Why doesn't the date keep up to date on my watch?

vicwatson

I have a Citizen eco drive Titanium watch and every so often I notice the date is wrong, I don't understand how it works as how it does it know calendars/leap years etc so am I right to deduce that when it falls behind in effect I need to manually adjust it or is there a problem with it

TIA

Mr E

Is it not the case that it is rolling forward every day?
When a month has 30 days, it will always go to 31 instead of 1.

Homer

The early "calendar" watches, dating from the 16th century, were equipped with a mechanism giving the day, date and month in addition to the hour which was still imprecise at that point in time.

In a calendar watch, the days and months follow sequentially but the same cannot be said of the dates which are either 28, 29, 30 or 31 depending on the month and whether it is leap year or not. In a "simple" calendar watch, it is necessary to correct the date five times during the year, i.e. the ist day of March, May, July, October and December

Abrahain-Louis Breguet is usually credited with having invented the mechanism which made these corrections automatically.

His invention led to today's "perpetual calendar" watches as opposed to "simple calendar" timepieces. These models are based on the Julian calendar rather than the Gregorian calendar in use today. As a result, leap years are not deleted at the end of three out of four centuries, thus making it necessary to correct the watch three times in 400 years. Regarding leap years, February 29 has been deleted in the years 1700, 1800 and 1900. It won't be deleted in 2000 but will be in 2100, thus today's ads for perpetual calendar watches are right in their claims that these models will not have to be corrected for over a century. The actual duration of a year is 365.2422 days. The perpetual calendar counts the year as having 365.25 days while the simple calendar counts 12 x 31 = 372 days making it necessary to remove 6 or 7 days every year.

CALCUL

vicwatson wrote: »

I have a Citizen eco drive Titanium watch and every so often I notice the date is wrong, I don't understand how it works as how it does it know calendars/leap years etc so am I right to deduce that when it falls behind in effect I need to manually adjust it or is there a problem with it

TIA

As Mr. E and Homer pointed out, it's likely that your watch is a simple calendar rather than a perpetual calendar - meaning that it needs adjustment after any month which does not have 31 days.

It's also possible that you do have a perpetual calendar, but that it is set incorrectly - for example if the month was wrong, it may only have counted 30 or 29 days in July...

Most of the current Citizen Eco-Drive "Titanium" or "Titanium Sapphire" models feature simple calendars. There are however a few older perpetual calendar chronographs which are have a titanium case & band, and also some current higher-end pilots models, chronos, etc.

If you'd like to let us know which model you own, either here or by PM to me, I'll confirm what type of calendar it has and point you towards online instructions if relevant. You can also look up the instructions yourself online, just click here.

Thanks,
CALCUL