74 Most Effective Primary Capacity for Tesla Coils. 



maximum secondary potential, since V , L 21 , and L x are 

 constant during the experiment. The frequency-ratio r? 2 A*i 

 is calculated from the relation 



^2 

 2 



vi + 1 + y{(m-l) 2 + 4Pm} 



n x 2 m+l-y/{(m-iy + Mrm} 



There are important differences between the experimental 

 and theoretical curves, figs. 5 and 6. The theoretical greatest 

 maximum occurs at about m = 0*l, and corresponds approxi- 

 mately to the frequency-ratio n 2 /n l = 4. This does not appear 

 at all in the experimental curve, in which also the maximum 

 shown occurs at a smaller value of m than does the secondary 

 maximum in the theoretical curve. 



It should be remembered, however, that in the expression 

 (1) for the secondary potential, damping due to all causes 

 is neglected, and that the theoretical curve of fig. 6 

 represents only those maxima which occur near the time 



l/fth; 



It is possible that in the experiment the damping might be 

 so great in some cases as to diminish these maxima, so that 

 they would not appear as such in the experimental curve. 

 Possibly also the continuation of the experimental curve 

 (fig. 5) to smaller values of m would have revealed some 

 trace of another maximum. 



Time did not allow me to determine and allow for the 

 damping factors of the oscillations. With these taken into 

 account better agreement would probably have been found 

 between the curves of figs. 5 and 6. 



Similar curves were obtained for the case k 2 = 0*255 and. 

 the primary at the lower end of the secondary, and the 

 experimental and calculated curves showed differences similar 

 to those of figs. 5 and 6. 



The above experiments were carried out in the Physical 

 Laboratory of the University College of North Wales ; and 

 in conclusion, I desire to record my obligation to Professor 

 E. Taylor Jones for bringing the subject of the above 

 investigation to my notice and for much valuable help and 

 advice during its progress. 



