Post by wearwolf on Aug 12, 2015 20:28:34 GMT
An unusual relic of World War I, the Fulwell Acoustic Mirror, on the outskirts of Sunderland, has recently had a bit of a makeover.
A 4m high concave concrete dish, constructed in 1917, it was designed to act as an acoustic early warning system against air raids, after a bomb dropped by a Zeppelin over the Wheatsheaf area of Sunderland in April 1916 left 22 people dead and more than 100 injured.
The mirror worked by reflecting sound detected by a microphone in front of the dish to an operator with headphones who raise the alarm about approaching Zeppelins.... although operators apparently sometimes found it difficult to distinguish between aircraft and seagoing vessels.
Operators usually sat in a trench in front of the mirror, but apparently an archaeological survey conducted at the same time as the make-over found no traces of one in this case. They may just have been obliterated over the years, or perhaps a different system was used here.
Apparently it could give around 15 minutes warning of approaching airships.
More photos at : spiritofplace.weebly.com/fulwell-acoustic-mirror.html
more on acoustic mirrors at : www.andrewgrantham.co.uk/soundmirrors/
