Acoustic mirrors like this were built along the east coast of England to listen for the engines of approaching enemy aircraft. When in use, there would have been a post with a listening device positioned in front of the parabolic surface.
Although the mirror is now in a built up area, during World War I, this was open fields and there would have been interrupted views out to sea.
The accompanying plaque reads:
REDCAR EARLY WARNING STATION
This structure is a Sound Mirror or detector, built by the Royal Engineers in 1916. It was part of an extensive Zeppelin and enemy aircraft detection system deployed down the East Coast of Britain druring the First World War. Zeppelins raided the North East Coast 15 times between April 1915 and November 1917.
The sound of approaching aircraft was reflected off the concave ‘mirror’ surface and received into a trumpet mounted on a steel column.
The trumpet was connected to a stethoscope used by the operator or ‘listener’, and the part of the dish that produced the most sound indicated the direction of the approaching aircraft. Advanced warning of an imminent attack could then be given to local people.
By the early 1940’s sound detection technology was being replaced by ‘reflective detection finding’ now known as radar.
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