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PROCEEDINGS OF THE AMERICAN ACADEMY. 



a high magnetizing field. Besides, it is probable that the iron of this 

 particular rod, which was not of the usual Bessemer steel, is not very 

 homogeneous. In such cases it has been the experience of men who 

 have had much to do with magnetization of iron in a practical way — 

 as, for instance, Mr. Thompson, the mechanic of the Jefferson Physical 



10 15 20 



Figure 11. [Tables VII and VIIL] 



Step and reversal magnetization curves for a Bessemer soft steel rod of diam- 

 eter 0.3175 cm. 



Laboratory — that heating the iron specimen white hot and then 

 allowing it to cool slowly will not get rid of the consequent poles. 

 Nor will subjecting the iron to higher magnetizing fields, and then 

 decreasing the field while reversing constantly, so as to demagnetize, 

 help the matter, for the poles come back straightway in their old 

 positions. 



After this the iron rods used in the long solenoid were carefully tested 



