Contributors to this Issue 



Akthur C. Keller. B.S., Cooper riiiou, 1923; M.S., Yale I'liiversity, 

 1925; E.E., Cooper Union, 1920; Columbia University, 1920-30; Western 

 Electric Company, 1917-25; Bell Telephone Laboratories, 1925-. Special 

 Apparatus Development Engineer, 1943; Switching Apparatus Develop- 

 ment Engineer, 1946; Assistant Director of Switching Apparatus De- 

 velopment, 1949; Director of Switching Apparatus Development, 1949-. 

 Mr. Keller's experience in the Bell System includes development and de- 

 sign of telephone instruments ; development of systems and apparatus for 

 recording and reproducing sound; and, during World War II, the de- 

 A'elopment, design, and preparation for manufacture of sonar systems 

 and apparatus. His department, in addition to being responsible for a 

 numl^er of military projects, is responsible for the fundamental studies of 

 switching apparatus and the development, design, and preparation for 

 manufacture of electromagnetic and electromechanical switching appara- 

 tus for telephone systems. Member of the American Physical Society, 

 A.I.E.E., Acoustical Society of America, I.R.E., S.M.P.T.E., and 

 the Yale Engineering Association. Representative for Bell Telephone 

 Laboratories in the Society for Experimental Stress Analysis. For his 

 contributions to the Navy during World War II, he received awards 

 from the Bureau of Ships and the Bureau of Ordanance. 



Mason A. Logan, B.S. in Physics and Engineering, California Insti- 

 tute of Technology, 1927; M.A. in Physics, Columbia University, 1933; 

 Bell Telephone Laboratories, 1927-. His early Laboratories' projects were 

 concerned with wire transmission problems particularly those of circuits, 

 noise and cross induction in local, manual and dial telephone circuits. 

 This was followed b}^ circuit research on alternating current methods of 

 signaling including the use of non-linear elements and electronic terminal 

 equipment. From 1941 to 1948 he worked on military projects, including 

 a mine fire control system, anti-aircraft gun director, magnetic proxim- 

 ity fuses, and guided missiles. For the past Hxe years he has been a 

 member of the SAvitching Apparatus Development Department in which 

 he is supervising a group concerned with static and dynamic behavior of 



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