42 KENNELLY AND KUROKAWA. 



X Displacement of a diaphragm from its quiescent position or of 



a thin layer of air in a tube from its quiescent position (rms. 

 cm.). 



X Vibrational Velocity of a diaphragm or of a thin layer of air 



in a tube (rms. cm. /sec. Z ). 



X Vibrational acceleration of a diaphragm or of a thin layer of air 



in a tube (rms. cm. /sec- Z ). 



Xm, Xm, Xm Maximum cyclic sizes of vibrational displacement, velocity and 

 acceleration (cm., kines, kines/sec). 



X, X Root mean square values of displacement and velocity taken 



over entire surface of flexible vibrating diaphragm (cm. Z , 

 kines Z ). 



Xo, Xo Root mean square values of displacement and velocity at center 



of vibrating telephone diaphragm (cm. Z , kines Z ). 



Y' = 1/Z' Electric motional admittance of telephone receiver (ohmsZ). 



y Linear admittance of electric conductor (ohms/km. Z ). 



y Linear admittance of acoustic conductor (mech. absohms/ 



cm. Z ). 

 Z, Zd Impedance of a telephone receiver, free and damped (absohms 



/). 

 Zp, TjA Impedance at point P and at sending end of electric line 



(ohms Z ) or for acoustic line (mech. absohms Z ). 



Z' = Z — Z(f Motional impedance of telephone receiver (absohms Z ) . 



Zo Maximum or diametral value of receiver motional impedance 



(absohms Z ) . 

 Zi, z-i, z Acoustic impedance on sides 1 and 2 of a diaphragm and their 



vector sum (acoustic absohms Z ). 



z' Total mechanic impedance on a diaphragm (mech. absohms Z ). 



Zd Internal mechanic impedance of a diaphragm (mech. absohms 



Z). _ 



Zj Virtual mechanic impedance of a diaphragm due to its vibra- 



tion in a permanent magnetic field (mech. absohms Z ). 



z Linear impedance of electric conductor (ohms/km.). 



Z Linear impedance of acoustic conductor (mech. absohms /cm. 



Z). 

 Zo, Zo Surge impedance of electric and acoustic conductor (ohms Z , 



mech. absohms Z ). 

 ji, ^2, J Acoustic impedance densities on sides 1 and 2 of a diaphragm, 



and their vector sum (acoustic absohms/sq. cm. Z ). 



CO = 27r/ Impressed angular velocity (radians/sec). 



Z Sign indicating a planevector quantity or complex number. 



rms Root mean square. 



ah or ahs Prefix signifying a C.G.S. unit. 



a-c Alternating-current. 



d-c Direct-current. 



