1908-9.] Vibrational Neutral Points in Magnetised Iron. 25 
opposed or assisted respectively the magnetisation change. But no such 
assumption can be made. The oscillation constants of the primary and 
secondary of the air transformer vary with the number of 1 mm. sparks in 
series, with oscillation solenoids No. 1 and No. 2, and with the permeability 
of the iron wires. Hence there may be an alternate rising and falling 
resultant of the damped oscillations in the secondary citcuit. The amplitude 
of the first secondary oscillation may therefore be less than a succeeding 
amplitude of opposite phase. 
When, however, the number of 1 mm. sparks in series are sufficiently 
increased, the large amount of damping thus introduced into the primary 
circuit may become the dominating factor, independent to a large extent of any 
other. A comparison of tig. Vl.ab (oscillation solenoid No. 1) and fig. VII. 
(oscillation solenoid No. 2) supports this assumption. For strong oscillations, 
the curves with uncrossed oscillation connections relative to the decreasing 
positive field are in both cases invariably higher than those obtained with 
crossed connections. It is therefore highly probable that the amplitude of 
the first oscillation is greater than that of those which follow, and that its 
phase opposes the magnetisation change. On the other hand, the relative 
position of these curves is reversed for weak oscillations when solenoid No. 
2 is used (fig. VI.). This result is at least not unintelligible in view of a 
rising and falling resultant of the damped secondary oscillations under the 
varied resonance conditions under which the experiments were made. 
In any case, it is obvious that the induction change in the iron wires 
is sensibly affected in a very definite way by the conditions under which 
the damped secondary oscillations are produced. 
Notwithstanding these differences, the conclusions arrived at relative to 
the shift of the neutral points when the cyclic field is decreasing, and the 
consequent dependence, within the limits of the range of shift of the 
direction of the induction change upon intensity (see p. 11), are fully 
applicable to electric oscillations, whether co-directional or transverse. This 
is sufficiently evident from a cursory comparison of the diagrams in each case, 
without again entering into details. Figs. Vl.a b and fig. VII. (co-directional 
oscillations) and fig. IX. (transverse oscillations), showing the induction 
changes due to superposed oscillations of increasing intensity for various values 
of decreasing cyclic field plotted against the number of 1 mm. sparks in series 
as abscissa3, are entirely similar in their main features to figs. I. and I.a 
showing the induction changes due to superposed mechanical vibrations of 
increasing intensity for various values of the decreasing cyclic field plotted 
against W x D 0 ' 7 as abscissae. So also are fig. VIII. (co-directional oscillations), 
fig. X. (transverse oscillations), and fig. II. (mechanical vibrations) entirely 
