416 



KENNELLY, TAYLOR— PROPERTIES OF 



1. Investigations were made with a view to ascertaining how 

 the two lag angles, /?i° and (3o° compared with each other, in a given 

 receiver, and to what extent they depended upon the impressed fre- 

 quency and upon variations in construction. 



2. In the course of this research, which has involved the obser- 

 vation and plotting of some sixty motional-impedance circles, cer- 

 tain departures from the circle were noted, due to abnormalities or 

 irregularities in the mechanics of the receiver diaphragm under test. 

 Investigation was directed towards determining the nature and 

 causes of these departures. 



I. Investigation of the Depression Angles /?i° and /Jo". 



The method adopted for investigating the magnitudes of the 

 two component depression angles ^^'^ and (3.° was an optical one, 

 involving Lissajous figures.^ A small and powerful beam of hght 



Telephone 

 Receiver 



Kxpioring mirror 

 supported so as to 

 vibrate onhoriiontal 

 axis 



Arc Lomp 



Duddell 

 Vibration 



Caivanomettrr 



To Rayleigh Bridge 

 and Vreeland QiciWator 



Fig. I. Diagram of Optical System for Producing Lissajous' Figures. 



from an arc lamp, A, Fig. i, was directed onto a tiny triangular ex- 

 ploring mirror, about 0.5 mm. in length of edge m, as referred to 

 in both of the preceding papers of this research.* This mirror was 

 elastically supported in contact with the center of the outer surface 

 of the telephone diaphragm D, so that vibratory displacements of 

 the latter would cause the mirror, in, to rock about a horizontal 



3 Bibliography, i. 



4 Bibliography, 9 and 10. 



