420 PROCEEDINGS OF THE AMERICAN ACADEMY. 



X = 1/t = pjl, time-constant-reciprocal of an o. c. circuit 



(seconds ~^). 

 f/j) Initial vector amplitude of the discharging p. d. in an o. c. 



circuit (volts Z ). 

 U = Uq/V^, the r. m. s. value of the initial vector discharging 



p. d. (volts). 

 f/g Initial discharging p. d. in a circuit (volts). 



u, u, Undamped and damped time-values of condenser p. d. in an 



o. c. circuit (volts), 

 Uf, Uf Undamped and damped time-values of the component of 



the condenser p. d. in phase with the current (volts). 

 T'o, F, XI Initial, r. m. s., and instantaneous values of any oscillating 



quantity, pertaining to an o. c. circuit. 

 W^ Initial energy in a condenser or in a reactance (joules). 



Wi Initial vector amplitude of cyclic energy in reactance, mn, 



Figure 7, MN, Figures 12 and 14 (joules). 

 Wfn Undamped maximum cyclic value of energy in a condenser 



or reactance (joules). 

 IV, w Undamped and damped time-values of energy in condenser 



or reactance (joules). 

 Wi Energy dissipated in a circuit in the first energy cycle 



(joules). 

 Wc, Wi Energy in a condenser, and in a reactance, at a specified 



time (joules). 

 Wi Total expenditure of energy hy dissipation from a circuit 



up to t seconds (joules). 

 Wq Energy of charge communicated to a series of condensers 



(joules). 

 Wg Semi-system energy at time t (joules). 



XX, YY Cartesian rectangular coordinates. 

 Xi, Xc Reactance of an inductance and of a condenser in an o. c. 



circuit (ohms). 

 Y Admittance of an o. c. circuit (mhos). 



Z, z Impedance of an o. c. circuit (ohms). 



Zf^,Zf^=y/ls Impedance of an o. c. circuit devoid of resistance (ohms). 

 o)(j Angular velocity of an o. c. circuit with its resistance 



ignored (circular radians per second). 

 to Angular velocity of an o. c. circuit in the presence of its 



actual resistance (circular radians per second). 

 Q Angular velocity of an ultraperiodic circuit (hyperbolic 



radians per second). 



