Associate Editor, Textbook Department, American School of Correspondence

ERNEST L. WALLACE, B.S.

Assistant Examiner, United States Patent Office, Washington, D. C.

GEORGE R. METCALFE, M.E.

Editor, American Institute of Electrical Engineers
Formerly Head of Publication Department, Westinghouse Elec. & Mfg. Co.

J.P. SCHROETER

Graduate, Munich Technical School
Instructor in Electrical Engineering, American School of Correspondence