Easter dates

In uk.sci.astronomy message , Mon,
25 Feb 2008 01:07:27, Dentist posted:
Dr J R Stockton wrote;
No 15-year period is used in the calculation of Julian or Gregorian
Easter.
sigh
The method used by Jens Olsen does. Otto Mortonsen calls it the cycle
of indiction. It's period is 15 years. My post was about the book. What
is difficult here?

If the 15-year Indiction period is used in the calculation of Easter,
then either it is used in a manner which has no ultimate effect or the
result is wrong. Perhaps the book is wrong, or misleading.

I expect that the clock shows both the Indiction and Easter, but that it
does not use the former to find the latter.

It is true that the Easter repeat interval, 5,700,000 years, is
divisible by 3*5 = 15; 5,700,000 is made up of 19 * 25 * 30 * 400, where
the 30 corresponds to the length of a Lunar Month. Consult the Preface
to the Prayer Book : Table III has 30 rows of numbers, one row being in
two parts.

--
(c) John Stockton, nr London, UK. Turnpike v6.05.
Web URL:http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms
PAS EXE etc : URL:http://www.merlyn.demon.co.uk/programs/ - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.

Dr J R Stockton wrote;
If the 15-year Indiction period is used in the calculation of Easter,
then either it is used in a manner which has no ultimate effect
You are correct and I apologise.
The calendar work of the clock computes and adjusts the calendar for the
year, movable and fixed feasts, the days of the week on their correct
dates, and shows the dominical letter, epact, solar cycle, cycle of
indiction and lunar cycle. The adjustment for Gregorian leap years is
derived from a differential gear train which also happens to drive the
indiction train.
I had become accustomed to thinking of the calendar work as a whole,
rather than the Easter mechanism in particular. The calendar is of the
perpetual type, and calculates correctly.

I expect that the clock shows both the Indiction and Easter, but that
it does not use the former to find the latter.

--
Denis

On Feb 26, 3:13*am, Dentist wrote:
Dr J R Stockton wrote;If the 15-year Indiction period is used in the calculation of Easter,
then either it is used in a manner which has no ultimate effect

You are correct and I apologise.
The calendar work of the clock computes and adjusts the calendar for the
year, movable and fixed feasts, the days of the week on their correct
dates, and shows the dominical letter, epact, solar cycle, cycle of
indiction and lunar cycle. The adjustment for Gregorian leap years is
derived from a differential gear train which also happens to drive the
indiction train.
I had become accustomed to thinking of the calendar work as a whole,
rather than the Easter mechanism in particular. The calendar is of the
perpetual type, and calculates correctly.



I expect that the clock shows both the Indiction and Easter, but that
it does not use the former to find the latter.

--
Denis

Thank God my astronomical timekeeping ancestors were imaginative in
creating the 24 hour clock system apart from the calendrical outrigger
until a silly man (Flamsteed) decided to use timekeeping astronomy to
dictate structural astronomy.It is fortunate that you pair have'nt the
faintest idea beyond you calendrically driven clockwork solar system
but then again,it was you kind who wrecked astronomy,if not by
telescope then by an uncouth attachement to the Ra/Dec system.

Your countryman was right -

"Now, in the former part of this book, I have treated about matters
pertaining to the strictness of measuring time; and have shewn the
deficiencies of such means as Mr. Graham had taken or made use of for
that purpose; and I have also treated of the improper, troublesome,
erroneous - tedious method, which the professors at Cambridge and
Oxford would have to be for the longitude at sea:" John Harrison

Most people believe that Harrison triumphed in gaining recognition for
his inventive achievement of the chronometer attached to the
principles of 24 hours/360 degrees but one look at the tedious posting
in a half dead newsgroup shows who the true victors were.It is fine to
create a hybrid celestial sphere navigation program or a convenient
way to gauge celestial objects against the celestial sphere background
but the wretched numbskulls took it further and made the system
obligatory for structural astronomy.

Another of you countrymen perfectly portrayed how you are mesmerised
by your own pretensious endeavors on paper leaving the background sky
bare -

http://www.nimbi.com/william_blake_newton.html

Like Harrison's achievement,they now have Blake lauding Newton as a
'Divine geometer' when Blake's picture is pretty explicit to the
position Newton holds - something like yourselves.

Uk.astronomy indeed !, more like surburban mediocrity which Blake
predicted.

"Dr J R Stockton" wrote in message
nvalid...
In uk.sci.astronomy message ,
Sun, 24 Feb 2008 09:52:19, Mike Dworetsky .
com posted:

The Roman Indiction period of 15 years was for taxation calculations,
and was introduced by Constantine the Great in 312AD. Or so it says in
the Calendar FAQ.

It is also used in the construction of the Julian Day Number.

No. It is used, but it is not also used; it plays no part in the
calculation of Julian or Gregorian Easter. It is one of the three
cycles which jointly were, extrapolating back, at zero in B.C. 4713;
JDN 0.0 is proleptic Julian BC 4713-01-01 noon GMT.

The FAQ by Claus T¢nderings has an extensive section on calculating the
date of Easter.

http://www.tondering.dk/claus/cal/calendar28.html

But the FAQ shows no evidence of traceability to the Calendar Act,
Clavius, or legal authority elsewhere (though the algorithms are
correct).


Indeed, the original poster seemed to be asking about the Indiction as used
in the Olsen clock, not about calculating Easter specifically. I suspect
the 15 year period is in the Olsen clock simply because there are references
to it being used in civil applications until c. 1800. But the Indiction has
nothing to do with Easter--and I don't think I specifically said this,
though my use of the word "also" may have more than one interpretation. My
take on it is that I said it was used for tax cycles and was *also* used in
constructing the Julian day number scheme.

The 19-year Metonic cycle, on the other hand, does find a use in calculating
Easter. It also shows up in the Antikithera mechanism, if I am correctly
remembering the articles on the recent analysis of this. Whatever "also"
means anyways, to paraphrase.

--
(c) John Stockton, nr London, UK. Turnpike v6.05
MIME.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms &
links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm,
etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail
News.


--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

In uk.sci.astronomy message ,
Wed, 27 Feb 2008 22:31:00, Mike Dworetsky .
com posted:

The 19-year Metonic cycle, on the other hand, does find a use in
calculating Easter. It also shows up in the Antikithera mechanism, if
I am correctly remembering the articles on the recent analysis of this.
Whatever "also" means anyways, to paraphrase.

Indeed. The nineteen full moons of the Metonic Cycle were evenly
distributed, at a substantially constant interval un-mod 30, over the 30
days starting at the nominal Equinox, and the Sunday next following was
Easter. That 19 combined with the 28-year cycle of the secular
calendar, and gave (as known by Bede) a 532-year period for the dates of
Easter.

Then Clavius complicated everything, but preserved the foundation.

Which, alas, has now been lost by those who should know better - q.v.:

--
(c) John Stockton, nr London, UK. Turnpike v6.05.
Web URL:http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms
PAS EXE etc : URL:http://www.merlyn.demon.co.uk/programs/ - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.