"AZIMUTH AND ELEVATION SETS HORN-TYPE SOUND detectors at the end of the base line in Ellington Field, Houston, Texas. This photograph was taken in December 1918. The purpose of these sound detectors was to track and locate possible enemy aircraft or incoming threats. "

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Size: 8425px × 5741px
Photo credit: © piemags/NSC / Alamy / Afripics
License: Licensed
Model Released: No

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