When we are talking about truly iconic watches then the Da Vinci is surely one to be considered as such. Introduced in 1985. as model reference 3750, Da Vinci was the world's first automatic chronograph to feature a perpetual calendar, year display and perpetual moon phase display!
With an unparalleled level of calendar complication, it is still a miracle of mechanical watchmaking. It's mechanical calendar will function properly WITHOUT ANY EXTERNAL ADJUSTMENT until March 1, 2100 when the normally expected leap year will be skipped!
Unlike other perpetual calendars, the 3750's calendar is manually set (forwarded) just by the crown - there are no external push 'holes' for the separate adjustment of day/date/month/year and moon phase. It's all done automatically by a simple turn of the winding crown. Of course, that means that the calendar cannot be 'set back' to the previous day but this is really not required since the Da Vinci can 'tell' all of the above by itself anyway!
This watch encompasses one of the most extreme reduction gear ratios in the history of watchmaking: 1 : 6,315,840,000 turns of escape wheel are required to move the 100-year display for just 1.2 mm. At the same time, the balance wheel would make 95 billion ticks and tocks!
To say that IWC was excited about Da Vinci would be understatement. Here is the quote from watch booklet which captures the excitement of the new model:
"With the Da Vinci we also present to you a brand new century slide for the year 2200 - 2499. And that in a sealed glass tube. Keep it in a good place for the next 200 years. At the beginning of January 2200, take it to your watchmaker. He will exchange the slide in next to no time and your Da Vinci is ready again to show the time for the next 300 years.
Perhaps the visit at your watchmaker's will last a little longer than expected. Not to worry. He will seize this opportunity to take a close look at the watch movement ad calendar. On looking, he will certainly be astounded that such a thing was ever able to be produced. And that 215 years ago."
Needless to say, there are only a handful of watchmakers trained to assemble the Da Vinci. The entire calendar is located between the dial and movement plates, and held by just 4 screws. Not only that each gear, lever, tension spring and bridge must be placed in exact order but the each tooth of each wheel can be set in only one exact position.
Knowing your limits and sticking to them is one rule I religiously adhere to - so when the new baby arrived on Friday, I was just happy to take it out of the case, check the overall condition of the movement, made minor adjustments to the tome keeping, advanced the calendar for a few days to make sure it works as it should - and to take a couple of photos of the dial for my blog.
I am just so glad I won't be around in January 2200. to help you with the calendar slider!