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PROCEEDINGS OF THE AMERICAN ACADEMY. 



Figure 13 gives two curves, the first, OKED, belonging to a shell of 

 diameters 2.83 and 1.93, with a core of diameter 1.60 centimeters ; the 

 second, OGPQ, to a shell of diameters 3.20 and 2.20, with a core of 

 diameter 1.90. In each of these cases the residual magnetism is re- 

 versed in sign for comparatively small currents, then direct for currents 



Figure 13. The ordinates of each of the curves of Figure 13 show the 

 remanent magnetism in a combination of a soft Bessemer shell and core when 

 the slowly applied exciting current has been suddenly broken. A negative 

 ordinate indicates that the residual magnetism has a sign opposite to that 

 of the field in the solenoid when the current was running. 



somewhat stronger, and for large currents is again reversed with no 

 apparent desire to become again positive. Curve LMNZ of Figure 14 

 belongs to a shell of diameters 2.83 and 1.93 with a core of diameter 

 1.90. The gap between core and shell is here narrower than in the 

 cases just mentioned, and the curve which gives the magnitude of 

 the residual magnetization in terms of the exciting current, while of 

 the same general form as those of Figure 13, does not cross the axis of 

 abscissas, and the residual moment is reversed for all the excitations 

 shown in the curve. 



