1908-9.] Vibrational Neutral Points in Magnetised Iron. 37 
irreversible effects of loading and unloading, but to the irreversible effects of 
all other disturbances, whether produced by electric, mechanical,* or thermal 
means (temperature change). Wherever these are associated with a complex 
magnetic aeolotropy such as .may be impressed upon the magnetic material 
by cyclic field change, there the shift of the (vibrational) neutral points, and 
the consequent dependence of the direction of the irreversible induction 
change upon the intensity of the disturbance, independent of the values 
of the magnetisation or the field, either or both of which may be zero, will 
be in evidence. 
As on former occasions, I desire to thank the Royal Society of London 
for placing at my disposal Government grants for furthering these 
researches. 
* In a later communication than that already referred to (p. 2), Professor Maurain states 
that “la courbe normale depend un peu clu l’amplitude des cycles de torsion.” See “Sur 
Faction de la torsion sur l’aimantation,” Journal de Physique , May 1907. In other words, 
the vibrational neutral points shift with the intensity of the torsional disturbance. 
( Issued separately November 16, 1908.) 
