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Show Engineers Harness Sun For Telephone Line The sun ultimate source of all the power which man has at his disposal began furnishing power directly to a telephone line this week for the first time. Announcement was made here by Axel A. Birch, manager, of Mountain States Telephone. Engineers switched solar power into a new type rural' telephone system Tuesday using the Bell Solar Battery, an invention of Bell Telephone Laboratories announced last year. Use of solar power is a part of experiments being conducted con-ducted near Americus, Georgia, 135 miles south of Atlanta, to develop de-velop more and better rural telephone tele-phone service. George L. Mathews, a cotton and peanut farmer, made the first call and remarked that it sounded "just fine." The Bell Solar Battery is the first successful device to convert the sun's energy directly and efficiently ef-ficiently into substantial amounts of electricity. It is at least fifteen times more efficient than the best previous solar energy converters. Excess current from the solar unit not needed for immediate telephone use feeds into a storage battery which provides power at night and over periods of bad weather. The solar battery has no moving parts of corrosive chemicals and therefore should last indefinitely. Even in poor light, it will continue to charge the storage batterly but at lower power. The telephone system, under trial at Americus, uses transistors instead of traditional vacuum tubes. The transistor, invented by Bell Laboratories and announced seven years ago, requires only small amounts' of power. The new system uses the "carrier" "car-rier" principle which allows several sev-eral conversations to be sent simultaneously sim-ultaneously over a single pair of wires. Since each conversation is sent at a different frequency, they do not interfere with each other. Multifrequency transmission has been used for years with vacuum tubes on longer distance calls. The system on trial at Americus, however, operates economically over shorter distances such as those on rural telephone lines. |