The Contributors to this Issue 



George A. Campbell, B.S., Massachusetts Institute of Technology, 

 1891; A.B., Harvard, 1892; Ph.D., 1901; Gottingen, Vienna and 

 Paris, 1893-96. Mechanical Department, American Bell Telephone 

 Company, 1897; Engineering Department, American Telephone and 

 Telegraph Company, 1903-1919; Department of Development and 

 Research, 1919 — ; Research Engineer, 1908 — . Dr. Campbell has 

 published papers on loading and the theory of electric circuits and is 

 also well-known to telephone engineers for his contributions to re- 

 peater and substation circuits. The electric filter which is one of his 

 inventions plays a fundamental role in telephone repeater, carrier 

 current and radio systems. 



Ralph V. L. Hartley, A.B., Utah, 1909; B.A., Oxford, 1912; 

 B.Sc, 1913; instructor in physics, Nevada, 1909-10; Engineering 

 Department, Western Electric Company, 1913 — . For some time 

 Mr. Hartley has been closely connected with the development of 

 carrier current, telephone repeater, and telegraph systems. 



Thornton C. Fry, A.B., Findlay, 1912; A.M., University of Wis- 

 consin, 1913; Ph.D., 1920; instructor of mathematics, Wisconsin, 

 1912-16; Engineering Department, Western Electric Company, 

 1916 — . Mr. Fry has written several papers on the theory of electric 

 circuits and other subjects allied to telephony. 



John R. Carson, B.S., Princeton, 1907; E.E., 1909; M.S., 1912; 

 Research Department, Westinghouse Electric and Manufacturing 

 Company; 1910-12; instructor of physics and electrical engineering, 

 Princeton, 1912-14; American Telephone and Telegraph Company, 

 Engineering Department, 1914-15; Patent Department, 1916-17; 

 Engineering Department, 1918; Department of Development and 

 Research, 1919 — . Mr. Carson's work has been along theoretical lines 

 and he has published several papers on theory of electric circuits and 

 electric wave propagation. 



R. L. Wegel, A.B., Ripon College, 1910; assistant in physics, 

 University of Wisconsin, 1910-12; physicist with T. A. Edison, 1912- 

 13; Engineering Department of Western Electric Company, 1914 — . 

 Mr. Wegel has been. closely associated with the development of tele- 

 phone transmitters and receivers, and has made important contribu- 

 tions to the theory of receivers. 



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