Dear Doug,
The answers to your first question about
noting seasonal drift 1000 years ago have
all missed something crucial...
The astronomical comments have been very
sound but what is missing is any account
of just how you would maintain your
records?
These days you could buy a desk-top diary
and write your observations in it on a
daily basis. I would like to know how
people did that 1000 years ago, never
mind in Babylonian times.
You need to have invented a calendar and
some form of writing implement and you
need to be able to count.
The Babylonians had this infra-structure
but their calendar had intercalary months
which were added ad hoc. I would have
found this hard to live with!
Even if think about the relatively recent
times of just 1000 years ago you would,
today, have headed your entry:
a d IX kal Mart MMXVII
and you would need to be able to work out
what the date was CCCLXV days ago.
In doing your calculations you have the
added difficulty that zero hasn't yet
been invented. Fractions are understood
but expressing results to a certain
number of decimal places is way into
the future.
I have often pondered an even more primitive
question: I am dumped on a desert island and
I want to count the days since I arrived.
What discipline should I follow?
I could, of course, cut a notch in a stick
every morning when I first wake up but
what happens when one day, around noon, I
think "Oh, er, did I cut today's notch?"
I am by no means convinced that I could
reliably count up to CCCLXV.
Can someone please come up with an
error-detecting and error-correcting
approach.
I am not sure I understand your second
question:
Assuming that in 1850s I had access
to a good transit telescope, and a
reasonable clock (daily errors
about 1 second a day)...
Like you, I don't see why the clock
needs to be all that precise in a fixed
observatory. You can put it right on
a daily basis using your transit
telescope.
Of course you wouldn't actually adjust
the clock, you would just log the error.
Indeed, by the 1850s, star tables were
sufficiently good that you could have
logged the error several times a night!
Frank
---------------------------------------------------
https://lists.uni-koeln.de/mailman/listinfo/sundial
