ON THE MEASUREMENT OF MAGNETIC HYSTERESIS. 
75 
Load, 
Ho = 
4-524. 
Ho = 
11 -0. 
Ho = 
16-24. 
kilogrammes. 
Bo. 
W. 
Bo. 
W. 
Bo. 
W. 
0 
1233 
494 
5750 
6520 
8660 
11710 
2 
1663 
726 
7150 
8320 
9940 
13700 
4 
2250 
1183 
8700 
10030 
11150 
15050 
6 
3030 
1776 
10030 
11970 
12050 
16300 
8 
3880 
2402 
11150 
13120 
12650 
16830 
10 
4915 
3140 
11730 
13680 
12980 
16600 
12 
5475 
3540 
11970 
13500 
13010 
16300 
14 
5920 
3770 
12000 
12920 
12820 
15550 
16 
5870 
3820 
11690 
12300 
12760 
15080 
18 
5750 
3610 
11400 
11590 
12580 
14500 
20 
5490 
3400 
11070 
11150 
12300 
13780 
22 
5160 
3060 
10740 
10630 
12010 
13430 
24 
4840 
2800 
10410 
10220 
11720 
12980 
Id order to save space on the diagram, the zero for the four upper curves differs 
from that for the two lower ones. The numbers on the diagram will prevent any 
confusion. 
In each case, as the tension increases, both and W rise to maximum values, the 
tension corresponding to the maximum values diminishing as Hq increases. Next to 
the similarity between the curves for and W for a given value of Hq the most 
striking feature is the great increase in both Bq and W occasioned by tension when 
Ho is small. Thus for Hq = 4‘524 a pull of 14 kilogrammes raises Bq from 1233 to 
5920, and W from 494 to 3770. The magnetic force was not carried to values high 
enough to obtain the Villari reversal of the effect of tension. 
Effect of Torsion within the Elastic Limit. 
§ 53. In July and August, 1899, we made a long series of experiments on the 
effect of torsion upon the magnetic qualities of iron and steel. The arrangements for 
applying torsion were very simple. A Avooden wheel 24'7 centims. in diameter was 
mounted on a brass tube as an axle, and this tube revolved in a bearing. The wire 
under test passed through the solenoid and through this tube, and was clamped at 
one end to the wooden wheel, while the other end was held in a vice. The vice and 
the hearing of the wheel Avere mounted on a stiff wooden beam so that the Avire was 
parallel to the beam, Avhich was placed at right angles to the magnetic meridian. 
The magnetising solenoid Avas so fixed that the wire passed along its axis. 
To apply a torsional couple to the wire, a weiglit was hung from the edge of the 
wheel by a flexible string wrapped round the wheel. When we wished to give the 
wire a definite twist, the wheel was clamped in the desired position. 
L 2 
