Piijpin — Resonance Analysis of Alternating Currents. 475 



the full excitation. To bring the readings of the resonant 

 rises of potential within the scale of the multicellular voltmeter 

 at these low excitations the number of turns in the air-core 

 transformer was suitably increased. Within all these limits 

 of excitation hoth the fundamental and the harmonic increased 

 at the same rate and proportionally to the magnetization 

 of the transformer core. This magnetization extended between 

 about 600 and 4000 C.G.S. lines of force per square centimeter. 



2d Series. — To determine whether the presence of the 

 harmonic was due to the action of the transformer or to that 

 of the alternator the transformer was disconnected from the 

 alternator and two series of incandescent lamps, connected in 

 parallel, were substituted in its place. Each series consisted of 

 13 twenty-four candle power lamps. The resonator with its 

 air-core transformer remained in circuit as before. First one 

 series of lamps was placed in circuit. The rise due to the 

 fundamental was stronger than in the preceding experiments, 

 but that due to the harmonic was exceedingly faint. When 

 both series of lamps were thrown in the harmonic appeared a 

 trifle stronger but still veiy weak. Hence the inference, that 

 the harmonic was due almost exclusively to the action of the 

 transformer. 



It should be observed here that the alternator armature, 

 though well laminated, runs fairly hot in a short time, hence 

 it must be the seat of a decidedly strong hysteretic action. 

 On the other hand the transformer does not heat nearly as 

 much as the alternator armature and yet its action produces 

 the harmonic. * This certainly seems to speak strongly against 

 the view that harmonics are due to hysteresis. Other evi- 

 dences against this view will be given below. 



3d Series. — A series of experiments with open magnetic 

 circuit transformers of induction coil type in place of the lamps 

 showed the harmonic much stronger than the lamps did, but 

 considerably weaker than the experiments with the transformer 

 with closed magnetic circuit. Accurate numerical comparisons 

 between the two types of transformers in this respect was not 

 attempted. It sufficed to establish that, closed magnetic cir- 

 cuit transformers distort the primary current considerably 

 more than transformers with open magnetic circuits under 

 equal degrees of magnetization • on the other hand, in the 

 first case the distortion is confined almost entirely to the pri- 

 mary circuit when the secondary is closed by a non-self-induc- 

 tive resistance, whereas in the second case it is felt in the 

 secondary circuit also, though considerably less than in the 

 primary. 



