Contributors to this Issue 



Karl K. Darrow, B.S., University of Chicago, 1911; University of 

 Paris, 1911-12; University of Berlin, 1912; Ph.D., University of 

 Chicago, 1917. Western Electric Company, 1917-25; Bell Telephone 

 Laboratories, 1925-. Dr. Darrow has been engaged largely in writing 

 on various fields of physics and the allied sciences. 



Lloyd Espenschied. Mr. Espenschied is High Frequency Trans- 

 mission Development Director in the Bell Telephone Laboratories. 

 He joined the Bell System in 1910, having graduated from Pratt 

 Institute the previous year. He has taken an important part in prac- 

 tically all of the Bell System radio developments, beginning with the 

 first long-distance radio-telephone tests of 1915, at which time he re- 

 ceived the voice in Hawaii from Arlington, Virginia. He has partici- 

 pated in a number of international conferences on electric communica- 

 tions. 



J. G. Kreer, B.S. in Electrical Engineering, University of Illinois, 

 1925 ; M.A., Columbia University, 1928. Bell Telephone Laboratories, 

 1925-. Mr. Kreer has been engaged in research work on carrier fre- 

 quency systems. 



S. A. Levin, E.E., Chalmers Technical Institute, Gothenburg, 1919; 

 Technische Hochschule, Berlin, 1920-21; Technische Hochschule, 

 Dresden, 1921-23. Radio Department, General Electric Company, 

 Schenectady, N. Y., 1923-26; Engineering Department, National 

 Electric Light Association, New York, N. Y., 1926-30. Bell Telephone 

 Laboratories, 1930-. Mr. Levin's work has to do with the develop- 

 ment of high-frequency measuring equipment for carrier systems. 



G. L. Pearson, A.B., Willamette University, 1926; M.A. Stanford 

 University, 1929. Bell Telephone Laboratories, 1929-. Mr. Pearson 

 has been engaged in a study of the noise inherent in electric circuits. 



D. B. Penick, B.S. in Electrical Engineering, University of Texas, 

 1923; B.A., 1924; M.A. in Physics, Columbia University, 1927. West- 

 ern Electric Company, Engineering Department, 1924-25; Bell Tele- 

 phone Laboratories, 1925-. Mr. Penick has been engaged in special 

 problems related to the development of vacuum tubes. 



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