Advice requested - Julian Calendar.

[SiGr]

Hi,

I would be grateful for some advice on the Julian calendar if anyone can help.

My understanding is that until 1751/2 the day after, for example, 24 March 1629 would be 25 March 1630.

However, when I use a calculator such as:

https://www.timeanddate.com/date/durationresult.html?d1=28&m1=2&y1=1629&d2=1&m2=5&y2=1630

and ensuring I set it to 'Julian calendar in the UK'

to work out the number of days between 28 Feb 1629 and 1 May 1630, it tells me the answer is 427 days. Yet surely it should just be 62 days ?

I'm obviously missing something simple but I can't see what.

Can anybody tell me where I am being a muppet on this, please ?

Thanks in advance for any suggestions/comments/solutions.

Simon

[billnkempsey]

Not a muppet, at least, you're not the muppet.

I suspect that nobody told the programmer for the calculator that the change of year hasn't always been 31 Dec-1 Jan. Or, possibly, they weren't told exactly when that wasn't the case.

The value you got, 427, is exactly 365 more than you expected. That is, the new year didn't occur, for the calculator, until after Dec 1629.

Find a new calculator, is my advice. (Or remember this and subtract, or add, 365 when needed. But that's a pain.)

[billnkempsey]

For advice, I tend to use calculators created for astronomy, specifically a good Julian Date calculator, for example:
https://apps.aavso.org/v2/tools/julian-date-converter/

These convert to an odd number of days (specifically, the number since 1 Jan 4713 BC, don't ask).

For your example, the difference is 62 days, as expected.

However, for the period when much of Europe had a different calendar to England, you still might need to be careful.

And this ignores all the other perfectly valid calendars used around the world and through time.

[SiGr]

Hi, billnkempsey,

A big 'thank you' for both your posts and confirming I hadn't misunderstood the calendar change.

I'll also heed your advice to try other sites next time.

ATB

Simon