John yes, the polar axis aligned style would generate the dial center and thusly the hour lines. Heck I did that with one of my large wall dials where the wall was an irregular surface. Duh.
Good to know I am not the only one not thinking well today:) Simon --- John Carmichael <[EMAIL PROTECTED]> wrote: > Hi Simon: > > Thanks for confirming that the empirical method > autocorrects for longitude > shift. > > You wrote: > However, unless I am more than usually dense today, > it > provides hour points for a given declination, not > hour > lines. > > I think that if the gnomon is a polar axis rod (not > a perpendicular one)or > if it is a triangular sheet, then the shadow of the > rod or the top edge of > the sheet WILL fall on the hour lines. > > John > > p.s. My brain isn't working all that well either as > I just returned from > Italy yesterday. Those Italian PWS are FANTASTIC > and so is the whole > country! So much art everywhere, I was overwhelmed > by it all. Mario Arnaldi > and Mario Catamo gave me personal tours of their > dials. What great guys > they are.) > > > > -----Original Message----- > From: Simon [illustratingshadows > [mailto:[EMAIL PROTECTED] > Sent: Thursday, June 21, 2007 1:34 PM > To: Willy Leenders; John Carmichael > Cc: 'Sundial List' > Subject: Re: Direct South Dial > > John's method does mark legal time and thus does > consider longitude. > > However, unless I am more than usually dense today, > it > provides hour points for a given declination, not > hour > lines. > > However, it has been a long day, so I may simply be > denser than usual:) > > Simon > > --- Willy Leenders <[EMAIL PROTECTED]> > wrote: > > > Hi John, > > > > Using your empirical method, not only the equation > > of time must be > > zero, you have to take in account the correction > for > > longitude. > > > > Willy Leenders > > Hasselt in Flanders (Belgium) > > > > Op 21-jun-07, om 21:24 heeft John Carmichael het > > volgende geschreven: > > > > > Hello Andrew: > > > > > > > > > > > > There is an easy way to mark the hourlines on a > > satellite dish or > > > any surface for that matter, without using any > > formulas or math. > > > Use what some call the empirical method. This > > method is useful > > > for oddly shaped surfaces. > > > > > > > > > > > > 1. Position the dish in the direction that you > > want it to face. > > > (Due south or even slightly away from south. It > > doesnt matter.) > > > > > > 2. Attach your gnomon so that the shadow casting > > edge points > > > directly at the north celestial pole (Youll > > probably attach it at > > > the center of the dish, and you will probably be > > using a rod > > > gnomon, but it could be attached anywhere. It > > doesnt matter). > > > > > > 3. On a sunny day, when the Equation of Time is > > zero (the next date > > > this occurs is September 1st), using an accurate > > time source, mark > > > where the gnomons shadow falls on the dish at > the > > times you want > > > to indicate (hours, ½ hours, ¼ hours, whatever). > > > > > > 4. Done! > > > > > > > > > > > > Your sundial will now indicate solar time > adjusted > > for longitude. > > > > > > > > > > > > You can mark your sundial in the same fashion on > > any day of the > > > year if you take into consideration the Equation > > of Time value for > > > the date that you do it. > > > > > > > > > > > > Real easy! > > > > > > > > > > > > John L. Carmichael > > > > > > Sundial Sculptures > > > > > > 925 E. Foothills Dr. > > > > > > Tucson AZ 85718-4716 > > > > > > USA > > > > > > Tel: 520-6961709 > > > > > > Email: [EMAIL PROTECTED] > > > > > > > > > > > > > > > > > > My Websites: > > > > > > (business) Sundial Sculptures: > > http://www.sundialsculptures.com > > > > > > (educational): Earth & Sky Equatorial Sundial: > > http:// > > > advanceassociates.com/Sundials/Earth-Sky_Dial/ > > > > > > (educational) My Painted Wall Sundial: http:// > > > www.advanceassociates.com/WallDial > > > > > > (educational) Painted Wall Sundials: > > http://advanceassociates.com/ > > > WallDial/PWS_Home.html > > > > > > (educational) Stained Glass Sundials: http:// > > > www.stainedglasssundials.com > > > > > > (educational) Sundial Cupolas, Towers & > Chimneys: > > http:// > > > > StainedGlassSundials.com/CupolaSundial/index.html > > > > > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] > > > koeln.de] On Behalf Of Andrew Corl > > > Sent: Thursday, June 21, 2007 10:27 AM > > > To: Sundial List > > > Subject: Direct South Dial > > > > > > > > > > > > Greetings all, > > > > > > > > > > > > Several months ago I bought a house and the > > previous owners left me > > > with one of those 12" diameter satellite dishes. > > > I have no need or > > > want of Direct TV or satellite TV. > > > > > > > > > > > > I was sitting there thinking one day that it > would > > make a really > > > nice direct south facing sundial. My house > > already faces a little > === message truncated === --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
