Date is a complication that shows the day of the month on a watch. NOMOS calls it a small complication, popular on mechanical watches for both men and women. Today it most often appears through a window in the dial, usually at 3 or 6 o’clock.
How does a date complication work?
Most date displays use a fairly simple wheel system. A disc under the dial carries the numbers 1 to 31. In NOMOS’s explanation, a train of gears links the minute wheel at the centre of the movement to this date disc. As the hours pass, the gears turn with the rest of the movement. At midnight the disc jumps forward, and the next numeral moves into place in the window.
Does a date need to be set by hand?
A simple date counts to 31 every month. It cannot tell that some months are shorter. In months with fewer than 31 days, the owner has to move it on by hand. Annual and perpetual calendar mechanisms are different. They account for the length of the month themselves. The calendar date and the quickset date both appear among the common complications. The date complication is found on watches from Omega, Longines and Tissot.
How else can the date be shown?
A window is not the only option. The date can also be shown by a hand that points to numbers printed on the dial. Before the date window became common, calendar watches often worked this way. The numbers ran around the edge of the dial, and a hand mounted at the centre picked out the day.
Where it comes from
The familiar date window at 3 o’clock comes from the Rolex Datejust, launched in 1945. It is described as the first self-winding chronometer wristwatch to show the date through a window in the dial. A window shows a single numeral at a time, printed on the disc beneath the dial. The 3 o’clock position remains one of the two usual places for it, with 6 o’clock the other.
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