From: Paul Burke
Subject: Re: O.T. Math help
Date: Mon, 11 Nov 2002 08:53:11 +0000
Organization: Scazon Systems
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Michael Painter wrote:
> It just occurred to me that nobody every talks about the material
> at the top of the glass being thinner or the ripples in the glass changing.
> You may be right about putting the thick side down, but I wonder if some or
> all the edges might be thick?
They used three basic techniques for making glass window panes in the
17th century. One way, you had a big vat of molten glass, and dipped the
bottom edge of a frame into it. The glass stuck to it, and you drew the
frame upwards, resulting in a sheet of semi- molten glass dangling from
it. This would flow until it set, so you got a pane thin at the top,
thick at the bottom, and full of ripples, bubbles etc.
The second way was to dip a stick in, get a blob of glass, and rotate it
rapidly, using centrifugal force to make a circular sheet. This was then
cut up. The attachment of the sheet to the stick had a point in the
middle, and being misshapen was cheaper- this was the "bullseye" so
beloved of Christmas card artists.
The third way, you blew a cylinder like a big bottle, then slit it along
the length and straightened it out. This resulted in much finer, more
consistent glass, but still rippled.