UPON MAGNETISATION, AND CONVERSELY, IN IRON, STEEL, AND NICKEL. 497 



tensities of mechanical vibrations. The normal cycles are the same in both cases. The 

 other curves show the effect of increasing the intensity of vibrations in the ascending 

 order indicated by the numerals 1, 2, and 3. The induction reached at cyclic 

 extremes is greater, the greater the intensity of vibrations, irrespective of the order of 

 -uperposition. 



It may be noted, however, that one-half the average induction change with 

 vibrations permanently acting (fig. II.) is in all three cases a little greater than the 

 induction reached when vibrations are superposed at the limit of the normal cyclic 

 obtained without vibrations (fig. I.). 



As the cyclic extremes are departed from, a glance at the curves shows that the 



2000 



1000 



B. CONDITIONS A. CONDITIONS 



CURVES 1,2.3. WITH VIBRAT/ONS OF INCREASING INTENSITY 



order of superposition under the A and B conditions produces apparently very different 

 results. 



A Conditions. — The induction change due to superposed vibrations is greater with 

 increasing field, and is always in the same direction as the field change ; but if the field 

 be decreasing the induction change due to vibrations is first against, afterwards with, 

 the field change. Increase of the intensity of vibrations thrusts the neutral point 

 towards the vertical axis, producing at the same time a progressive collapse of the two 

 arms of the loops. 



B Conditions. — For any given intermediate va]ue of cyclic field, the rate at which 

 induction is changing is progressively increased with vibrations of increasing intensity. 

 But the rate of magnetic change always remains greater with increasing than with 

 decreasing field. Hence the areas of the loops (energy loss per cycle) progressively 

 increase with vibrations increasing in intensity. 



