Mechanical Vibrations upon Magnetization. 471 



Cyclic Diagrams. — In figs, v., VI., VII., X., XI., and XII. the 

 continuous lines represent the normal loops without vil rations, 

 the dotted curves the loops with permanently acting vibrations 

 (B conditions). Figs. v. and VI. (annealed steel) show four 

 sets of hysteresis loops with and without vibrations, cor- 

 responding to four field values at cyclic extremes — viz., 

 H = 0*16, 1*46, 2'6 and ll'O. The induction amplitudes 

 (without vibrations) cover the wide range between B = 56 

 and B = 15,750. Jn figs. VI., VII., XI., and xn. comparison 

 may be made between the smaller and larger normal loops 

 and the dotted loops with permanently-acting vibrations in 

 each figure for the same value of field and induction at cyclic 

 extremes. Fig. VI. is for annealed steel, fig. vil. for annealed 

 nickel, figs. XI. and XII. are both for quenched nickel, the 

 former for low, the hitter for high cyclic amplitudes. In 

 fig. X. for quenched iron the comparison is for the same low 

 value of induction o ly. 



On the other hand, the dash-line curves of figs. xi. and xn. 

 show for quenched nickel the effect of superposing vibrations 

 under the A conditions at all stages of the smaller of the 

 normal loops in each case. Compare with curve 3 of fig. I. 

 for annealed iron under the same conditions. 



Results. 



The summary of the results given below is based on all 

 the experimental work. In this abstract it has been impos- 

 sible to reproduce all the diagrams. 



A and B Conditions. — In all cases vibrations increase 

 induction. In high fields B v /B approximates to unity. In 

 nickel the induction reached is greater (if the field be not 

 unduly increased) when vibrations are superposed (A con- 

 ditions) than one half the induction change on reversals 

 when vibrations are permanently acting (B conditions). 

 The reverse is the case for iron and steel. 



B Conditions. 



Permeability. — In all cases B v /B is approximately a 

 maximum when dB Y /dII is a maximum. In annealed nickel 

 the maximum value of B v /B = 10, in annealed iron and 

 quenched nickel about 3, in annealed steel 4, and in quenched 

 iron and steel a decided minimum. In quenched nickel 

 the B v /B curve shows two well-marked maxima ; the second 

 when dBy/dH is a maximum, the first at a lower value of 

 field. Two corresponding maxima are merely indicated in 

 quenched steeL In no other case are they observable. On 



