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   Undertoad  Monday Jun 21 10:25 AM

6/21/2004: Sound mirrors

I'd never seen these things before Agenda Bender pointed them out via Apothecary Drawer.

They sit in the south of Britain, these on the coast of Kent. They are massive: the biggest dish there is 30' high, and the big wall is 200' long. They are sound mirrors, made of concrete. They were built in the 1920s. The intention was to listen to what they reflected, using microphones or even stethoscopes, to hear the engines of incoming enemy aircraft.

By the mid-30s someone figured out that RADAR was much better for this purpose, and suddenly the sound mirrors were useless. They fell into disrepair and now there are only a few of them left. This is the biggest set of them, and they are now considered historic and will be preserved.

You can see how large they are by the graffiti.

more photos and explanation

scientific/archaeological discussion

big pictures

Beestie  Monday Jun 21 10:39 AM

xoxoxoBruce  Monday Jun 21 11:18 AM

Great find, UT. I can imagine a guy sitting there listening to a stethoscope, when a flock of seagulls comes by.

hot_pastrami  Monday Jun 21 01:04 PM

There's some real ingenuity at work, there. These buggers were not only able to detect the approach of motorized aircraft as far as 15-20 miles away, but also the direction, when a trained ear was involved. Nifty. I'm glad they're preserving a few.

ladysycamore  Monday Jun 21 01:38 PM

all I can say is awesome.

mmmBoy  Monday Jun 21 03:03 PM

This was, of course, just the allies response to Hitler's dreaded "Das CheericerälÜberWeapon."

Torrere  Monday Jun 21 03:13 PM

A few thousand years later, the inhabitants of Britian wonder what the hell these giant stone dishes were made for, or who made them. One person decides that they were meant to collect rain during a drought, another decides that they were built for a spiritual purpose by a culture of moon-worshippers. (Actually, I think that a reasonably bright person and educated person would be able to figure out what they were supposed to do fairly quickly, although they might be stumped for 'why').

Damn cool artifacts. I hope that they last a long time.

lumberjim  Monday Jun 21 04:26 PM

a few thousand years later, the kids will be using their 0 gravity skateboards to shred that bowl, and won't even wonder about who made them.

GuyNamedGuy  Monday Jun 21 06:56 PM

I've ben lurking and gawking at the images for a few months and finally decided to throw my two cents in (and that's what many of my thoughts are worth)

1. Is there any data on how well these things worked? I'd seen pictures of smaller types used by sailors and some things used in WW1, but nothing on so heroic a scale. I imagine standing at the focus of these things must be very strange, like being at the "sweet spot" under a dome.

2. Is it just me, or does anyone else want to explode an m-80 at the focus of one of those things?? It'd be like a sound cannon - I wonder how far off it could be heard.....

Or, instead of an m-80, a shaped charge to throw all the oompth towards the wall.......

hot_pastrami  Monday Jun 21 06:58 PM

Originally posted by GuyNamedGuy
Is there any data on how well these things worked?
According to the linked article, the max distance a motorized aircraft could be heard was about 20 miles. It detected a real raid about 10-15 miles out on one occasion. Not too shabby for a giant concrete cereal bowl.

mmmBoy  Monday Jun 21 08:03 PM

Originally posted by GuyNamedGuy
Is there any data on how well these things worked?

My wife just finished a Ken Follet novel last week called "Hornet's Flight" that was based on these crazy things. I guess that there was one large one in the middle and two smaller ones on either end, and it worked surprisingly well.

My only question is, if you were listening during a thunderstorm, wouldn't you go completely deaf?

Thanks for posting these, really cool.

xoxoxoBruce  Monday Jun 21 08:18 PM

Or, instead of an m-80, a shaped charge to throw all the oompth towards the wall.......
Welcome to the Cellar, Guy You could probably knock the seagulls out of the air with that charge.

GuyNamedGuy  Tuesday Jun 22 12:44 AM

15 to 20 miles is pretty darned good for something with no moving parts. It would have worked pretty well against the WW1 Gotha bombers moving at around 100 mph under 10,000 feet, but would never give enough warning against modern WW2 bombers or even the slower Stukas. And this 200-foot concrete wall - obviously you can't re-point or aim the thing to check different approaches, although the mechanism to swing it around would have been impressive!

Would slaughtering seagulls at the shore be the same as poisoning pigeons in the park?

And if there is one avian species I'm less worried about going extinct than seagulls, it's hard to name - to quote a friend of mine, "Kill all you want - we'll make more".

Thanks for the welcome, glad to be aboard!

Archer  Tuesday Jun 22 01:38 AM

We used to have something like this at the Childrens museum in Indy. The discs were probably on 7 feet tall, and about 50-70 apart. *But* if you were standing in front of the "mic" (which was also the focus point for the parabola you could litterally hear a whisper made from the same spot accross the room. A room filled with screaming children no less.

I never gave it much thought, though I've always rememdered those things. It was just so amazing that you could hear someone whisper something.

edit: I still spell like a three year old

youblues  Tuesday Jun 22 02:49 PM

These sound mirrors are featured in a film art work by Barry Hale called: "Blackout The Antiphony Video Supplement." They were also featured on the cover of Disinformation's "Antiphonny" music cds (1997). The film can currently be seen as part of "The Origin of Painting" exhibition by disinformation, which is currently at Q Gallery, Derby, U.K.

xoxoxoBruce  Tuesday Jun 22 06:45 PM

Hey, welcome to the Cellar, youblues. Did you know all that or have to look it up?

richlevy  Tuesday Jun 22 10:23 PM

I was thinking that if you lined them with aluminum foil you could make a nice solar oven, except for the fact that they are probably facing west and are located in England.

xoxoxoBruce  Wednesday Jun 23 05:40 PM

Facing east, over the channel.

xoxoxoBruce  Thursday Oct 7 07:47 PM

I think this may be one of the same thing. He appears to be on a beach and the same time frame.

mmmBoy  Thursday Oct 7 08:01 PM

Wow, a portable model. How convenient! It kind of looks like the arms telescope out? It could also be some 1920's robotic Jai Alai game...

Nice find, that's hysterical.

footfootfoot  Thursday Oct 7 10:03 PM

Originally Posted by lumberjim
a few thousand years later, the kids will be using their 0 gravity skateboards to shred that bowl, and won't even wonder about who made them.
That is, until Elspodes's descendants create a religion around them.

And what a cool religion that would be...

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