114 KENNELLY-TAYLOR— EXPLORATIONS OVER [April 22, 



ceiver was here absent. Alternating current of 2 milliamperes 

 (root-mean-square) was supplied from a Vreeland oscillator, giv- 

 ing a close approximation to a pure sine wave, and in connection 

 with a Rayleigh bridge, for the simultaneous measurement of both 

 the resistance and inductance of the telephone receiver, at 32 fre- 

 quencies varying between 429 and 2,040^. Explorations were 



ViBF^ATioN Contours 

 Diaphragm No. 2. 



made at two frequencies; one, the resonant frequency of 992 --'j 

 and the other shghtly below this, or 974 ^. The contour lines for 

 the latter case are presented in Fig. 13, where the outlines of the 



