I thought I might share a simple drawing (URL below) that illustrates
Anselmo's idea. In the drawing the Sun is "on" the Equator so the angle
of the Solar rays onto the respective surfaces (polar dial plate and
ceiling) is 90deg. However, it can be seen that this relation holds
throughout the year. The point of the projection disappearing with
southern solar declination values, I think is valid but the extent
should vary. Still, I can't yet imagine how complete coverage can be
practically obtained. Now, I wonder further if a mirrored surface can be
described such that the hour lines are equidistant? I think I know,
anyone have any thoughts?ftp://ftp.gcstudio.com/pub/sundial/ceiling.pdf Regards, Luke
