JPiipin — Resonance Analysis of Alternating Currents. 387 





Table 



II. 







Voltmeter readings Voltmeter readings 



Theoretical 



Resistance 



with a mica 



with a paraffin 



value of volt- 



in ohms. 



condenser. 



condenser. 



meter readings. 



38 



183 



170 



225-6 



48 



155 



148 



178-6 



53 



144 



137 



161-8 



58 



134 



128 



147-8 



63 



125 



120 



136 



68 



118 



113 



126 



78 



105 



101 



110 



88 



94 



91 



97-4 



98 



85 



83 



87-5 



108 



78 



76 



79-4 



118 



72-5 



70 



72-6 



128 



67 



65 



65-5 



138 



62 



60 



60 



The experimental data from which these curves were plotted 

 are given in Table II. Curve II was plotted from voltmeter 

 readings obtained with a mica condenser, Curve III represents 

 the corresponding readings obtained with a paraffin condenser 

 and given in the third column of Table II. Curve I repre- 

 sents the theoretical curve, that is the curve which would have 

 been obtained if the law of variation of the voltmeter readings 

 with the resistance had been the same throughout as it was at 

 low readings. On account of the damping effect due to dielec- 

 tric viscosity in the condenser a deviation from the above 

 mentioned hyperbolic relation was of course expected, but it 

 was quite a pleasant surprise to find a perfect regularity of 

 these deviations. These curves indicate a rapid increase in the 

 dielectric damping with the voltage and also the superiority of 

 mica to paraffin, especially at higher voltages. They also 

 suggest that at low voltages and frequencies over a hundred 

 periods per second this difference between the two substances 

 becomes less and less marked. It was also found in a similar 

 way that the damping effect of the magnetic viscosity of iron 

 is small at low magnetizations, such, for instance, as would be 

 produced by a telephonic current in a telephone receiver, and 

 at frequencies which are well within the range of higher tele- 

 phonic frequencies, say 750 periods per second. 



Similar curves and similar results were obtained with higher 

 harmonics. These experimental tests show, therefore, that the 

 relative values of the amplitudes of the harmonics to that of 

 the fundamental frequency are not seriously modified by the 

 dielectric damping of the condensers, especially when one 

 operates with moderate voltages as was the case in the follow- 

 ing experiments. 



Am. Jour. Sci.— Tsird Series, Vol. XLVIII, No. 28V.— Nov., 1894. 

 25 



