Hi All,
I printed out a horizontal dial for my 87 year old father. I make
it with Zonwvlak (available from NASS). After reading the directions,
I found the software powerful yet easy to use. F.J. de Vries did an
excellent job in writng the software. I found that Ami Pro 3.0 will
import a picture in the .plt format under HPGL as the choice format.
The aspect ratio is maintaind and it prints to a full sheet of paper.
I had a minor problem using the draw program (Scrplt) because I could
not always remember the file name that I had created.
Now for a few general questions.
Babylonian hours. I take it these are the lines for each hour
since sunrise. I also assume they are each 1/24 of a day long.
Are they numbered from sunrise, with sunrise=0, one hour later as 1
two hours since sunrise as 2 etc?
Italian hours. I understand these to be the hours until sunset.
I would take these to also be 1/24 of a day in length. Is sunset=0
and one hour before sunset=1, etc?
What exactly is a bifilair sundial? I take it that it has two planes
perpendicular to each other. If so why does Zonwvlak only print one
surface? No wait....reading.....does a bifilair dial use the lines on
a transparent surface to be read with one point where the "shadows" hit?
Now for a math question. In analytical geometry the equation of an
ellipse is: (with the origin at the center and semi-axes a and b)
(X**2/a**2) + (y**2/b**2) = 1 (**2 means squared)
the equation of a hyperbola is:
(X**2/a**2) - (y**2/b**2) = 1
Can we draw a sundial from these equations? How are a and b related to
latitude, declination of the sun, and hour angle? This will keep me off
the streets and out of trouble for a while.
Sincerely,
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Warren Thom [EMAIL PROTECTED] or [EMAIL PROTECTED]
Hompage Still working on it.
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