🚀 go-pugleaf

Alison writeth:
>I am dead certain that the line on a sundial will *not* fall on a single
>line at sunrise throughout the year. 

>Why? Because the earliest "sundials" (like Stonehenge, the Serpent Mound here
>in the US, etc, etc.) were made not to tell time of day, but time of year. 
>Strategically placed holes/slits etc. were positioned so that the light from
>the sun at sunrise would fall in an alcove/bisect a spiral carved in rock/
>be contaoined completely within a curve/or whatever. This would simply be
>impossible if the sunrise location did not move.

Hmmmm.  This is indeed true.  However, I am also sure that a Roman-type
sundial works the way I described before, namely that it worked throughout
the year with the same set of markings.  I think it has something to do
with the angle of the diagonal side of the gnomon being adjusted for
latitude.  It may be that the shadow of the straight side varies by time of
year but not the shadow of the angled side....?

			---Simon