Keith,
The formula from Waugh should work fine but only for a dial with the gnomon
aligned to the rotation axis of the earth ie pointing approximately to the
pole star. I do not think that you can use a horizontal gnomon with a
vertical dial to record the passage of modern hours. However, you mig
Note that the hour markings will be reversed about solar noon. In the northern
hemisphere the shadow moves anticlockwise on a vertical surface.
John Lynes
--- On Wed, 10/9/08, The Thurstons <[EMAIL PROTECTED]> wrote:
> From: The Thurstons <[EMAIL PROTECTED]>
> Subject: RE: V
If you create another horizontal gnomon on a digfferent distance of
the sundial face you have bifilair sundial. It reads the time/date
from the crossing of the 2 shadows.
Thibaud Chabot
At 06:03 10-09-2008, Keith E. Brandt, WD9GET wrote:
Sunny friends,
For various reasons, I'm wanting to buil
Keith,
What you want is quite simple, once you grab the idea. Imagine a
classical vertical dial, including its pole-style. Take one point
somewhere on this style, and remove the style except this point. How to
prevent it from falling down? Yes, put it on top of a supporting rod. In
your case,
>The formula from Waugh should work fine but only for a dial with the gnomon
> aligned to the rotation axis of the earth ie pointing approximately to the
> pole star. I do not think that you can use a horizontal gnomon with a
> vertical dial to record the passage of modern hours...
---
Dear Keith,
Ah, that's not quite what most replies assumed! Yes, you certainly can
calculate straight hourlines radiating out from the foot of an
arbitrary-length horizontal gnomon for a particular date.
Here's how I would solve it:
As you may know or can probably visualise, a south-facing vertica
Hello Keith,
You posed a interesting question and have been getting good advice.
1. To show regular hours throughout the year, you need a polar gnomon.
2. Any point on that polar gnomon, the end or a node, traces the hour lines
of interest
3. The shadow path of that point can be calculated
Dear Keith,
If you can accept a horizontal gnomon that is _almost_ horizonal,
then my vote would be for a vertical Foster-Lambert dial. At latitude
30, the gnomon would be at 75 degrees. It could be of arbitrary
length. And the dial itself is a 'doddle' (pardon for the
Australianism) sinc
Cc: <[EMAIL PROTECTED]>
Sent: Friday, September 12, 2008 4:25 AM
Subject: Re: Vertical South dial with horizontal gnomon
> Dear Keith,
> If you can accept a horizontal gnomon that is _almost_ horizonal,
> then my vote would be for a vertical Foster-Lambert dial. At latitude
>
I'm getting much much closer on my date-specific south-facing vertical
dial thanks to the help I've received from several on the list (and no
thanks to Hurricane Ike which provided a couple of weeks of cloudy skies
and distraction from dialing!)
I'm down to solving what is probably a simple three
TED]>
To: "sundial" <[EMAIL PROTECTED]>
Sent: Tuesday, September 30, 2008 8:34 PM
Subject: Re: Vertical South dial with horizontal gnomon - almost there!
>
> I'm getting much much closer on my date-specific south-facing vertical
> dial thanks to the help I'
Thanks to Chris Lusby Taylor and Jan afár( I think I finally got the
calculations working for my dial. I found the VBA program I was using in
Excel was inaccurate for the solar elevation and azimuth. Fortunately,
the code had an update available and that fixed the errors in my
spreadsheet. I had m
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