Low Temperature Coefficient Quartz Crystals. - [WAVE FILTERS]

New York, American Telephone and Telegraph Company, 1940. 8vo. Volume XIX, January, No. 1, 1940 of ""The Bell System Technical Journal"". In the original printed bluish grey wrappers. A bit of sunning to extremities, lower right corner of front wrapper slightly bent and a small tear to outer margin of front wrapper, no loss. Previous owner's name and pencil-markings to top of front wrapper. Internally clean. Pp. 74-93.

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First publication of Mason's influential paper on quartz and its use in wave filters. One of Bell System's most fundamental research tasks was to create a common communication carrier able to transmit a great many messages over a single long-distance channel such as the Transatlantic telephone cable laid down in 1957.""Precise electrical filtration is required to combine the many individual speech signals into a single, wideband signal and to separate them after transmission. The wave filters required for this trask must have high stability and frequency selectivity. In the 1940s, W. P. Mason and collaborators pioneered in the application of especially cut quartz crystals for this purpose. Their designs contributed to the economical development of wideband carriers for high-capacity telephone systems"". (Millman, A History of Engineering & Science in the Bell System, 1984, p. 108).