The crown is the main control on a mechanical watch, used to wind the mainspring and to set the time. On a wristwatch with an analogue display, it is the little knob for adjusting the time.
How does a crown work?
In its normal position, the crown winds the mainspring when it is turned. Pulling it outward switches the mechanism from winding to setting, so the same knob can then be used to move the hands. On many watches the crown also has a first pulled-out position, and turning it there changes the date.
What is a screw-down crown?
Crowns come in two kinds. A push-in crown does not lock. A screw-down crown screws down and locks in place. That lock lets the watch resist greater pressure, giving water resistance of 20 atm or more. A push-in crown offers no such lock. Some watches have several crowns rather than just one.
Where is the crown on a watch?
The crown is nearly always placed on the right side of a wristwatch. So on most wristwatches, the wearer reaches for the right-hand side to wind or set it. Bullhead watches put the crown and the chronograph pushers at the top of the case. Wherever it sits, the crown keeps the same two jobs: winding and setting.
Where it comes from
Old pocket watches were wound with a separate key. With a crown, no separate key was needed. Jean-Adrien Philippe showed his crown winding and setting system in 1842 and patented it in 1845. In 1844 Adolphe Nicole took out a London patent for a keyless winding system that became widely used.
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