Message text written by David Higgon >Depending on how I understand the question, I think the answer is yes and/or no!<
I go with this answer! In a conventional horizontal dial the point on the gnomon which results in a shadow from one of the sun's rays falling on a particuar hour line will be different in mid winter than in mid summer. It surely follows that one can conceive of a profile of uneven dial plate which would result in a different hour line for these two extremes. If however the surface is planar and particularly if it slopes linearly from the root of the gnomon then it seems to me that the lines will indeed be in the same place. Not a trivial issue. Patrick
