect, as it does not lie on any smooth curve that 
