10 



KENNELLY AND KUROKAWA. 



be set at any desired position within it, by means of the projecting 

 brass rod r. The telephone receiver R is clamped, by means of a 

 metallic strip, on to a wooden pedestal rising from the base BB. 



TT 



i ■■ 



81 8 cm. 



L 'm 



jg^m 



s 



rm^ 



T 



I I 



i 



Figure 2. Side Elevation and Plan of Experimental Tube. 



The telephone receiver used in the tests here described was a bipolar 

 Western Electric Company's instrument of a well known pattern, 

 provided with a composition cap or cover. This cover had its opening 

 enlarged, as is shown in Figures 2 and 3, so as to connect more easily 

 with the acoustic tube TT. 



Figure 3. Longitudinal Section of Air Tube and Telephone Receiver 

 fastened to the Same. 



The electric impedance of the receiver was measured in the Rayleigh 

 bridge shown in Figure 4. The adjustable-frequency source S, was a 



