14 
Proceedings of the Royal Society of Edinburgh. [Sess. 
cyclic residual magnetisation are reached in the ordinary way by with- 
drawing the field at the cyclic amplitudes. But as these extreme and 
symmetrical positions are departed from, the curves for the same inter- 
mediate values of positive and negative cyclic residual magnetisation 
plotted against increasing values of W x D 0 ' 7 become wholly unsymmetrical. 
To so great an extent is this the case that the decrease of the cyclic 
residual magnetisation has, for the lowest value of vibrational intensity, viz. 
W x D 0 ' 7 — 2*2, wholly vanished when B= +8700 is reached, to be immedi- 
ately replaced by increase at only slightly lower values, viz. B = + 8020 
and +7500 (fig. III.). These curves further show that the direction of the 
induction change is not independent of the vibrational intensity. They 
first rise somewhat above, afterwards may fall largely below the horizontal 
axis. The neutral points which therefore occur are thrust from or towards 
the positive extreme of residual magnetisation according as the vibrational 
intensities are greater or less. Thus, for values of cyclic residual mag- 
netisation between the limits of B = zb 9100, the neutral points for the 
following ascending values of B— +7200, +7700, +8020, and +8700 
occur with vibrations of decreasing intensity, viz. W x D 0 ' 7 = 10'4, 6*9, 4*8, 
and 2*2 (fig. IV.). Thereafter, vibrations of all intensities between the 
above experimental limits increase the cyclic residual magnetisation to 
a greater extent the less its value. When the zero of residual magnetisa- 
tion is passed, the positive induction change, now decrease in reference to 
the negative magnetisation, continues at somewhat increased values until 
the negative extreme is reached. 
These results do not differ essentially from those obtained with cyclic 
field. The shift of the neutral points is subject to essentially the same 
laws, although the direction of the induction changes is opposite in 
the two cases. At a later stage (Section III.) it will be shown that even 
these apparently opposite effects disappear when the results for cyclic 
field and cyclic residual magnetisation are expressed, not in terms either 
of magnetisation or of field, but of field change. 
II. Electric Oscillations. 
Apparatus. 
Experiments were in the first place tried with the mild steel wire 
*092 cms. diameter, already used, and the results obtained for transverse 
oscillations will be given later. Owing to the effect of the oscillations being 
mainly confined to the surface of the wire, the galvanometer readings were, 
