Cousin Ricky <ric### [at] yahoocom> wrote:

> Contrary to what you may have heard, glass does not flow;

I'm inclined to argue from observation (anecdotal evidence) that it does.  vide
infra *

> if it did,
> large telescopes would fall permanently out of focus.

But there are many types of glass, and some may flow orders of magnitude slower
than others.

> The reason some
> medieval windows are thicker at the bottom is that glass making
> technology was not as precise in those days, and the builders who
> installed the subsequently uneven panes were not stupid.

Interesting, but not in and of itself proof that glass does not flow.

* I have driven past old industrial buildings in, IIRC, northern New Jersey
(probably ironbound Newark) and the glass panes in the windows had flowed down
so much that there were holes opened up and the glass all collected and bunched
up at the bottom of the hole.

Now unless there were some amazing heat (I saw no evidence of fire damage - no
soot marks, frames still intact) I don't see how that would have happened unless
glass does indeed flow.

It would be interesting to put a weight on a pane of flint glass supported on
either end by sawhorses, and see what happened over a long period of time.

-BW

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