Originally Posted by minder
Since the op wants to use the Julian calendar then 1900 is a leap year. My understanding is that in the Julian calendar the only criteria for a leap year is that it be divisible by 4.
Yes. The Julian system is "more or less" 365.25 days system with a whole bunch of odd things that happened to it. The gregorian system is 365.2425 or some where close to that, making only centuries divisible by 4 leap years, removing 3 days out of the overall cycle.
The reason for the change was to get the seasons right. The reason I need this is for personal use to convert dates between 3 systems (or perhaps more if I come up with needing more) Some of the systems care about keeping seasons right and some don't. The calenders are for a conworld and I am going with the conceit that the world has a perfect 365.25 year. That way i can make it simple but still keep it close to reality. It's a nice little compromise.
I'm also having a hard time with one of the other calenders cuz it's weird... each week has 7 days and each of month 7 weeks and there are 7 months. At the end of 7 years there is a year of 7 months of 21 days and then a "non" year of 9 days. This system and the Julian system lines up every 28 years having the same number of days. I thought that that would make it easier to calculate longer scale numbers but, meh, i still don't like doing it.