RESEARCHES IN MAGNETISM. 
639 
Temperature, deg. C. 
Magnetometer. 
Hours of observation. 
8-6* 
692 
b. m. 
1 15 p.m. 
34-6* 
656 
2 0 
48T 
636 
3 0 
48-4* 
635 
3 15 
677 
607 
3 40 
73-3 
598 
4 10 
74'8 
596 
4 18 
75-8 
594 
4 27 
76T* 
593 
4 50 
910 
566 
5 25 
95-2 
559 
5 45 
96-6 
556 
6 0 
98-2 
554 
6 15 
98-8* 
552 
6 33 
1131 
523 
7 4 
119-8 
511 
7 20 
122-7 
505 
7 43 
123-8 
502 
8 0 
123-8* 
502 
8 12 
151-2 
441 
8 42 
155-3 
430 
8 56 
157-1 
425 
9 5 
158-3 
422 
9 20 
158-4* 
422 
9 30 
Now began to cool. 
131-2 
487 
10 20 
129-8 
491 
10 40 
129-1 
495 
11 0 
1291* 
495 
11 10 
108-8 
538 
12 0 
105-5 
542 
12 21 a.m. 
104-3* 
545 
12 45 
104-7 
546 
1 0 
103-4 
546-5 
1 13 
79-6 
589 
2 15 
78-4 
591-5 
2 28 
77-4 
593 
2 35 
76-4 
593-5 
2 45 
76-0* 
594 
2 52 
28-2- 
667 
4 10 
23-4* 
675 
4 25 
17-8 
684 
4 45 
16-8* 
685 
4 54 
10-8 
691 
5 35 
10-3* 
691-5 
6 0 
The points at which the temperature of the bar was most nearly uniform (marked 
with an asterisk in the table) have been selected from the above readings and plotted 
in Plate 68, fig. 60, where the lower line shows the process of heating and the upper 
line the process of cooling. There is no appearance whatever of hysteresis, in spite 
of the very considerable amount of magnetic change which the bar underwent. 
§ 122. In dealing with a subject such as the magnetisation of iron, to which so 
much attention has been given, it is difficult to master or to acknowledge adequately 
the labours of former observers. The comprehensive summary of G. W iedemann, 
4 N 2 
