At 10:51 AM 11/7/2010  -0500, Paul Guzyk wrote:
>It will come out without breaking, honest.

Every trade has tricks they play on the fresh-caught.  On the
electronics repair line we used to randomly twist all the knobs on
the guy's oscilloscope and watch to see how long it took him to get
it set up again.  A body-shop guy told me a favorite trick on the new
guy was to set up an old rear window on a couple of blocks and tell
him to jump on it and break it.  After he got tired of that they'd
get a little punch and a light hammer and tap the corner with it...

I've always wondered if Prince Rupert was testing a theory or just
had an accident when he dropped molten glass into cold water...glass
is actually very strong in tension, but it's cursed by the fact that
it's insanely prone to surface cracking, and since the stress at the
bottom of an extremely fine crack is essentially infinite the tensile
strength doesn't help much.  Tempered glass uses either chemical or
thermal methods to put the extreme outside skin of the glass into
strong compression, so all the cracks are squeezed tight shut.  Of
course if you break that skin the whole piece flies apart.  I was
playing with a piece of storm-door glass one day trying to see if I
could get away with something -- well, I couldn't.  Probably half the
glass ended up around the edges of a 12x24 foot shop...

Yours,
David