5 12 MR JAMES RUSSELL ON THE SUPERPOSITION OF MECHANICAL VIBRATIONS 



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 diagrams a and b illustrate the above deductions, and are self-explanatory. 

 The continuous lines represent the normal loops without vibrations; the dash and dotted 

 lines, the loops with permanently acting vibrations for the same values of field and 

 induction at cyclic extremes respectively. 



The experimental results show that the first deduction is fulfilled for the three 

 magnetic metals examined, in the annealed and in the quenched condition alike. At 

 every corresponding point of the loops the differential permeability is, so far as observed, 

 greater with than without permanently acting vibrations. The second deduction is 

 also supported by the results in so far as residual magnetisation, coercive force, and 



THEORETICAL DIAGRAMS 



ACQ NDIT10NS 



WITHOUT viB RuTiONi 5 



WITH VIBRATIONS. LIMITING VALUE THAT OF 



FiElD — — — — INDJCT ION 



FIELD AND INDUCTION — 



hysteresis loss are invariably increased for the same value of low field at cyclic 

 extremes, while coercive force and hysteresis loss are decreased, residual magnetisa- 

 tion only being increased in quenched nickel, for the same value of induction at cyclic 

 extremes. 



Further, the experimental results obtained do not exhaust all the possibilities of the 

 effects of vibrations on magnetisation. For the same value of induction amplitude 

 the descending and ascending arms of the loops, with and without vibrations, generally 

 cross in the first and third quadrants respectively, as represented in diagram a (dotted 

 curve), but in quenched nickel in the second and fourth quadrants respectively (see 

 fig. XVI. ), a position between the extreme positions represented by diagrams a and 6 

 (dotted curves). 



The question therefore arises whether a condition of some magnetic metal or alloy 

 could not be found, so that the arms of the loops would cross in the third and first 

 quadrants respectively, as represented in diagram b (dotted curves). In this case not 



