William Wedemeyer asks about possible sundials for a known location but unknown north. Can we presume, then, that the dial is to be portable? There are many possibilities, of which he mentions several.
The ring dial's main attraction is its extreme portability and ruggedness. As an accurate timepiece it is very limited. The pillar dial is somewhat better. It can be made accurately for a known latitude, but only by much calculation. As a brilliant piece of geometry which requires almost no calculation, I like the Capuchin or ship dial. It is very portable and quite robust. The small "armillary spheres" which he mentions are actually small equatorial sundials. These are very satisfactory. They are truly universal (can be used anywhere), potentially quite accurate, and show the direction of north. They also, with a little thought, show where and when the sun will set, which can be useful. With several moving pieces, they are perhaps less robust. The ideal carrying case is in the form of a ring which serves as a base when the sundial is in use. The analemmatic pair (an analemmatic plus a horizontal) is less portable, not universal (it must be made for a specific latitude) and less intuitively easy to use. In my view it is a scientific curiosity with few practical merits. Indeed, I have calculated that there are other pairs of dials that make a better combination. Any more ideas, anyone? Regards Chris
