660 



Mr. C. G. Blirkla on the Velocity of 



Then the primary and secondary circuits, as shown in fig. 4, 

 were made of approximately the same dimensions as those of 



Fig-. 4. 



B B, 



B'B', 



b R 

 z' 



the first arrangement when tuned as described. The exact 

 length of the secondary circuit giving the maximum intensity 

 of oscillation was finally obtained by the method of moving 

 the end bridge KK'. As the position of KK' was obtained 

 more accurately the wires were cut down, so that when the 

 final adjustments were made there was neither disturbing 

 capacity nor a third circuit whose oscillations would interfere 

 with those of the secondary. The circuit KBjBj'K' then 

 possessed the same natural period as that of the circuit 

 SBB'S', its length being exactly one wave-length. 



As the only change made in the system throughout a 

 series of experiments was that of changing the wires of the 

 secondary circuit KBjB/K', it was necessary to ascertain 

 the magnitude of its effect on the period of the primary, and 

 if at all appreciable to measure and allow for it. 



To do this another circuit was placed near the primary with 

 the terminal bridge B 2 B 2 ' on the side of BB' away from B 1 B 1 / 

 and with the parallel wires leading in another direction. A 

 rough experiment showed that the presence of this circuit did 

 not affect the tuning of the initial secondary by an amount 

 that could be detected. 



The effect was also shown to be quite negligible by altering 

 the distance between the bridges BB' and BiB/ of the two 

 circuits. At about "4 cm. apart sparking just did not occur 

 across from one bridge to the other, while at 8 cm. apart the 

 intensity of the induced oscillations was just sufficient to 

 enable one to tune with accuracy. This variation in the 

 distance between the circuits was made several times, and 



