World War, 1914-1918--Technology--Airplanes
Article title "Aerial defenses of Paris"
Caption "This Detector, which consists of four megaphones connected with a microphone and equipped with receivers is used day and night: with it the purr of an aerial engine may be heard while the machine itself is invisible"
Cover image title "Electric ears detect invading air craft"
Popular Mechanics Magazine, v. XXV, n. 1, 1916, cover and p. 34
Still Image Item Type Metadata
“Electric ears,” War of Wonders, accessed 23 gennaio 2019, http://warofwonders.com/items/show/115.
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