Abstracts of Bell System Technical Papers Not Appearing in the Bell System Technical Journal (01 April 1924)

Physical Review, II, Vol. XXIII, p. 265, 1924. Presented to the Institute of Radio Engineers, January 16, 1924, at New York, 347 348 BELL SYSTEM TECHNICAL JOURNAL Measuring Methods for Maintaining the Transmission Efficiency of Telephone CircuitsF. H . BEST. The circuits involved in the transmission of speech in a modern telephone plant, particularly those designed for long distance operation, necessarily involve a considerable amount of complexity. 

The use of telephone repeaters the development of long toll cables, the application of carrier systems and other developments associated with these, while increasing the efficiency and economy of telephone toll circuits have also increased their complexity and have required the development of more effective means of insuring that the circuits are maintained at all times in good condition and adjustment. Maintenance of the transmission efficiency of the telephone plant is conducted by a special force, using methods and apparatus that have been developed for this purpose. 

This paper gives a brief description of the transmission characteristics of some of the common type of telephone circuits, outlines a general method for measuring their transmission efficiency and describes several of the most modern types of transmission measuring sets, together with a brief, mention of the oscillators which supply the power for testing. A Primary Standard of Light Following the Proposal of Waidner and Burgess. HERBERT E . IVES. The primary standard of light proposed in this paper consists of a black body constructed of platinum; the light from which, at its melting point, constitutes the photometric fixed point desired.