384 JPupin — Resonance Analysis of Alternating Currents. 



curve. The vertical row denotes the voltmeter readings in 

 volts. Consider now the two-peaked curve. It expresses the 

 law of variation of the voltmeter readings when the capacity 

 of the resonator circuit is varied from to 2 microfarads, the 

 self-induction being kept constant. The readings are recorded 

 in Table 1. 



Table I. 



Capacity of the condenser 



Voltmeter readings 



in microfarads. 



in volts. 



•18 



62 



•181 



68 



•182 



73-5 



•183 



79 



•184 



89 



•185 



96 



•186 



104 



■187 



110 



•188 



120 



•189 



126 



•190 



127 



•191 



125 



•194 



99 



•198 



71 



•202 



very low 



1-65 



69 



1-70 



89 



1-75 



120 



1-80 



146 



1-808 



146 



1-817 



145 



1-897 



96 



1-976 



60 



The voltmeter emploj^ed in these experiments was a Sir Wil- 

 liam Thomson's multicellular voltmeter with a range from 60 

 to 240 volts. The curve was obtained from a 10 H. P. Fort 

 Wayne 8 pole alternator with a smooth core armature feeding 

 a 5 K. W. Stanley transformer (closed magnetic circuit), the 

 secondary circuit being open. It is seen that resonance took 

 place at : 190 M. F. and 1-8 M. F. The capacity of the inertia 

 coil </, fig. l b and of the voltmeter as gathered from all experi- 

 mental data was about '011 M. F., so that the real capacities at 

 which resonance took place were "201 M. F. and- 1*81 M. F., 

 that is in a ratio to each other as 1 : 3 2 . It will be seen, how- 

 ever, that a very accurate knowledge of capacity is not required 

 in the experiments described in this paper. 



The frequencies detected by the two-peaked curve, which I 

 shall call the resonance diagram, were therefore the funda- 



