Date
The most common watch complication; and the most corrected
What it is
The date complication adds a 31-position disc to the movement, visible through a window in the dial. A 24-hour cam advances the disc one position at midnight. Because the disc has 31 positions for a calendar that includes months of 28, 29, 30, and 31 days, the owner must manually correct the date at the end of any month shorter than 31 days; five to seven times per year. Quickset date, which arrived in the 1970s, allows the crown to advance the date directly rather than requiring the hands to be run through midnight repeatedly.
History
Rolex introduced the first date wristwatch, the Datejust, in 1945. The date complication immediately became the most popular add-on to a basic three-hand movement. The cyclops magnifier; a small convex lens on the crystal above the date window; appeared on the Datejust in 1953 and remains a Rolex signature. Before quickset date became standard in the 1970s, correcting the date after a 30-day month required advancing the hands through midnight multiple times. The date window remains the most common complication in production today by an enormous margin.
How it works
A 24-hour cam (one rotation per day) presses a finger against the date driving wheel at midnight, advancing the date disc one position. The date disc sits behind a cutout in the dial, visible through the date window. Better movements use a stored-energy mechanism to produce an instantaneous jump at midnight rather than a slow advance over several minutes. The quickset mechanism lets the crown advance the date wheel directly in position two, bypassing the 24-hour cam.
Parts required
24-hour cam, date driving wheel, date disc (31 positions), date jumper spring, date corrector lever, quickset mechanism (on modern movements)
In the catalog
Related
- Annual calendar: Knows 30- vs. 31-day months; needs one correction per year
- Perpetual calendar: Programs every month length, including leap years, through 2100
