TELEPHONE DIAPHRAGMS. 



459 



TABLE VI. 



Temperature Effect on Receiver Characteristics. 



Effect of Variations in Air-Chamber between Cap and 



Diaphragm. 



In order to ascertain the influence of the air-chamber over the 

 diaphragm of the ordinary receiver, a special cap was used, in which 

 this air-chamber could be varied, by altering the position of a friction- 

 tight cylindrical plug, of the same diameter as the clamping circle. 

 Motional-impedance circles were observed under these different condi- 

 tions, with the results given in the following Table: — 



TABLE VII. 



Results of Motional-Impedance Circles with Changes in Cap Air- 

 Chamber. 



