Introduction of Gregorian Calendar - 10 days omitted

In 1582, the Julian Calendar was abolished (at least in Catholic countries) and replaced by the Gregorian one in order to correct the inaccuracy of the Julian system. As part of the transition, ten days in October were omitted from the count - October 4, 1582 was followed by October 15. So far, so good. My question is: Were the days of the week adjusted accordingly, or not? I mean, let’s assume October 4, 1582 was a Monday (I don’t know if it was). Was October 15 a Tuesday, or a Friday, as it would have been if the 10 days in between would have been counted normally?

Otherwise there would have been a problem when different countries changed system. For example when Sweden changed in 1753 the calendar was 11 days out of whack, and if the days of the week had been adjusted accordingly we would be two weekdays out of rythm, while still on the same numerical date.
For more info than you want, read the Calendar FAQ.

4 October 1582 Old Style was a Thursday, while 15 October New Syle was a Friday.

Quite apart from the fact that there was no obvious reason why the week days should change, a major consideration was that, whereas the months and the years were very obviously conventions invented by man, the seven-day week was thought to have been ordained by God.

David Ewing Duncan’s The Calendar (Fourth Estate, 1998, p290) reproduces the page from Magini’s 1582 edition of his Novae Ephemerides with the astronomical table for month of October. Both the Old and New Style dates are included alongside each other, with the latter showing the jump from the 4th to the 15th. The Sundays are marked with a “C” next to them and, as posters have been saying, remain the same day (though differently numbered) in both calendars.

Obscure geeky question coming up…

The Unix utility cal faithfully displays the break from the Julian to Gregorian calendars — as happened in the English-speaking world. If you invoke “cal 9 1752” on my machine you get:

   September 1752
 S  M Tu  W Th  F  S
       1  2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

So, that’s nifty. On the other hand, cal for October 1582 displays a perfectly normal October, because that’s just what it was. For “us”, anyway.

Now then, in the Catholic countries of Europe and Latin America, does cal place the divide in 1752 or 1582?

“Nineteen days hath September,
April, June and …” Wait a moment!? :smack:

Note that the cal utility doesn’t reflect another adjustment - England chose to adopt the “start of the year = January” convention at the same time as the Gregorian calendar shift, hence the “old style” date convention which reflected both the (by then) 11 day adjustment, and a different year for dates prior to March 21 on the old calendar. The fact that England adopted both of these reforms at the same time is one reason they get conflated in many people’s minds.

Reconciling historical European calendar dates is a non-trivial matter. Different jurisdictions adopted reforms at different times.

I suspect that the cal utility as distributed by most UNIX vendors reflects a Gregorian switch at 1752, and a naive assumption concerning the start of the year in all locales.

Russia did not convert until 1918!

Dates of adoption of the Gregorian calendar:

Note the entry on Sweden - they attempted to adopt it piecemeal, by dropping leap years until they synched up. It didn’t work out, and they wound up declaring a “February 30” one year to resynch with the Julian calendar, eventually jumping to the Gregorian calendar at a later date.

And this doesn’t even consider the “beginning of the year” nonsense, which was out of synch all over the place.

That is why the *October Revolution * is celebrated ( or at least it was in the time of the USSR ) in November

Dropping the 10 (or 11 or whatever) days resynched the calendar to what it would have been if the Gregorian had been in place since the 3rd century. Why that century and not the first (either AD when Jesus was alive or BC when Caesar established the calendar – these would be the same thing) is something I’ve never understood.

BTW, the Russians adopting the Gregorian gave rise to an interesting bit of trivia. By the 20th century, the adjustment was 13 days. The Russians decided to drop them at the beginning of February so that Jan 31 was followed by Feb 14. That made Feb 1918 in Russia only 15 days long, the shortest month ever.

This comes up from time to time. They were correcting the calendar to coincide with officially recognized astronomical observations made in the early part of the 4th century.

Both the Russian and Greek Orthodox Churches still use the " old " calender. This is why Christmas is celebrated by them on our January 6 and Easter is that much later than the other Western churches.

More specifically, to the date of the equinox (March 21) as observed at the time of the first council of Nicea in 325 AD, which established the date for Easter.

An account which mentions this:

christmas eve is jan. 6th, christmas is jan. 7th.

Then I was born on Christmas! (And so was Millard Fillmore.)