516 31. I. Pupin — Electrical Oscillations of 



critical pointy the rise of potential due to resonance fell off 

 gradually until the iron wire bundle was entirely removed. 

 It is very instructive to observe that the position of the critical 

 point changes perceptibly with the amplitude of the impressed 

 e. m. force. 



It is evident, of course, that on account of hysteresis losses 

 the rise of potential produced by resonance will be less than 

 the theoretical value given by (15). And the first explanation 

 which one will naturally offer for the above discrepancy 

 between the theoretical and the actual value will be that as the 

 quantity of iron wire in the interia coil is increased the increase 

 of the coefficient of self-induction tends to increase the reso- 

 nant rise but that on the other hand the increase of hysteresis 

 losses due to the increased mass of iron tends to pull this rise 

 down and that it is then simply a question of adjustment 

 which one of the two tendencies will predominate. This 

 explanation does not, however, cover the ground completely 

 as will be found by the following experiments : 



Experiment 3. — In order to experiment with lower frequen- 

 cies, as they seemed to bring out this peculiar behavior of the 

 iron more clearly, I substituted a one H. P. four-pole alter- 

 nator for the large alternator. The speed was such as to give 

 the impressed e. m. f. a frequency of 50 periods per second. 







Table 



III. 







Part A. 



Fart B. 



Part C 





Capacity 



in 



10- 6 Farads. 



Voltage 



of the 



condenser. 



Capacity 



in 



10- 6 Farads. 



Voltage 



of the 



condenser. 



Capacity 



in 



10- 6 Farads. 



Voltage 



of the 



condenser. 



o-o 



32- 



o-o 



32- 



o-o 



32' 



0-5 



32-5 



0-5 



33-5 



1-9 



32-5 



1-0 



34- 



i-o 



34-5 



4-9 



35- 



19 



36- 



1-9 



37- 



6 1 



36' 



4-1 



39' 



4-1 



42' 



7-9 



37- 



4-9 



4V 



4-9 



52- 



iro 



38- 



6-1 



51- 



6-1 



62-5 



12-9 



39-5 



7-0 



62-5 



7-0 



77- 



15-9 



42' 



7-9 



77*5 



7-9 



97- 



18-9 



44- 



8-2 



79- 



8-2 



100- 



21-1 



46- 



9-1 



97- 



11-0 



130- 







11-0 



120- 



11-5 



122-5 







12-4 



111- 



11-9 



112" 







12-9 



103- 



13-9 



94- 







15-9 



65- 



14M 



77- 







18-9 



45- 



15-9 

 18-9 



57- 

 41- 







