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 > > east of south anyway, and the location where the > dish is gets > > direct sunlight almost all year round. > > > > > > > > My questions is this: Do I need to make any > adjustment in the > > calculations of the hour lines for the shape of > the dish? If so > > what is the formula? > > > > > > > > I am going to install a simple style using a metal > road about a > > half inch in diameter. I want this sundial to > tell solar time not > > necessarily actual time. Though one day I may > install an equation > > of time underneat the dial . > > > > > > > > Boardwalk for $500? In 2007? Ha! > > Play Monopoly Here and Now (it's updated for > today's economy) at > > Yahoo! Games. > > > > > --------------------------------------------------- > > > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
