Friday - September 23, 2011

All That Is Old Is New Again

I have Doc Jeff to thank in part for this one. Thanks for the link Doc!
Ever since TinEye and Google Image Search came on the scene, it’s been pretty much impossible to do a WhatsIt. No matter what picture I put up, unless it’s one I photograph myself, you can find it in a second. Grrr.  But if you’d like to play along and can resist the temptation to use an image search tool, here’s a really neat thing.

It’s a hexagon pyramid of glass that measures about 4” across. This one is green, but most of them were clear. The pyramid could have 4, 6, 8, or more sides, but 6 was fairly common. Some of them were as small as 2” across, but almost none of them was larger than 6” across because that would make the pyramid too tall.

As a very small child, I stood on several of these without injury. Heck, I probably jumped up and down on them, since I was that kind of boy.

These have been around ever since mankind had the ability to make fairly clear glass and understood it’s properties. Some of the later ones are not pyramids at all but fluted, which utilizes the same property but in a different way. Some of them also had a rim around the edge, but most didn’t. Wiki thinks they’ve only been around since the 1840s, but Wiki is wrong about lots of things. I think they might date back almost to Roman times.

Have at it. And then check below the fold for the answer, and for Doc’s link to a modern zero-cost implementation that is about as “green” a solution to an age old problem as can be found.

They are called deck prisms. They were mounted flat end up in the planks of a wooden sailing ship’s deck, and allowed light to shine below decks without the danger of candles or oil lamps. Generally there were held in place with tar, or a bit of oakum, which is the ropey tarry stuff sailors used to stuff the cracks between the boards of their boats so that the ocean stayed on the outside.

Here’s a link, with lots of pictures of real ones, to the ones I stood on as a 4 year old boy. They still work just fine, more than 170 years later. (from when they were made, NOT from when I was born!!) And the gift shop at the link sells them, in case you’d want your own for a paperweight, curio, or palm mace. Hey, you never know.

So why is “all that was old is new again”? That brings us to Doc’s link. Seems there this guy in the Philippines who is installing them on the tin roofed slums there. His aren’t made from glass, they’re made from old 2 liter soda bottles filled with water and perhaps a bit of bleach. The refractive properties of the water in the clear plastic bottle work just like the prismatic property of glass, and this brings quite a bit of light into this dark windowless dwellings. And it costs nearly nothing; the soda bottles are picked from the trash heap. So it’s light without electricity and recycling both at the same time.

Watch the video too. Neat.

Fiat lux!

Oh, and my guess is that the fluted ones used the Fresnel lens principal to radiate light, or something closely related to it. Whether they work better than the pointy ones is beyond my knowing.

GET ME OUT OF HERE ...

Posted by Drew458     on 09/23/2011 at 11:44 AM   
Filed Under: • Fun-Stuff • History • Science-Technology •  
• Comments (6) • Trackbacks(0)  Permalink •  

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