Contributors to this Issue 



Elizabeth J. Armstrong, M.A. in Geology, Bryn Mawr College, 1934; 

 Ph.D., 1939. Lecturer in Geolog}^ Barnard College, 1938-41; Research 

 Assistant, Columbia University 1941-42; National Research Council Fel- 

 low, 1942-43; Bell Telephone Laboratories, 1943-. Recently Miss Arm- 

 strong has been working on X-ray studies of crs'stal strain and imperfections. 

 X-ray irradiation and twinning. 



J. L. Clarke, B.Sc. in Electrical Engineering, University of London, 

 1909. Bell Telephone Company of Canada. 19. 0-; Transmission Engineer, 

 1924- . 



John W. Clark, A.B., University of Montana, 1935; M.S., University of 

 of Illinois, 1937; Ph.D., 1939. Dr. Clark joined the Technical Staflf of the 

 Bell Telephone Laboratories in 1939, where his principal interest has been 

 in the development of vacuum tubes for use at ultra-high frequencies. 



WiLLL\M H. C. HiGCiNS, Purdue University, B.S. 1929; E.E. 1934. De- 

 velopment and Research Department, American Telephone and Telegraph 

 Company, 1929-34; Bell Telephone Laboratories, 1934-. During his em- 

 ployment with the A. T. & T. Company Mr. Higgins was engaged in carrier 

 telephone and program transmission studies. Since his tranfer to Bell 

 Telephone Laboratories he had been concerned with radio and radar de- 

 velopment. 



Kent>:eth S. Johnson, A.B., Harv^ard University, 1907; Harvard Graduate 

 School of Applied Science, 1907-09. Transmission and Protection De- 

 partment, American Telephone and Telegraph Company, 1909-13; En- 

 gineering Department, Western Electric Company, 1913-25; Bell Telephone 

 Laboratories, 1925-. Formerly as Transmission Research Engineer and 

 now as Transmission Standards Engineer, Mr. Johnson has long been en- 

 gaged in work closely connected with all types of transmission network prob- 

 lems. He is the author of the book "Transmission Circuits for Telephonic 

 Communication." 



John Leutritz, B.S. in Chemistry, Bowdoin College, 1929; A. M. in 

 Botany, Columbia University, 1934; Ph.D., Columbia University, 1945. 

 U. S. Navy, Medical Corps, 1921-25. Bell Telephone Laboratories, 1929-. 

 Mr. Leutritz' interest has been along biological lines, primarily in respect 



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