More polarized fun...

A much more easily viewed demonstration of the effect we are discussing here is 
looking at clear glass table tops outside. If you happen to have some lawn 
furniture that includes a clear tempered glass table top, all you have to do is 
stand to the east or west of of the glass and look down at it at an angle of 
approximately 56 degrees and you will see beautiful pools of color. The colors 
outline the birefringence caused by the strains in the tempered glass.

Once in a while a random observation at my back yard of the phenomenon by a 
friend or family member will be alarmed at "something wrong with the glass". 
And of course, their eyes glaze over when I try to explain it.

You might wonder why I immediately recognized Harry's noticing of mysterious 
color effects during his walk. It's simple. When I was very young, I used to 
see these colors in the pavement all the time, directly on, not peripherily. 
The reason is my brother and I were blessed, or cursed, with vision that was so 
sharp and light sensitive that we were accused all the time of "seeing things". 
We tested out at 20-05 on the eye charts. Our retinas must have been so stuffed 
withe rods and cones, I'm surprised they didn't explode. I could see close to 
7th magnitude stars. That's all gone now that I'm old. Down to 20-20 with lens 

Please pardon my self-indulgent nostalgia.



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