Editing Leap year (section)

===Julian reform===
In Caesar's revised calendar, there was just one intercalary day{{snd}}nowadays called the leap day{{snd}}to be inserted every fourth year, and this too was done after 23 February. To create the intercalary day, the existing {{lang|la|ante diem sextum Kalendas Martias}} (sixth day (inclusive: i.e., what we would call the fifth day before) before the {{lang|la|[[Kalends]]}} (first day) of March, i.e., what we would call 24 February) was doubled,{{sfnp|Pollard|1940|p=186}} producing {{lang|la|ante diem bis sextum Kalendas Martias}} [a second sixth day before the ''Kalends''. This {{lang|la|bis sextum}} ("twice sixth") was rendered in later languages as "[[bissextile]]": the "bissextile day" is the leap day, and a "bissextile year" is a year which includes a leap day.{{sfnp|Cheney|2000|loc=Page 145, Footnote 1}} This second instance of the sixth day before the Kalends of March was inserted in calendars between the "normal" fifth and sixth days. By legal fiction, the Romans treated both the first "sixth day" and the additional "sixth day" before the Kalends of March as one day. Thus a child born on either of those days in a leap year would have its first birthday on the following sixth day before the Kalends of March. In a leap year in the original Julian calendar, there were indeed two&nbsp;days both numbered 24 February. This practice continued for another fifteen to seventeen centuries, even after most countries had adopted the Gregorian calendar.{{citation needed|date=February 2024}}

For legal purposes, the two&nbsp;days of the {{lang|la|bis sextum}} were considered to be a single day, with the second sixth being intercalated; but in common practice by the year 238, when [[Censorinus]] wrote, the intercalary day was followed by the last five&nbsp;days of February, ''a.'' ''d.'' ''VI'', ''V'', ''IV'', ''III'', and {{lang|la|pridie Kal. Mart.}} (the days numbered 24, 25, 26, 27, and 28 from the beginning of February in a common year), so that the intercalated day was the ''first'' of the doubled pair. Thus the intercalated day was effectively inserted between the 23rd and 24th days of February. All later writers, including [[Macrobius]] about 430, [[Bede]] in 725, and other medieval [[computus|computists]] (calculators of Easter), continued to state that the bissextum (bissextile day) occurred before the last five&nbsp;days of February.{{citation needed|date=December 2022}}

In England, the Church and civil society continued the Roman practice whereby the leap day was simply not counted, so that a leap year was only reckoned as 365&nbsp;days. [[Henry III of England|Henry III]]'s 1236 {{lang|la|[[Statute De Anno et Die Bissextili]]}}{{efn|''Statute concerning [the] leap year and leap day''<br />The day of the leap year, and the day before, shall be holden for one day.<ref name=Bissextili>{{citation |last1=Ruffhead |first1=Owen |title=The Statutes at Large, from Magna Charta to the End of the Last Parliament |date=1763 |publisher=Mark Basket |page=20 |url=https://archive.org/details/statutesatlargef01grea/page/20/mode/1up |access-date=21 October 2021}} (21 Hen, III)</ref>}} instructed magistrates to treat the leap day and the day before as one day.<ref name=Bissextili />{{sfnp|Cheney|2000|loc=Page 145, Footnote 1}} The practical application of the rule is obscure. It was regarded as in force in the time of the famous lawyer Sir [[Edward Coke]] (1552–1634) because he cites it in his ''[[Institutes of the Lawes of England]]''. However, Coke merely quotes the Act with a short translation and does not give practical examples.
{{blockquote|text= ... and by (b) the statute {{lang|la|de anno bissextili}}, it is provided, {{lang|la|quod computentur dies ille excrescens et dies proxime præcedens pro unico dii}}, so as in computation that day [[wiktionary:excrescent|excrescent]] is not accounted.<ref>{{cite book | title = First Part of the [[Institutes of the Lawes of England]] | date = 1628 | chapter-url= https://archive.org/details/firstpartofinsti011628coke/page/116/mode/1up?view=theater | chapter = Cap. 2, ''Of Villenage'' | page = [https://archive.org/details/firstpartofinsti011628coke/page/n287/mode/2up?view=theater 136 left (Sect. 202, line 3)] | first = Edward |last=Coke | author-link = Edward Coke }}</ref>}}