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

NUCLEAR PHYSICS AND RADIO PROPAGATiON
cies, and standard musical pitch (middle A at 440 cycles per second), which
the Bureau radio station, WWV, had broadcast since 1935.127 As supple-
mentary to the time signals of the Naval Observatory, the signals are widely
used by such industries as mining, shipping, railroads, power, air transport,
and communications, among many others.'28
Within a year after beginning its new time signal service, improved
standards resulted in achieving a maximum change of 0.001 second per 24
hours and deviations of as little as 0.009 to a maximum of 0.031 second
from corrected Naval Observatory time.129 Extending reception of the
frequency and time signals of WWV, on November 22, 1948, the Bureau
established a new experimental broadcast station, WWVH, on the island of
Maui in Hawaii. Soon after it began operations, reports confirmed the
expected success of the station in reaching with consistency a far greater
range of areas in the Arctic and the Pacific than had been possible from
Maryland.13°
CRPL's extension of the primary frequency standard to 40,000 mega-
cycles in 1948 helped to open research in a field of physical science first
explored during the war, that of microwave spectroseopy. Of immediate
importance to the Bureau work on guided missiles, the new methods devised
for measuring electrical quantities at microwave frequencies made possible
the use of sharp microwave beams on systems where high resolution was
needed, as in short-range target-seeking rockets and missiles.'3'
'2TNBS Annual Report 1946, p. 206; NBS TNB 31, 21 (1947); Radio News, 38, 118
(1947).
Long concerned with time as a factor in all measurement, and with clocks, watches,
and sundials (on which it issued many Letter Circulars), the Bureau began testing time-
pieces shortly after its founding. See C51 (1914) and the current C432 (1941) on the
testing of. timepieces.
The propagation of standard time signals has been by tradition the prerogative of the
Naval Observatory at Washington. The Bureau has also had an interest in standard
timekeeping, dating back to World War I. Under an act of March 19, 1918, authorizing
the establishment of daylight saving time and standard time zones in the United States,
Congress appointed the Interstate Commerce Commission to define the limits of each time
zone for the Nation. As a matter involving "standards," the ICC requested the Bureau
to prepare the map from data that ICC supplied. The map was first published in 1925,
in an NBS circular on standard times throughout the world (C280, currently C496, 1950),
and a "standard time conversion chart" appeared in 1928 (M84). In 1930, over objec-
tions from the Department of Commerce that such a map was no function of the depart-
ment, the Bureau replied that it was part of its information service to the Nation's
commerce. It appeared in a separate publication that year as Mill, currently M190,
1948. See Department of Commerce correspondence of August—September 1930 in
NARG 40, Box 120, 67009/93.
120 NBS Annual Report 1947, p. 223.
"°NBS Annual Report 1949, p. 81.
130 NBS Annual Report 1948, p. xiv.
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