re:flat glass

Dave K wrote:

>something like 10 million years for a window
>pane to get 5% thicker on the bottom at "normal" temps.

Guess someone should tell the restorers of old houses! I've taken
windows out of houses less than 100 years old, where the glass is at
least twice as thick at the bottom (compared to the top)!

Hope this helps.

Ballendo