MIRRORS

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Stanley
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MIRRORS

Post by Stanley » 03 Nov 2017, 07:41

MIRRORS

'Mirror, mirror, on the wall. Who is the fairest of them all?' I'll bet everyone remembers that rhyme! The question is, how can you tell from looking in a mirror? The image you see is a reversed version and not a true likeness. How many of you learned 'The Lady of Shallot' and remember that she was forbidden to look directly out of the window but only via the reflection in her mirror. Then there is 'Alice through the Looking Glass'. There is something about mirrors that has an enduring fascination, after all, breaking one gives us seven years bad luck! Everyone knows that the way to identify a vampire is by looking at them in a mirror, vampires don't have a reflection...
I suppose our earliest ancestors first saw their reflection in still water and puzzled over what the image was. It wouldn't take them long to realise that there was something strange going on as the scar was in the wrong place. How could this be? Further, our faces aren't symmetrical. Have you ever seen a picture of yourself where the image is divided by a centre line and each side reversed and put with its double to produce an image. The two images of a double left and a double right are surprisingly different.
In sunny climes mirrors have been used in warfare. The Greeks tried using large mirrors to blind the steersman of invading ships of war. The heliograph was a clever invention used extensively by the Indian Army as a way of communicating over a distance using Morse Code and a mirror reflecting sunlight that could be accurately aimed at a distant observer.
Convex mirrors are used at blind junctions to give sight of oncoming traffic and in shops to enable staff to keep an eye on customers in the fight to contain shoplifting. The climatologists tell us that the biggest mirror in the world is Polar Ice and the fact that it reflects sunlight back into space makes it a vital component in combating global warming. If it is darkened by ash fall out from a volcano there is a measurable rise in temperature. In deserts, arrays of mirrors all focussed on one point have been used to produce pure heat for scientific experiments or to heat a boiler producing steam to drive turbines and produce carbon-free electricity. There is more to mirrors than meets the eye and we have come a long way from Narcissus being obsessed by his reflection in water or the early civilisations using polished plates of metal to gain a reflection.
I suppose all the above reflects the fact that I should get out more! But I can't help being fascinated by mirrors. I remember that a full length mirror on the guard room wall at the entrance to the barracks was standard equipment when I was in the army and we were required to check our appearance before going out into the wide world. I still do that.

Image

The mirror at Bancroft used for checking smoke from the boiler house.
Stanley Challenger Graham
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"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!

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Tizer
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Re: MIRRORS

Post by Tizer » 03 Nov 2017, 09:50

Gardeners and model railway enthusiasts make good use of mirrors to trick the brain into thinking it's seeing a more distant image. The gardener will make an arch and put a mirror behind so it looks like there's another garden beyond. The railway modeller will put a bridge at the end of the layout with a mirror behind and this gives the impression of much more railway world beyond. Periscopes are another good use of mirrors although I expect the ones on submarines are replaced by digital equivalents now. Most people know about mercury being used on glass to make mirrors but less well known is the liquid mercury mirror telescope: LINK

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Stanley
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Re: MIRRORS

Post by Stanley » 04 Nov 2017, 04:23

Interesting. I knew the effect but not the use. I was always impressed by the fact that the large prismatic light units in lighthouses floated on mercury as a low friction, maintenance free bearing.
Stanley Challenger Graham
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scg1936 at talktalk.net

"Beware of certitude" (Jimmy Reid)
The floggings will continue until morale improves!

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