In message , News
writes
In message , Rod Speed
writes
"News" wrote in message
...

Our windows are all still original Victorian sash, and many panes
(with flaws) are probably original, too. One bedroom window, at the
front, is odd. Traditional sash, with four panes of glass, yet one
of the four always looks as though it is not there, from outside. It
just looks dark, and you would think the whole pane was missing.
Looking out, from the bedroom, it looks exactly like the other three. No idea why.

Presumably the outer surface is different because
it got broken and replaced at some time.

Indeed, but why? Other panes have been replaced over time, and look
the same from both inside and outside. Why just that one? Rhetorical
question, really. Strange, though.

Broken and replaced with Pilkington K. ?

--
Tim Lamb