Sonic locating device of the American air defense, 1931
At the same time as the introduction of the giant French sound receiver, the American army also brought into service a device which can receive engine noise from aircraft at long distances and which can determine the direction of the noise source
Picture No
10633132
Media ID
48203327
Size
2283px x 1715px
(1.4MB)
Credit
Mary Evans / Sueddeutsche Zeitung Photo
Usage Restrictions
No model release, no property release. No commercial, merchandising or advertising use without prior permission from Mary Evans Picture Library
