L56 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



rl n 



e l = 



+ h 



If, however, the resistance of the circuit at the outset had been 

 (r -|- h) and if after the final value of the current / f>r this resistance 



had been established, the 

 extra resistance had been 

 suddenly removed from the 

 circuit, the current curve 

 from that instant on would 

 have followed the equation 



It is clear, therefore, that 

 in the case of a circuit of 

 this kind the last (upper) 

 portion of a step curve of 

 the form U (Figure 4) will 

 have exactly the same sha] if 

 as the corresponding part of 

 the V curve, although the 

 lower portions may be very 

 different 



It' in the case also of a 

 circuit which has one or 

 more finely divided iron 

 cores the flux of induction 

 through the circuit can be 

 considered as a single val- 

 ued (given) function of the 

 current strength when the 

 magnetic state of the iron at the ontsel is given, the upper portion of a 

 curve of the U type (Figure 4) belonging to the circuit will be identical 

 with the corresponding part of a curve of the Ptype. We need con- 

 sider only a U curve with one intermediate step. If the induction (X) 





0.5 



Fioi i.i. BO. 



AMPERES 



.1/ is a portion of a statical hysteresis dia- 

 gram for a certain transformer under an excita- 

 tion of 1812 ampere turn-. V is a Bimilar curve 

 obtained from a reverse current oscillogram. 



