70 



Mr. W. Morris Jones on the most Effective 



fourth column gives the maximum distances at which the 

 neon tube glowed. The last three values of d in each table 

 have been reduced, as explained above, by 10 per cent. The 

 distances are measures of the maximum potential that can be 

 developed in the secondary for the corresponding values of 

 k 2 and m, and a primary spark-length of 1 mm. 



The results in column 2 of the tables are plotted as curves 

 in figs. 1 and 2, in which the abscissse represent 1/k 2 and the 

 ordinates the values of m. Some of the points do not lie well 

 on the curves. This is due to the difficulty of accurately 

 adjusting the primary capacity to its optimum value. 



Fi<?. 1. 



7-00 



However, the curves show that, for all the degrees of 

 coupling obtained, LisC^/I^Cx was less than unity. It is 

 clear from these results that, if the adjustment of the Tesla 

 coil is made by varying the primary capacity alone, then the 

 optimum value of C?i is greater than the resonance value, 

 the difference between them diminishing with k 2 in accordance 

 with the theory. The tables also show that the frequency- 

 ratio n 2 /n u when the primary capacity is adjusted to the 

 optimum value, passes through 2 in the neighbourhood of 

 the value k 2 = 0*265. This is also in accordance with the 



theory. 



