Oscillatory fluctuations (micropulsations), appearing as trains of waves in the frequency range of 1/2 to 1/32 cps, were present about 20 pct of the time, with amplitudes of 0.01γ or more, in records of the vertical component of field made at Tucson with a large buried loop in the summer of 1947. The amplitudes of the oscillations were inversely proportional to their frequencies, and 1/20‐cps oscillations occurred more often than those of other frequencies. The highest frequencies occurred at night and were related to times of large magnetic disturbance; the lowest frequencies occurred during the day at times of low or moderate activity, and the intermediate frequencies showed a transition of behavior. Random fluctuations, having no characteristic wave forms, had amplitudes which varied as the square root of the fluctuation duration. Average amplitudes of the three largest fluctuations per 15‐min scaling interval decreased from 0.08γ at 60‐sec duration to 0.01γ at one second; maximum amplitudes were about ten times these values. The random fluctuations also showed diurnal variations and a dependence on the degree of magnetic disturbance. A few audio‐frequency measurements are also reported.
The functions of the National Bureau of Standards are set forth in the Act of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards: the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to Government Agencies on scientific and technical problems; invention and development of devices to serve special needs of the Govern¬ ment; and the development of standard practices, codes and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. A major portion of the Bureau's work is performed for other Government Agencies, par¬ ticularly the Department of Defense and the Atomic Energy Commission. The scope of activities is suggested by the listing of divisions and sections on the inside back cover. Reports and Publications rhe results of the Bureau's work take the form of either actual equipment and de¬ vices or published papers and reports. Reports are issued to the sponsoring agency of a particular project or program.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.