Hi Roger, Brad,
I was just supposing that it was 9 hours before sunset, and guessing that I'd
have to add 6 hours to the 3 shown. I AM interested in "hours before
sunset" whatever one might call them locally. For instance, at exactly 45
degrees north latitude, when a vertical pole's shadow is pointing exactly
west, it is 12 hours til sunset.
Brad, Is it possible in your "soda can" model to have the hours before
sunset actually calculated from true sunset, which does vary considerably at
higher northern latitudes. I'd also be interested in being able to use a
different size can, especially a taller one so that nearer the equator,
summertime hours would all fit on the display. The soda can idea is
certainly a great one, and the use of the gnomon that doesn't stick out to the
side is also a neat idea. Hmmm, Chris Taylor's idea of duplicating the
scales, showing AM hours on one set, PM hours on a separate set which
would allow one color printing as well as reduce the clutter in winter months,
sounds neat too! Yes, I'd like to try your java version as I run a number of
operating systems.
Thanks much!
Edley McKnight
From: "Roger Bailey" <[EMAIL PROTECTED]>
To: "Edley McKnight" <[EMAIL PROTECTED]>,
"Lufkin, Brad MMission Systems\""
<[EMAIL PROTECTED]>,
"Sundial Mailing List" <sundial@uni-koeln.de>
Subject: RE: Portable Dial Adjusted for EOT and DST
Date sent: Thu, 26 Oct 2006 09:47:43 -0700
-----Original Message-----
<On the Babylonian and Italian hours you add 6 if necessary?
<Edley McKnight
Hello Edley,
Italian and Babylonian hours are 6 hours from local time only on the
equinox. Italian hours start at sunset; Babylonian hours start at
sunrise.
Both involve 24 equal hours per day. Since sunrise and sunset times
vary
through the year, the difference from local time varies as well. See
my
"Timelines.ppt" presentation, a 16.5 MB file at
http://www3.telus.net/public/ormerod/NASSVanRTB/
On Brad's "sodaCan.png", I only see the blue lines for Babylonian
hours,
with black AM and red PM civil times and no Italian hours. It is
interesting how these Babylonian hour lines are fairly flat through
much of
the year and much of the day, diverging most around the summer
solstice and
noon. Not surprising when you think about it, the altitude of the sun
being
fairly constant at a given time after sunrise. This is the benefit
of
concepts like this. They get you to "think about it". Thanks Brad, for
the
challenge.
Roger Bailey
Walking Shadow Designs
N 48.7 W 123.4
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