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PROCEEDi:NrGS OF THE AMEEICAN ACADEMY. 



See Figure 14 for the original curves, from iii = 15 to m = 240, from 

 which Table XII, of January 22, 1907, was constructed. It will be seen 

 that on the figure there appear a number of crosses. These represent 

 magnetization curves, not actually drawn, which were taken with the 



TABLE X. [No Figure.] 



January 15, 1907. 

 Diam. = 0.4763 cm. = 3/16 in. 

 Step Method. Long Coil. 



reversal method. This brings out a most interesting point. The thick 

 brass tube opposes a sudden change in the magnetizing field, by virtue 

 of eddy currents, and thus the establishment of the field is somewhat 

 delayed and the magnetization of the iron takes place more slowly. 

 The step method magnetization also is slower than the step method 

 when used in a plain solenoid wound on a tube of pasteboard, as is the 



