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U.S. Bureau of Standards

    Naturevolume 134page188 (1934) | Download Citation



    THE annual report of the U.S. Bureau of Standards for the year ended June 30, 1933, is very satisfactory, notwithstanding the industrial depression. New determinations of the values of the electrical units have been made by absolute measurements. In the case of the ohm, the inaccuracy was only of the order of about one in a million. The Bureau has fixed the visibility factors for commercial types of electric lamps by means of coloured filters. These values have been adopted internationally. A piezo-electric standard has been constructed which maintains a wave frequency constant within one part in ten million for several hours without adjustment. The accuracy of the 5,000 kilocycle radio transmissions which are disseminated periodically has been increased to one in ten million.

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