The acoustic sound mirror at Kilnsea, Hoilderness, East Yorkshire, England UK
The acoustic mirror at Kilnsea in the East Riding of Yorkshire is one of a number built on the northeast coast of England during the First World War. A forerunner of radar, they were intended to provide early warning of incoming enemy aeroplanes and airships about to attack east coast towns. The mirror is made of concrete, with a dish about 15 feet in diameter in the side facing the sea. It worked by focusing the noise of aircraft engines onto a microphone, which amplified the sound. In this way the relatively slow aircraft of the time could be heard and located before they came into view. The microphone would have been fitted to the metal post set in a concrete block in front of the mirror. An operator would use headphones to listen for an approaching enemy. With the development of faster aircraft the sound mirrors became less useful, as an aircraft would be within sight by the time it had been located.
Size: 5344px × 3625px
Photo credit: © John Morrison / Alamy / Afripics
License: Licensed
Model Released: No
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