Sound Mirror (Redcar, Royal Engineers, 1916)

All photos by Stuart Redpath

As the threat of German zeppelins loomed (literally) over the county during World War I, Britain erected an extensive system of defence and detection on the vulnerable East Coast. A part of this system were the early warning stations, otherwise known as parabolic acoustic mirrors or sound mirrors.

This one in Redcar dates from 1916, and stands in a housing estate just inland of the town’s Rugby Union Club. It was built by the Royal Engineers and is a scheduled monument.

All photos by Stuart Redpath

The plaque in front of the Sound Mirror (which was campaigned for by local historian Vera Robinson) explains how it works:

“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.”

Although many of these structures were torn down, many more have survived on and near headlands and beaches along the coast.

Here you can listen to an excerpt from World War One At Home, which explains the mirror’s post-war life as a “farmer’s dung dump”.

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