# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: using old nautical almanacs
From: Herman C
Date: 2009 Mar 15, 10:39 -0700

```Bill

This is slightly off topic bur nevertheless pertains to leap year
calculation.
Bill wrote
"In either case, baring surprises, the current leap years system seems
to be
good for thousands of years before it runs into trouble."

It looks like the current Gregorian calendar leap year rule is good
for 40,000 years and beyond. But sometime between 10,000 and 40,000
years if one leap year is eliminated then the number of days would be
365.24225 days which is more closer to desired 365.24222.

First cycle
Years   days    Total   Average
3   365 1095
1   366 366
4       1461    365.25000

2nd Cycle
303 365 110595
97  366 35502
400     146097  365.24250

3rd cycle
3,031   365 1106315
969 366 354654
4,000       1460969 365.24225

4th cycle
30,311  365 11063515
9,689   366 3546174
40,000      14609689    365.24223

Also the Orthodox Church in 1923 when they synched their calendar with
Gregorian calendar, adopted a different leap year rule.This leap year
rule was proposed by the Serbian scientist Milutin Milankovi�, an
astronomical delegate to the synod representing the Kingdom of Serbs,
Croats and Slovenes.Years evenly divisible by four are leap years,
except that years evenly divisible by 100 are not leap years, unless
they leave a remainder of 200 or 600 when divided by 900, then they
are leap years.Milankovi� selected this rule, which produces an
average year length of 365.242222... days, because it was within two
seconds of the then current length of the mean tropical year.(http://
en.wikipedia.org/wiki/Revised_Julian_calendar)
According to Orthodox Church calendar, Years 2900 and 3300 would be
leap years instead of 2800 and 3600.

So followers of Orthdox Church may have buy new NA's in year 2800.

Herman D.

On Mar 12, 3:51 am, Bill  wrote:
> George wrote:
> > It would be nice if a mailing list such as ours offered a way to draw
> > attention to an acknowledged mistake, after it has appeared. Not to allow a
> > posting to be amended after the event, which could be dangerous tinkering
> > with history, and never-ending. Instead, to allow the original contributor
> > (and nobody else)  to retrospectively add a tag which means, in effect- "the
> > writer of this posting asks you to read it in context with later message
> > number [xxxx] which will modify it in some way". I fear that I would use it
> > often.
>
> LOL. The famed "unsend" key!  And wouldn't it be dandy if print and
> broadcast media that made a typo--or worse yet a fact-checking error (which
> I have been guilty of on the list, as well as a major US of A network some
> years ago)--could recall and reissue the publication instead of burying the
> retraction of their mistake somewhere in the dark corners of the
> publication?
>
> One of the downsides of a group such as ours is the lack of professional
> proof readers and fact checkers. The author is naked.  On the upside, we can
> express an international smorgasbord of knowledge and opinions in almost
> real time.  If someone is interested in a topic discussed days, months, or
> years ago Robert and Frank have made that information available.  Like a
> prudent navigator using all available data, I would hope one would read and
> consider the entire thread/topic instead of taking one post as gospel and
> note any errata posted.
>
> In my mind it is as simple as following up a post with a factual/non-fatal
> grammatical error with a "PS" or "Error" message. Addressing the "If wishes
> were fishes, our nets would all be full" portion of your posting, I too
> abhor revisionist history, and such a feature would be handy. And if you can
> imagine it, it can probably be done.  Perhaps not tomorrow ;-)
>
> Bill B.
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