Measures for Progress: A History of the National Bureau of Standards

292 THE TIDE OF COMMERCE AND INDUSTRY (1920-30)
Dr. I. Howard Dellinger examines the continuous recording of super-power tests of
station Schenectady. In 1926 when this picture was taken, WGY had been
granted permission to broadcast regularly twice a week on 50,000 watts. WGY as-
sisted the Bureau for a number of years in both its studies of radio interference and
its compiling of radio propagation data.
extraordinary selective, precise, and portable frequency standard both for
the use of radio inspectors and for the stations themselves. The remarkable
accuracy of about 0.01 percent attained with the oscillator closely agreed with
that of the national laboratories abroad, as comparison tests disclosed, but
it was not enough for the Bureau. Mechanical ingenuity and capital had
already created a far more acute situation in broadcasting in this country
than abroad. The Bureau therefore aimed at absolute frequency values with
a certainty of 0.001 percent. It achieved them before the decade was
Upon formal adoption by the Federal Radio Commission in 1927 of
frequency standards for broadcasting stations, the Bureau was made re-
sponsible for their testing. New allocation of broadcasting channels and
station restrictions imposed by the Commission, as well as the improved
instruments, equipment, and filtering devices that had become available,
ameliorated the problem of station interference for the time being. The
Dellinger, "The status of frequency standardization," Proc. IRE, 16, 579 (1928).
That certainty, to within 1 part in 100,000, was exceeded in 1930 when the Bureau devised
a primary frequency standard with an error of 1 part in several million (NBS Annual
Report 1930, p. 22; RP759, 1935). By 1960, with frequency standards based on
atomic radiation beams, reliability was in the range of parts in 10 billion. (Dellinger,
MS," Fifty years of radio in the NBS," 3 March 1961, p. 6, NBS Historical File.)