474 Mr. J. Russell on the Superposition of 



neutral points, the statement is nevertheless quite applicable 

 to the A conditions whatever the intensity of the vibrations. 

 It is, however, not applicable to the B conditions when the 

 intensity of the vibrations is such that their effects have 

 not reached a limiting value, and results cannot be concisely 

 stated in terms of magnetic hysteresis : to do so requires as 

 complete a knowledge in each case of the BH loop as is 

 required without vibrations. Moreover, loops obtained when 

 vibrations are permanently acting are stable at any point to 

 subsequent " offs" and " ons " of the same vibrations. 



Molecular Theory. — §182 of ' Magnetic Induction in Iron' 

 may be consulted. The general nature of the argument is 

 shown by the following quotation : " Any kind of disturbance 

 that will give the molecular magnets intervals of freedom, or 

 of diminished constraint, will tend to do away with hysteresis." 

 This statement also appears completely applicable if the dis- 

 turbances be superposed under the A conditions. Under the 

 B conditions I prefer a deduction relative, not to hysteresis, 

 but to the rate of magnetic change with field change, subject 

 to any condition which molecular theory may demand. If 

 the differential permeability in low fields be greater with 

 than without vibrations, in high fields the reverse necessarily 

 follows. 



My deductions therefore are : (1) That if the cyclic 

 amplitude be not unduly increased the differential permea- 

 bility will be greater with than without permanently acting 

 vibrations ; (2) that the increase of differential permeability 

 with vibrations may be associated either with increase or 

 decrease of residual magnetization, coercive force, or hysteresis 

 loss, but that there is greater probability that those properties 

 which depend upon hysteresis will be increased with vibra- 

 tions for the same value of field than for the same value of 

 induction, and conversely, that there is greater probability 

 that they will be decreased with vibrations for the same value 

 of induction than for the same value of field. The experi- 

 mental results support these deductions, which in the paper 

 are illustrated by diagrams. 



Electric Oscillations. 



The effects of electric oscillations in coils surrounding the 

 iron previously dealt with * are precisely the effects of vibra- 

 tions upon magnetization. The experimental methods being 



* 'Notes on the Effect of Electric Oscillations (Co-directional and 

 Transverse) on the Miignetic Properties of Iron." Proc.R.S.E. vol. xxvi. 

 p. 33, 1905. Also 'Science Abstracts/ vol. ix. section A, Abst. 1119. 



