Frequency of Electrical Oscillations. 361 



ondary of which S, had a resistance of 2000 ohms and a self 

 induction of 47*64 Henrys. The number of turns of S was 

 23 "TOO. A was a choking coil of 3200 ohms resistance and a 

 self induction of 34*84 Henrys. B was a spark gap and C a 

 condenser formed of metallic plates 8x10 inches, which were 

 immersed in castor oil at a distance of half an inch from each 

 other. The capacity of the oil condenser was 6500 electro- 

 static units. Since the circuits a, b< c, d and a, h, S A are 

 two circuits through which electrical oscillations can surge and 

 since they have very different values of L and C, formula 

 (1) t = 2tt ^/LC indicates that the frequency of oscillation in 

 the one is quite different from that in the other. Since the 

 oscillations of both circuits must vibrate between the termi- 

 nals at B it would seem that the photographic image of the 

 spark at B would be made up of these two sets of oscillations. 

 Obtaining the value of t for the circuit a, b, c, d from eq. (1) 

 we find it to be exactly equal to that obtained from a study of 

 the photograph of the spark at B. There are, undoubtedly, 

 oscillations also in the circuit a, 5, S, A. The large capacity 

 C and the great self induction of A and S however make the 

 value of t in eq. 1 very large for this circuit. So large that in 

 the case under consideration the oscillations are even fewer 

 than the impulses of the generator in the circuit a, o, S, A. 

 Indeed it is impossible to force oscillations through a compara- 

 tively small self induction without making t comparatively 

 large. 



Fig. 2 shows another arrangement of apparatus. A second 

 transformer has been added, through the transformer of which 



it has attempted to force the oscillations of the spark at B. 

 The spark gap was placed in a very strong magnetic field. 

 The transformer was a copy of that described by Mr. Tesla.* 

 The secondary S' of this transformer was wound in two 

 parts with 260 turns in each part, the whole resistance be- 

 ing 24 ohms. The wire was heavily insulated with gutta 

 percha and there was no iron core. The self induction did 

 not exceed 001 Henry. Owing to the self induction of P' 

 the time of oscillation in the circuit enclosing P', C, and B was 

 large — a few thousandths of a second. If the circuit composed 



* Experiments with alternating currents of high frequency and high potential, 

 pp. 15-17. 



