ON THE MEASUREMENT OF MAGNETIC HYSTERESIS. 
93 
Ring H. Fine steel vdre.* 
AY = •560HbBo-1120. 
Ring IV. 
AY = - 
Thin sheet iron.! 
314HbBo-225. 
H,. 
Bq. 
y.. 
AY (obs.). 
AY (cal.). 
Ho- 
Bo. 
11. 
AA^ (obs.). 
AY (cal). 
3T0 
590 
190 
125 
-538 
1-400 
420 
300 
59 
-69 
3-93 
925 
236 
307 
-90 
1-687 
677 
402 
134 
51 
4-08 
1180 
290 
540 
213 
1-884 
927 
491 
225 
174 
4-76 
1820 
382 
1130 
1102 
2 - 32 
1800 
776 
660 
635 
6T2 
3960 
647 
4310 
4370 
3-24 
4160 
1285 
2220 
2125 
7-48 
6170 
819 
8300 
8330 
4-01 
5710 
1424 
3440 
3367 
8'91 
8090 
907 
12820 
12390 
4-93 
7250 
1470 
4980 
4825 
■ 10-98 
10190 
927 
18100 
17780 
6-45 
9030 
1400 
6940 
6975 
13-66 
12070 
983 
23460 
23880 
8-89 
10880 
1225 
9750 
9965 
21-89 
15040 
688 
34330 
38280 
12-99 
12640 
975 
12670 
14075 
32-42 
16720 
516 
41320 
52080 
17-20 
13760 
800 
14830 
17695 1 
43-91 
17680 
403 
45770 
64500 
23-61 
14720 
622 
16670 
22225 1 
Effect of an Electric Current U]oon E[ysteresis:\. 
§ 70. If ail electric current be sent along an iron wire it jDrodnces a circular 
mao;iietic force which tends to link tos;ether the mao netic molecules in circular chains. 
We may expect that this linking of the molecules will make them less susceptible to 
the influence of a longitudinal magnetic force H, and that in consequence, for a given 
range dz Hq both the range of the longitudinal component, B, of the magnetic 
induction and also the energy dissipated by hysteresis in each cycle would be 
diminished. The effect deserves a systematic investigation, but this up to the 
present we have not been able to carry out. We must content ourselves with 
recording some qualitative experiments which show that the expected effect of an 
electric current actually occurs. 
The experiments were made in March, 1896, by one of us with the heljD of Mr. 
John Talbot. An iron wire aljout 1 niillim. in diameter was used, and an alternating 
current was employed in the piimary circuit, giving rise to a steady deflexion of the 
dynamometer coil proportional to the energy dissipated by hysteresis in each cycle. 
In an experiment made on March 9, a steady current varying from 0 to IT23 am 2 :»eres 
was sent through the wire, with the result that the hysteresis was diminished. No 
observations were made to determine Hg, Bg, or W in absolute measure, and thus we 
can only represent W by means of the deflexion of the dynamometer. The table 
shows the result of the experiment, the third column recording the percentage 
diminution in the hysteresis occasioned by the passage of the current. It will be 
seen that the strongest current diminishes the hysteresis by nearly one-quarter, 
* Loc. cit., p. 995. t Loc. cii., p. 1002. 
I The experiments of Gerosa and Finzi are described by Professor Ewixu, ‘ Magnetic Induction in 
Iron, &c.,’ .3rd Edition, p. 330. 
