Fred,
Thank you for offering an answer to my original inquiry i.e., "Namely
who, when and by what means was the analemma 'discovered'. Surely some
form of regular timepiece must have been used, was it indeed some form
of water clock?" The reference to analemma being, as clarified earlier,
the graph of (eot vs dec). Perhaps you can offer the highlights of this
historical discovery to the list?
Also, in looking through my newly purchased copy of "Early Physics and
Astronomy" by Olaf Pedersen, Ptolemy's "On the Analemma", is described
as providing a fundamental theory of sundials using orthogonal
projection. Ptolemy's "On the Analemma" might well read "On the Sundial"
and deals with the theory of a specific sundial construction technique
and not about the equation of time or its graph. Interestingly enough,
Ptolemy also wrote in his "Planisphaerium" a mathimatical theory for the
astrolabe using of course, stereographic projection.
Regards,
Luke
