Bob Haselby <[EMAIL PROTECTED]> wrote: > Tony, This sounds like a "signal mirror" which were also contained > in life jackets etc as survival gear. The more modern are quite > effective and are great for annoying people on the beach. It uses > double internal reflection in the hole to give a virtual image of > the sun and so it is easy to hit what you are aiming at even though > you are to far away to see the actual reflection on the opject that > you are trying to hit.
> Bob > San Diego I believe "double internal reflection" must be the explanation I was looking for. I'll have to give it some thought. I also remembered another detail after I sent my last message; the annulus had a colored portion, and I believe it was the colored portion that lent the color to the indicator spot which I described (it's been thirty years since I last saw this item... it's hard to recall all the details). I wish I knew where to buy one of these gems so I could experiment... On occasion I've looked in recreational equipment stores to no avail. Jim ------------------- ---------------------- -------------------- | Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] | | Parametric | Salt Lake City, UT | (801)-588-4632 | | Technology Corp. | 84108-1202 | Fax (801)-588-4650 | ------------------- ---------------------- -------------------- It's a good thing that we don't get all the government we pay for.
