An “Aircraft Listener” photographed in the 1920s using a device with scoop-shaped reflectors which direct the sound into large-diameter tubes in order to try and locate aircraft at a distance from the sound of their loud engines before the advent of radar

An “Aircraft Listener” photographed in the 1920s using a device with scoop-shaped reflectors which direct the sound into large-diameter tubes in order to try and locate aircraft at a distance from the sound of their loud engines before the advent of radar

by Front-Coconut-8196