
!Feasts  1.33 (03 Sep 2004)
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This program calculates and displays a Table of the Moveable Feasts for any year.  It is based on the tables to be found in the Book of Common Prayer.

The year may be altered either by using the 'nudge' buttons or by entering the figures directly into the icon, followed by Return, of course.  The Delete key deletes the whole year.

Although it is mainly intended for current and future use (upto 9999 AD!), it will correctly display the dates and constants back to 325 AD, the year of the Council of Nicaea, when agreement was reached, for the first time, on a unified date for celebrating Easter.  The program will not allow dates prior to this to be used, as the information given would be spurious to say the least!

When looking at the information for earlier years, the option is also included to alter the year that the change was made from the Julian to the Gregorian calendar.  The program is supplied with this set to 1752, the year that the change was made in Great Britain.  The Choice window gives three alternatives for the change - 1582 (the year the change was made in Rome), 1752 or 'Never'.  This last one is included for historical completeness as, in some Christian communities, the change was not made until the early twentieth century!

The date of Easter for the chosen year is calculated first, then the annual constants and the other dates are derived from it.   The algorithm for determining Easter is based on the one produced by Aloysius Lilius for the Calendar Commission of Pope Gregory XIII in the 16th century.  Its accuracy has been checked back to 500 AD against published sources.

For those of you who are interested in the historical aspects, the number of Sundays after Trinity and the date for Advent Sunday are correctly shown for the two change years when days were 'lost' to bring the calendar back into synchronism with the solar year.  Also in those years there was an extra Dominical (Sunday Letter) used after the 'lost' days; this is also shown in the table.  (There are, of course, two Sunday Letters used in Leap years - the first upto February 29, the second from March 1 onwards.)

This program was produced using Dr Wimp.

Subject to the conditions for distribution of the Dr Wimp library, Feasts is
released as freeware.

 Rex Palmer 2004
