6/21/2004: Sound mirrors
 

http://cellar.org/2004/soundmirrors.jpg

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.

http://cellar.org/2004/soundmirror2.jpg

You can see how large they are by the graffiti.

more photos and explanation

scientific/archaeological discussion

big pictures

http://members.cox.net/xycof/sndmr.jpg

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

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.

all I can say is awesome. :)

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

http://www.rpm33.com/misc/hitlerCereal.jpg

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.

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.

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) :D

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.......:thumb:

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.

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

Welcome to the Cellar, Guy :) You could probably knock the seagulls out of the air with that charge.:haha:

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! :rolleyes:

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!

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

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.:rolleyes: