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The U.S. Weather Bureau, which transferred this radiosonde to the Smithsonian, described it as an experimental model for high altitude weather observations, made ca. 1942. A label on the pressed paper container reads "SIMMONDS CHRONOMETRIC RADIOSONDE... SIMMONDS AEROCESSARIES, INC., NEW YORK” and “P.B. I21." Inside is a blocking oscillator, an FM transmitter, and a clock-driven switch. Sensors for measuring temperature (bimetallic), pressure (aneroid), and humidity (hair hydrometer) are attached. Simmonds Aeroccessories, Inc. may have been a British firm with an American office.
Ref: “New Weather Aid Now Perfected,” American Aviation 6 (1942): 35.
Currently not on view
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overall: 11 in x 7 in x 6 5/8 in; 27.94 cm x 17.78 cm x 16.8275 cm
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Medicine and Science: Physical Sciences
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National Museum of American History
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