292 PROCEEDINGS OF THE AMERICAN ACADEMY. 



resulting induced electromotive force in the secondary circuit, be 

 plotted, a curve of the same period as /j is obtained. This e. m. f. 

 curve is shown at A' in Figure 14. 



If, now, the ordinates of the e. m. f. curve be multiplied by the corre- 

 sponding values of the secondary current, a quantity proportional to 

 the instantaneous rate at which energy is being transferred to the sec- 



FlGURE 14. 



7i . . . . . Primary Discharge Wave. 



I2 Secondary Wave. 



E Electromotive Force due to 7i. 



W Power Delivered to Secondary Circuit. 



ondary is obtained, and if plotted, gives the curve marked TT^ in Figure 

 14. The portions of the curve below the axis of time are negative, 

 and represent a return of energy to the primary circuit. The algebraic 

 sum of the areas under the four loops is proportional to the total 

 energy permanently delivered to the secondary circuit in one cycle. 

 It is apparent that very little energy is returned to the primary circuit, 

 and that the second half of the primary loop gives the greater amount 

 of energy to the secondary circuit, the first part of the primary dis- 

 charge being more or less irregular on account of the sudden breaking 

 down of the high initial gap resistance and the superposed higher 

 harmonies resulting from the sudden shock to the system. 



In Part I it was stated that the primary current loops occur every 

 two or more secondary oscillations. In this case the primary wave, 



