.,.,.) 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



See Figure I l for the original curves, from m = 1"> to m = 240, from 

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

 that on tin' figure there appear a nuniher of crosses. These represent 

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



TABLE X. [No Fi.;rRE.] 



January 15. 1907. 

 Diara. = 0.4703 cm. = 3/16 in. 

 Si i.i' Mi rHOD. I. iim. Con.. 



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 current-, 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 methyl 

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



