Interesting bit of history that I never knew existed


https://www.bbc.com/news/in-pictures-46348917

More than 100 years ago acoustic mirrors along the coast of England were used to detect the sound of approaching German zeppelins.

The concave concrete structures were designed to pick up sound waves from enemy aircraft, making it possible to predict their flight trajectory, giving enough time for ground forces to be alerted to defend the towns and cities of Britain.

Invented by Maj William Sansome Tucker and known as sound mirrors, their development continued until the mid-1930s, when radar made them obsolete.

Joe Pettet-Smith set out to photograph all the remaining structures following a conversation with his father, who told him about these large concrete structures dotted along the coastline between Brighton and Dover.

It's something I've always meant to go and see/hear especially the ones at Romney Marsh

https://theromneymarsh.net/soundmirrors

Thanks, that was an interesting read - both of those links.

Another interesting bit of UK history that I was unaware of. That and the Anderson shelters.

So that concave monument was not built by the Romans?

And heres a Tom Scott video on the same subject.

I've experienced "that" in the form of a pair of parabolas about fifty feet apart inside a huge and noisy science museum decades ago.

They were maybe 2/3 the diameter of the cement one pictured above, facing each other perfectly, and there was a metal ring a few inches in diameter at the center of each one where you'd speak into. A person standing at the other parabola could hear your voice as if you were right next to their ear (and vice versa) despite all the noise of the crowd. Pretty strange experience.