A proposal for a FAQ

[Anselmo P�rez Serrada]

Hi, everyone!   Here goes a preliminary proposal for a FAQ on Sundials I'm intending to elaborate (in Spanish). I haven't seen any FAQ as such in English, if there isn't any we could make one from it if you think it's worth the effort.   Anselmo P. Serrada   PS: Sorry about my S-painful English   =============================================   ### INTRODUCTION   What is NOT a sundial? Which are the main kinds of sundials?   ### ON READING SUNDIALS   How do I read the hour in a fixed sundial? I've got one of these ring-shaped portable sundials, how does it work? I've got one of these 'box with a string' portable (ie., diptych) sundials, how does it work? I've heard about solar compasses. How are they like? What is and how does it work a refraction sundial? In a garden I found an analemmatic sundial. How can I read the hour in it? What is a bifilar sundial and how is it like? Is it true that there are digital sundials? Which are the differences between sundials in the Northern and in the Southern hemisphere? My sundial is well oriented but it doesn't give the same hour than my watch, why? What are these 8-shaped drawings you can see in some sundials?   ### ABOUT THE ELEMENTS OF SUNDIALS   What are these hyperbolae-like curves in my sundial? By the way, are these date-lines always hyperbolae? Why the device that casts the shadow has this triangular shape? Wouldn't be better just a vertical stick? I have seen a sundial that, instead of a triangle, had something like a handrail. Does it play the same role? I've been told that every sundial works properly only in one place, so sundials can't be moved to some other place, is it true?   ### ON HOURS, DATES AND SO   How many kinds of hours exist? What is exactly the 'equation of time' and how can I know its value? What is the 'daylight saving hour' and how can I include it in my sundial? Some sundials give both the hour and the date but in some others you need the date to know the hour. Why is this so?   ### ON DESIGNING AND BUILDING SUNDIALS   I would like to design my own sundial, do you know of any (free, if possible) software to draw the lines? Yes, but where do these lines come from? Which are their formulae? Now that I've got the design of the sundial, how can I build it? Do you know the address of people or companies that make sundials?   I bought one of these souvenir sundials and I do not know how to 'install' it at home. Can you help me? I have found a fixed sundial but it has lost the gnomon (ie., the 'nose'). How can I provide it with one?   ### MISCELANEA   Does a common compass suffice to know where the geographical North is? How can I know the orientation of a (vertical) wall?   How do I know which is my time-zone? How can I know which is my latitude and longitude and how much precision do I need for sundialling?   Do sundials delay as time goes by? Which is the average accuracy that an ordinary (and well oriented) sundial can yield?   Where is the biggest sundial in the world? And the eldest? And the most accurate?   I've heard about moondials. Do they really exist?   I need a motto for my sundial, can you give me some? My sundial has got a motto but I can't understand what it says. Can you give me the translation?   ### LINKS AND REFERENCES   Can you give me some good links to sundialling sites in the Internet? ...and what if I can not read English well? I just needed photos of sundials! Please, give me some references for good introductory/intermediate/advanced books on sundials! I would like to join some sundialist's association, how can I contact one? I do not like this FAQ, could you point me at some other dealing on sundials?