the Induction- Coil. 



713 



3 4-56 



T. ' tN THOUSANDTHS OF A SSCOA/O 



170-1, 



n =908-8, 



« = b , o amp. 



Case IV. — This differs from the last only in the use of a 

 smaller capacity in the secondary circuit, its value being 

 '0002213 microfarad. The frequencies were 



7^ = 230-2, 



= 1444-7, 



and with { = G*75 amperes the secondary potential is given 



by 



2V 2 = 32411 



-5168*- 



— i"88« 



145-6t 



sin (82888/ -0-29) 

 sin (520086*- 1-82). 



The maximum value of this expression, which occurs at 

 the second peak of the curve, is 36060 volts. The curve is 

 shown in fig. 4 (p. 714). 



Several photographs were taken for this case, and though 

 similar in their general features they differed considerably 

 from one another in detail. Sometimes the first peak was 

 equal to or higher than the second, sometimes the peak in 

 the second principal wave was higher than both maxima in the 

 first. These differences arise apparently from irregularities in 

 the working of the interrupter, which seem to affect chiefly 

 the amplitude and phase of the more rapid oscillation. The 

 photograph in Plate XII. fig. 11 shows the type which 

 occurred most frequently. By comparison with the air-core 

 coil the highest point of the curve was found to correspond 

 to a secondary (observed) potential of 27560 volts. 



