11 
19 08-9. J Vibrational Neutral Points in Magnetised Iron. 
(by a different experimental method) that for any given normal loop the 
neutral points are thrust from or towards the cyclic extremes according 
as the vibrational intensities are greater or less. Thus for a cyclic ampli- 
tude of H = T9, B = 3170 (fig. I.a), the neutral points for the following 
ascending values of the decreased cyclic field, viz. H = 1T, T34, 1*6, and 
1*72, occur with vibrations of decreasing intensity of approximately 
W X D 07 = 9, 5, 2, and 1 respectively. 
It is also further evident that the neutral points are not only thrust 
towards the cyclic extremes the weaker the vibrations, but that they may 
occur quite close to it, provided the vibrational intensity is sufficiently 
reduced. For instance, with a field value of H = T83 removed from the 
cyclic extreme by so small an amount as 0*07, although the curves fail to 
fall below the horizontal axis, it has every appearance of doing so had the 
intensity of the initial vibrational train been only a little less than 
W x D 07 — 0*38 (fig. I.a). In any case, a higher limiting value of the 
neutral points occurs well within II = 01 of the cyclic extremes, for this 
particular value of the amplitude, if the mechanical vibrations are weak 
enough (see also broken line curve, fig. II.). On the other hand, the neutral 
points are thrust from the cyclic extremes the greater the vibrational 
intensity, until a lower limiting value of the decreased cyclic field is 
reached, beyond which vibrations of all intensities produce only induction 
decrease (fig. I., H = 0*95, 0*52, also the middle diagram of fig. II.). 
The above results apply to a cyclic amplitude of H — 1*9, B = 3170. At 
lower and higher amplitudes, viz. 11 = 1*25, B = 1270, and H = 2*7, B = 
10,400, the various neutral points with different vibrational intensities 
occur at lower and higher values of field respectively, and each corre- 
sponding neutral point for any given vibrational intensity is thus thrust 
from the vertical axis the higher the amplitude (fig. II.). At these three 
increasing values of cyclic amplitudes, the range of field through which 
the neutral points may shift with intensity, viz. H = 0*43, 0*54, and 0*67 
respectively, is also increased as the amplitudes are increased (fig. II.), but 
this must again contract as saturation values are reached. 
To sum up, the conclusions may now be stated more definitely and fully 
than in the previous communication. The neutral points which occur when 
vibrations are superposed upon the decreasing cyclic field symmetrical 
about the origin are thrust towards the vertical axis the less the cyclic 
amplitude and the greater the vibrational intensity, towards the cyclic 
extreme the greater the cyclic amplitude and the less the vibrational in- 
tensity. There are thus lower and higher limiting values of the decreasing 
field through which the neutral points may shift, and both must vanish in 
