Simple (Date) Calendar

Definition

A calendar mechanism showing the date (and often day and/or month) which requires manual correction at the end of short months, because it does not account for months of fewer than 31 days.

Historical origin

Date indications appear on watches from the seventeenth century onward; the mass-produced, quick-set date wheel became a mainstream feature of wristwatches from the mid-twentieth century.

How it works

Pocket watch context

Date-only or date-and-day calendar pocket watches were produced from the eighteenth century, often combined with moon phase in a single calendar dial layout.

Wristwatch context

Extremely common in modern mechanical and quartz wristwatches, frequently paired with a day indication in a 'day-date' layout.

Clock context

Date calendar clocks, particularly French and American mantel and wall clocks from the nineteenth century, use an equivalent disc-and-jumper mechanism driven from the clock's own 24-hour motion work.

Identification

• Date aperture or subsidiary date hand requiring manual advance after months of fewer than 31 days
• Quick-set corrector (recessed pusher or crown position) present on many but not all examples
• Midnight date change that may 'creep' over several hours on lower-grade or worn examples rather than jumping instantaneously

Servicing notes

Date-change timing and crown-position correction are common sources of user-induced damage (changing the date in the disallowed 'danger zone' around midnight can bend the jumper); repairs to the change mechanism should go to a watchmaker.

General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.