In case it didn't come through before, here is Judy Young's clear answer,
for which I am grateful.
John Schilke
>
> Dear John and the List,
>
> Thanks for the question. You are the second person to ask in 2
> days how to determine the day of the solstice, given the slow change in
> the Sun's declination. The answer is not complicated, just clever.
>
> It would take observations over several years to determine the day
> of the solstice (this is described in Ray Williamson's book LIVING THE
> SKY). One year, some people would have had to notice the extremes of the
> Sun's location along the horizon in terms of the rising and setting
> directions, noticing the northern and southern extremes of sunrise and
> sunset. The next year, the astronomers would have had to watch more
> carefully. They would mark a spot along the horizon where the Sun rose
> or set, about a month before solstice, and they would count how many days
> passed before the Sun returned to that same sunrise or sunset location,
> about a month after solstice. They would divide that number of days in
> half, and remember it for the next year. Finally, in the 3rd year
> of observation, when the Sun reached the spot marked the previous
> year, the astronomers would count the days to the Suns's southernmost
> point, and that would be the rising or setting location for the
> winter solstice. One would need clear skies for this, or it would take
> considerably more than 3 years.
>
> There were possibly other ways to determine the day of the solstice as
> well, but this method could easily have worked.
holidays and happy winter solstice to you and your loved ones.
>
> Sincerely,
> Judy Young
