Fer,
Here is, I think, the message Mac mentioned.
Bill
---------- Forwarded Message ----------
From: "fer j. de vries", INTERNET:[EMAIL PROTECTED]
TO: "Shadow Maker", INTERNET:[EMAIL PROTECTED]
"sundial", INTERNET:sundial@rrz.uni-koeln.de
DATE: 3/26/01 7:21 AM
RE: Re: Reclining/Declining
Hello Robert,
Calculating the angles for the hourlines isn't complicated if the dial is
translated to an equivalent horizontal sundial.
Start to calculate 3 angles:
sin v = sin phi . cos i - cos d . cos phi . sin i
v is the style height and also the equivalent latitude where the dial is
horizontal
sin b = cos phi . sin d / cos v
b is the angle of the substyle, relative to the line of greatest slope.
With v and b it is known where the polestyle will be.
tan ts = sin i . sin d / ( cos phi . cos i + sin phi . sin i . cos d )
ts is the hourangle at what time the shadow of the style falls on the
substyle.
Use ts as a longitude correction to calculate the horizontal dial at
latitude v.
Use the usual formula for an horizontal dial
tan z = tan t . sin v in which t is corrected for longitude ts.
z is the angle of the wanted hourline relative to the ( known ) substyle.
Correct values for b , ts and z to the right quadranr if necessary.
I think this is the easiest way to do the job.
Best wishes and happy dialing, Fer
Fer J. de Vries
[EMAIL PROTECTED]
http://www.iae.nl/users/ferdv/
Eindhoven, Netherlands
lat. 51:30 N long. 5:30 E
----- Original Message -----
From: Shadow Maker <[EMAIL PROTECTED]>
To: <sundial@rrz.uni-koeln.de>
Sent: Friday, March 23, 2001 6:58 PM
Subject: Reclining/Declining
> I have built some horizonal, vertical and vertical/declining dials and I
am
> now ready to build a reclining/declining dial, that will compensate for
> standard time (that part is easy).
>
> I have read what Mayall/Mayall, Waugh and Rohr have written about the
> layout process. I would prefer to use the trig formulas for SD, SH and
> HourAngles because I can use them in a PostScript file that will render
the
> dial face and print out the values of all of the angles. Rohr does show
the
> formulas for SD and SH but, like the others, he recommends a graphic
layout
> method instead of a computational method
> for the hour line angles. I was hoping that all of the trig formulas would
> be available, but can't find them. Waugh says that older editions of the
> Encyclopedia Britannica had all the trig formulas but dropped them a
hundred
> years ago.
>
> Can anyone help?
>
> Robert Hough
> [EMAIL PROTECTED]
>
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn.com
>
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Message-ID: <[EMAIL PROTECTED]>
From: "fer j. de vries" <[EMAIL PROTECTED]>
To: "sundial" <sundial@rrz.uni-koeln.de>,
"Shadow Maker" <[EMAIL PROTECTED]>
References: <[EMAIL PROTECTED]>
Subject: Re: Reclining/Declining
Date: Sun, 25 Mar 2001 15:21:58 +0200
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