The World's Most Complicated Watch - getting the dates right

And yet another hint for you my dear Loungers.

We were up in the sky with the celestial sky chart but let's get back dwn to earth and some serious business.

Vachern Constantin's "Grand Oeuvre" or "Opus Magnum" features another world first: dual calendar mechanism with two separately functioning yet mechanically integral options that can be read at the same time – the traditional Gregorian perpetual calendar with 12 months, 52 weeks and 7 days and at the same time, the business calendar system known as ISO 8601.

And considering how complicated it is to explain i can only fathom how complicated it must have been to concieve in a mechanical watch!

This is the first time ever that the ISO 8601 calendar has been made as a watch function, its creation and incorporation as one half of the dual calendar system has required not only extremely complex calculations, but the practical ability of the Vacheron Constantin watchmakers to design and translate their theory into a working and easily readable function.

The Gregorian perpetual calendar which automatically corrects itself for the appropriate number of days in the month and the leap-years employs a retrograde date display, days of the week and months dials and a leap-year window displaying a number between 1 and 4 in the leap-year cycle.

The ISO 8601 business calendar is a specific system founded by the International Organization for Standardization for use mainly in the international financial sector and divides the year into weeks. The First week of January being week one and so on.

When the ISO 8601 mode is employed, the number of the week within the year and the number of the day within the week takes precedence over the traditional calendar month and traditional date, the number of the week is read from the dial concentric to the month indication and the number of the day within the week is indicated by a number between 1 (for Monday) and 7 (for Sunday) in a window directly above the week dial.

The ISO system has a full cycle of 400 years and employs a seven day cycle with weeks starting on a Monday. However, an ISO year can have either 52 or in some cases 53 full weeks when New Year’s Day falls on a Thursday (Wednesday or Thursday in leap-years), this occurs every 5 or 6 years. In the ISO calendar, week 1 is the one which contains the first Thursday of the year and always contains January 4th.

The last week of the year in the ISO calendar is the one that contains the last Thursday and always includes 28th December. This system requires the user to adopt a different way of interpretation, for example: if the calendar is displaying Thursday, September 17th, the ISO calendar wthe ISO calendar will read as day 4 in the aperture (because Thursday is the fourth day) and week 38 on the week dial.

The World's Most Complicated Watch - getting the  dates right


06/11/2015 - 15:46

Instead of QP, we have a new term!  An interesting variation that places this watch in the modern age.  Does it require an adjustment in 400 years?  

So in seems the dude who commissioned this is probably an investment
06/12/2015 - 03:50

banker or hedge fund owner.  :-) But one with good taste. :-)

Re: So in seems the dude who commissioned this is probably an investment
06/13/2015 - 03:42

Based on the Moscow-based star chart comment earlier- it was a brilliant move if paid for up front in Rubles.

Re: The World's Most Complicated Watch - getting the dates right
06/13/2015 - 00:12

Marvellous Mars....

Very interesting so far, can't wait for more information!
06/14/2015 - 11:13

And pictures of course... wink

Just out of curiosity, does the ISO calendar get used by...
06/14/2015 - 23:33

...anyone? Or is it one of those things like Esperanto?


That apart, just wow!

I know that it is often used in Germany and Scandinavia
06/15/2015 - 09:53


Some of my clients use it
06/17/2015 - 05:02

They track their financial and accouting information by week, so they always refer to week #X.