The declination curves center on the SD derived using the wall declination.
With a gnomon such as is discussed here, there is no SD because the substyle is 0 degrees from vertical. With this dial, the real derived SD is still needed for the centering of the calendar curves. Simon --- On Fri, 9/12/08, Chris Lusby Taylor <[EMAIL PROTECTED]> wrote: > From: Chris Lusby Taylor <[EMAIL PROTECTED]> > Subject: Re: 'Folded' Gnomon Declining dials? > To: [EMAIL PROTECTED], "Sundial List" <[EMAIL PROTECTED]>, "Patrick Powers" > <[EMAIL PROTECTED]> > Date: Friday, September 12, 2008, 9:29 AM > I don't see why deriving declination/calendar curves is > affected in any way. > The nodus position, measured along the style from the root > of the gnomon, is > the same. > It would, certainly, be wrong to measure the nodus height > by using its > distance perpendicular to the foot > of the gnomon, but it's more accurate to measure along > the gnomon in any > case. > > Chris > > > > ----- Original Message ----- > From: "Simon [illustratingshadows" > <[EMAIL PROTECTED]> > To: "Sundial List" > <[EMAIL PROTECTED]>; "Patrick Powers" > <[EMAIL PROTECTED]> > Sent: Friday, September 12, 2008 3:30 PM > Subject: Re: 'Folded' Gnomon Declining dials? > > > This method described is one popularised by Dolan. The > advantage is that > SH=design lat, and there is no SD. The disadvantage is that > deriving > declination/calendar curves is more involved. > > Simon > > > --- On Thu, 9/11/08, Patrick Powers > <[EMAIL PROTECTED]> wrote: > > > From: Patrick Powers > <[EMAIL PROTECTED]> > > Subject: 'Folded' Gnomon Declining dials? > > To: "Sundial List" > <[EMAIL PROTECTED]> > > Date: Thursday, September 11, 2008, 4:57 PM > > There is an unusual East Declining Vertical Dial on > the side > > of the > > Cathedral (Catedral de Santa María de la Sede) in > Seville > > (Sevilla) in > > Spain. > > > > It has a gnomon which is 'folded' from the > Noon > > line rather than being > > placed orthogonal to the dial plate along the > sub-style > > line as is more > > usual,. This dial must decline by around 50 degrees to > the > > East. > > > > As far as I know there is only one dial of similar > > construction here in the > > UK (it is SRN 1279 in Hertfordshire) - though there > may be > > others - and as > > a consequence this form of construction has in Britain > at > > least, been seen > > as a rather 'amateurish' form of design. > > > > However having found this dial in Seville the question > > arises: Is this > > form of gnomon construction more common than I > thought? > > Are there more > > instances of this form of gnomon design elsewhere and > have > > they been > > produced by what nowadays would be regarded as > > 'professional' designers? > > > > The Seville dial and the one known in the UK may be > seen at > > > > > > http://tinyurl.com/4x24my > > > > Many thanks for any comments > > > > Patrick > > > > > > > > > > --------------------------------------------------- > > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
