PEIRCE. 



MANNER OP GROWTH OF A CURRENT. 



539 



the ordinates of the curve (2) which represents the current in the sec- 

 ondary, are on an arbitrary scale. If at the time t = 0, the main circuit 

 through which a steady current of 3.12 amperes had been passing were 

 suddenly broken, the current in the secondary would have grown and 

 died out after the manner indicated by the dotted curve (3). For about 

 half a second after the main circuit was interrupted, there would have 

 been no sensible current in the secondary, but then it would have sud- 

 denly appeared in a manner that strongly suggests the theoretical curves 

 shown in Figures 6 and 8. Figure 22 illustrates the fact that the form 

 of the secondary current curve depends very much upon the intensity of 

 u 



Figuue 23. 



the current in the main circuit, and that sometimes a comparatively slight 

 change in the latter will alter materially the maximum intensity of the 

 secondary current. The diagram is a careful reproduction of the records 

 of the secondary oscillograph for currents of 3.76 amperes, 3.12 amperes, 

 and 2.60 amperes respectively. The scale at the bottom represents sec- 

 onds ; the records, which are to be read from right to left, are displaced 

 with respect to each other merely to prevent confusion in the figure. 



The lag in seconds of the crest of the current in the secondary circuit 

 behind the closing of the main circuit depends, naturally enough, upon 

 the final intensity of the main current and upon the magnetic condition 

 of the core at the outset. If a series of currents of the same final inten- 

 sity be passed first in one direction and then in the other through the 

 main coil, and if after the circuit has been broken for half a minute the 



