Breguet contributes to the improvement of watchmaking principles, which he was already known for, and develops an abundance of innovations. His first major break-through is the creation of the self-winding watch, or perpetuelle. A short time later, he invents the gong-springs, creates its own aesthetic codes, which include the first engine-turned dials (guilloche), innovates with the terminal curve spring or Breguet balance spring, and launches the one hand subscription watch.
A calendar is described as perpetual when it automatically corrects itself to take account of long and short months, including 29 February in leap years.
Watches and clocks may display a more or less complete date, showing the day of the week, the day of the month and the name of the month. A calendar is described as perpetual when it automatically corrects itself to take account of long and short months, including 29 February in leap years.
The Republican calendar was introduced to replace the Gregorian calendar on 24 October 1793. In response, some watchmakers equipped their watches with conversion tables to the old Gregorian calendar.
