Simpler Roman Calendars

If we were to simplify the Roman calendar (Gregorian/Julian), we’d

• put the leap day at the end of the year
• put the days of the months into a regular pattern
• that also made it easy to group months into
  • regular quarters of 3 months of 91 days
    (13 weeks + new years day & leap day)
  • and sixths of 2 months of 61 days (-non leap day)

If we were to simplify the Roman calendar (Gregorian/Julian) so that leap days only occurred at the end of the year, we have two main options:

Move the end of the year

… to where leap days occur. Keep February as the month with the leap day.
This has the advantage of restoring the *embers to their ordinal location.
September becomes 7th month, … December becomes 10th month.

While we’re at it, to make the calendar more regular,
let’s make February longer with a day from August and a day from January.

Move the leap day

… to the end of the year. So, make 31st December the leap day.
While we’re at it, to make the calendar more regular,
let’s move a day from July to February to make it 30 days.

Notation

* Leap day is included in count of months and sixths.
+* Leap day is excluded in count of days in fourth quarter.
+ New Years Day is excluded from count of days in first quarter.

Alignment

This table shows the alignment of Simpler Roman Calendars with Gregorian calendar, where all use the day month patterns as above and either:

1. Move year end to leap day (Start 1 March)
2. Move leap day to year end (end 30/31 December)
   • 60 days earlier, in preceding calendar year
   • 306 days later, in same calendar year
3. Move leap day to year end
   • near vernal equinox (to 20/21 March)
     • ~20 days later
   • near southern solstice (to 21/22 December)
     • ~70 days earlier
     • ~296 days later.

References

Some table data and layout from : https://en.wikipedia.org/wiki/Calendar_reform