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PROCEEDINGS OF THE AMERICAN ACADEMY. 



The only method applicable was the following. In taking any one 

 of the magnetization-reversal curves by 1-step reversals, for instance 

 curve 7 (Figure 8), the observer introduced at one or two places, as at 

 the fourth and fourteenth reversals, a reversal consisting of a larger 

 number of steps. If the curve be plotted from 1-step reversals only 

 and, after it has been drawn, the other reversals marked in their 



proper places, some con- 

 clusion as to the effect of 

 the latter can be estab- 

 lished. The case in which 

 the iron has attained a 

 constant cyclic change has 

 been discussed ; it is evi- 

 dent that for that condi- 

 tion this method will 

 decide at once whether or 

 not the number of steps 

 has any effect. If the iron 

 is still in the stage of 

 variation, the early part 

 of the curve, one cannot 

 be so sure. However, if 

 there is no abrupt change 

 in the direction in going 

 from the 1-step reversal 

 just before the 3-step to 

 that just following, and 

 if the 3-step lies to within 

 the expected error on the 

 curve, it seems highly 

 probable that the number 

 of steps is immaterial. If 

 the general shape of the 

 curve in that region is about like that in the corresponding regions of 

 the curves preceding and following, where the region consists wholly of 

 1-step reversals, the probability is correspondingly increased. Of course, 

 no such similarity as this exists for the first three curves of a set with 

 moderate flux density. 



The method of attack that has been outlined was carried out for 

 approximately the following values of B per square centimeter, 3000, 

 6000, 7400, 10,100, 13,500, and 19,300, in the order named, and the 

 data obtained have been plotted, in six sets, giving the curves shown. 



Figure 8. Set II: B 6000: seventh mag- 

 netization; O indicates 1-step reversals; X 3- 

 Btep reversals. 



