the High-Tension Magneto. 375 



Oscillation Measurements. 



14. The next step was to measure the constants of the 

 circuits by the methods, depending on the determination 

 of the periods of the oscillations, described in the previous 

 part of the paper. Such measurements were made on the 

 following combinations :— 10,000/0, 8000/2000, 8000/6000, 

 6000/4000, 6000/8000. The results are given in Table II., 

 the figures derived from Table 1. being given in brackets 

 where they are available. The self-inductance of the 

 primary is assumed to be independent of the uncoupled 



Table II. 



Combination. ~L X (henry). L 2 ' (henry). C 2 (mmf.).* c. 



10000/0 -00623 (-00664) 28-2(28-6) 43*5 0040 



8000/2000 -00599 (-00691) 23-3(24-4) 52 0-062 (-106) 



8000/6000 -00591 (-00691) — (36-5) — 0*360 (-378) 



6000/4000 -00573 (-00688) 19-0(18-25) 45 0-271 ('373) 



6000/8000 -00552 (-00688) — (35-8) — 0760 (-663) 



* Calculated from T 2 , assuming L 2 =L 2 '. 



secondary turns in series, while the secondary self-inductance 

 is taken to be the sum of those for the coupled and uncoupled 

 turns which are in series. The values of c in brackets are 

 calculated in this manner. It is assumed that the coupling 

 and the value of s for armatures 1, 2, 3, when there are no 

 uncoupled turns in series, are the same and equal to that 

 determined by the oscillation method for No. 1. Since 

 both s and k 2 are nearly 1, the precise choice of their values 

 will make little difference. The coupling of any other 

 combination will then bear to the coupling of 10,000/0 the 

 ratio of the self-inductance of the coupled turns to that 

 of the coupled and uncoupled turns in series. 



The agreement between the secondary self-inductances 

 determined by the two methods is within the limits of 

 experimental error ; it is certainly surprising that this 

 quantity does not vary more rapidly with the frequency. 

 On the other hand, the primary self-inductances are smaller 

 (as would be anticipated) when determined by the oscillation 

 method at the higher frequency. In the previous part 

 it was noted that Lj appeared to increase with the period of 



