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

354 THE TIME OF THE GREAT DEPRESSION (1931-40)
The radiosonde, developed
for the Navy by the Bu-
reau in 1936, telemeters
information on upper air
pressure, temperature, and
humidity from unmanned
balloons. It employs an
ultra-high-frequency oscil.
lator and a modulator.
The frequency of the lat-
ter is controlled by spe-
cial resistors whose electri-
cal resistance varies with
the atmospheric phenom-
ena. At the receiving
station on the ground or
on shipboard, a graphic
frequency recorder, con-
nected in the receiving set
output, provides an auto-
matic chart of the varia-
tions of the phenomena
with altitude.
Subsequent refinements in the radiosonde included improved instru-
ments such as the electric hygrometer,161 superior electronic components,
and more recently, miniaturization. These were also used in the special radio-
sonde designed for the Navy to operate as an automatic weather station.
Instatied on isolated islands or in mountainous regions, the radiosonde
transmitted data on temperature, pressure, humidity, wind velocity and direc-
tion, and rainfall via keyed frequencies picked up and recorded at the nearest
Navy base.162
The international interest in telemeteorography that led to the radio-
sonde coincided with a new age of exploration—ionospheric, stratospheric,
and terrestrial—marked early in the decade by the Second International
Polar Year of 1932—34. Available to that Year were the airplane, radio, and
a range of scientific instruments and equipment denied the First Polar Year,
held 50 years earlier, in 1882—83. In that initial cooperative assault of
science on the icy unknown, meteorologists and astronomers of 11 nations
had acted in concert to explore the polar regions and, from 12 bases around
the Arctic and in the southern ocean, make observations of polar weather,
RP1329, 'An improved radio sonde and its performance" (Diamond, Hinman, et al.,
1940); Science, 90, 246 (1939).
Mass production of the radiosonde was turned over to several companies in 1937, includ-
ing Bendix-Friez of Towson, Md. In the next 26 years, Bendix alone manufactured
more than 2 million units. "Baltimore Evening Sun," Sept. 6, 1963, p. B6.
RP11O2, "An electric hygrometer * * a" (Dunmore, 1938), and its improvement,
RP1265 (1939).
RP1318, "An automatic weather station" (Diamond and unman, 1940).