Abstracts of Technical Articles by Bell System Authors (01 January 1946)

Published by D. Van Nostrand Company, Inc., New York, N. Y., 1945. 159 160 BELL SYSTEM TECHNICAL JOURNAL theory to vacuum tube circuits consists chiefly in giving special emphasis to network design problems ordinarily found as part of vacuum tube amplifier design. The design of an over-all feedback loop is, of course, an outstanding example. In addition, special attention is also given to the design of such individual network units as input and output circuits, interstage networks, and local feedback circuits, especially when they appear as constituents of a broad-band amplifier. 

Judging Mica Quality Electrically.2 K. G. COUTLEE. A threatened mica shortage resulting from an unprecedented wartime demand for mica capacitors used in electronic communication equipment by the Armed Forces was forestalled by rigid conservation measures, use of alternate materials, and the use of electrically selected mica from types previously considered unsuitable for capacitor use. By employing two electrical tests, developed by Bell Telephone Laboratories, Inc. for the War Production Board, in combination with visual and physical requirements, mica was selected from plentiful stocks of lower visual quality types of mica, effectively increasing the supply of capacitor mica by 60 per cent. This method of electrically judging the quality of raw mica was given a thorough commercial trial and found both practicable and reliable. A Simple Optical Method for the Synthesis and Evaluation of Television Images.3 R.