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BRLL SYSTEM TECHNICAL JOURNAL 



volved more than the mounting of the available types of transmitters 

 and receivers on a common handle and that considerable development 

 of the instruments as well as the means for coupling them would be 

 required before a handset suitable for general use were obtained. For 

 this reason, the telephone system in this country has in general been 

 built up around the wall set and the deskstand which permitted the 

 utilization of the available transmitters and receivers to best ad- 

 vantage. 





Fig. 1 — Operators handset used in 1878. 



A number of factors contribute to the difficulties involved in the 

 design of a handset which gives as good service performance as a desk- 

 stand. Some of these are due to a difference in the conditions of use 

 of the two instruments and some are due to the necessary differences 

 in structure. A consideration of these differences will afford a back- 

 ground for the subsequent description of the line of attack followed in 

 providing a satisfactory handset. 



Difference in Usage 

 The controlling differences in service conditions are due to the fact 

 that the handset permits the user much more freedom than the desk- 



