Re: Ring dial corrections between latitudes

[Mike Cowham]

Dear Fer,     Yes, you are right.  Sorry for the false information.  I was only thinking in two dimensions, not three!  As you say, it is possible but inconvenient.  Gravity make a mess of everything! Regards, Mike Your statement about using a sundial at another place is correct for usual dials to read time and date lines because the type of lines are based on the same coodinate system "hourangle, declination". This won't work for e.g. Babylonian, Italian, antique hours, only for usual hours.   But it won't work for a ring dial that hang by a cord. At the new place the used coordinate system "azimuth, altitude" is different.   Or you should "hang" the dial at a line parallel to the vertical of the original spot. This is rather clumsy for a portable ringdial.   Just replacing the suspension point won't work. It still hangs parallel to the vertical of the new place and not parallel to the vertical of the old spot.