generated in a High-tension Magneto. 



167 



In the experiment the primary condenser was of capacity 

 C! = 0*2 mfd. — rather greater than that of the condenser 

 attached to the armature; and taking L x = 0*0135 henry, 

 5=1*05, we find P = 0*959. This value of the coupling- 

 is greater than that found by the other methods ; but when 

 we remember the difference in the circumstances of the 

 experiments, and especially in the value of the current, 

 it is probably not inconsistent with them. 



A similar photograph was obtained with a primary capacity 

 of 1 microfarad, and the frequency in this case was about 

 7300 per second. The ratio of the two frequencies is about 

 2*16, which is not far from the inverse ratio of the square 

 roots of the capacities, i. e. *Jb. 



Fig. 10 was obtained at the interruption of a weaker 

 primary current, in this case about 1*0 ampere. In this 

 photograph the bands are much more clearly separated, 

 reminding one rather of a "multiple spark" than of a 

 "pulsating arc." As already remarked, this effect arises 

 from the large capacity of the secondary coil. 



8. Calculation of the Maximum Secondary Potential from 

 the Constants of the Circuits. 



We can now calculate the frequencies, amplitudes, and 

 damping factors of the oscillations of the magneto circuits, 

 and hence the maximum secondary potential. 



The capacity of the condenser attached to the armature is 

 Ci=0 - 175 microfarad, and with 1^ = 0*0135 henry we have 



L 1 C 1 = 2*36.10- 9 c.g.s. 



Also L 2 C 2 = 1-48 . 10~ 9 „ 



L 21 = 0*49 henry, 

 P = 0*8, 

 s = 1*05, 



fe = 1815 > 



k = ll0 °- 



Hence, by (15), the frequencies are 



n ] = 2607 per second, 

 n 2 = 11624 



