Greetings!
It occurred to me today that I probably do not fully understand something
that would be of interest to the List. Granted the difficulty of
determining the equinox, using only a dial or a Stonehenge-like ring (mainly
because of the rapid change in solar declination), I thought about the
opposite problem. How does one, using either of these tools only, determine
the time (i.e., epoch) of the solstice, since the declination of the sun
changes very little over several days -- only a couple of minutes of arc
daily.
I've pencilled out some intriguing possibilities, but they all depend on
19th and 20th century math and astronomy. How did the ancients do it?
I'm probably looking right at the answer and shall feel quite silly when it
is shown to me, but I still will ask. Thanks for the help.
John F. Schilke, MD
Oregon City, Oregon, USA
122W36, 45N21
