644 



PROCEEDINGS OF THE AMERICAN ACADBMT. 



but made upon a phenomenally soft bar of mild steel 12 centimeters 

 long and about 2.86 centimeters in diameter. The line OEC, which is 

 nearly straight, represents the induction flux through the central cross 



Figure 5. A cylindrical shell, about 12 centimeters long and 2.8 centimeters 

 in outside diameter, was exposed in a long solenoid to exciting currents of 

 various intensities. OCL represents the flux tlirough the central cross section 

 of the cylinder when the current was running, and OPQ, drawn on a some- 

 what exaggerated scale, the remanent flux when the circuit was suddenly 

 broken. The horizontal unit corresponds to a field of 25 gausses in the sole- 

 noid when the iron was not there. 



section of the bar while the metal was under the action of the mag- 

 netizing field. Each ordinate has only one nine-hundredth of the 

 length it would have if the scale of this curve were the same as for the 

 other lines in the figure. The ordinates of OGF give the remanent 

 flux when the slowly applied exciting current was as slowly reduced to 



