"I have invented a system to keep a watch on time and adjust it without anyone else having to do so. It requires a clock with a holder for the watch. The cost of adapting such a clock is one day's pay for a worker and as much again for the watch. (...) Each night on going to bed the watch must be set into the clock. The next morning, or one hour later, it will be exactly to time with the clock. There is no need even to open the watch. From the outside, nothing indicates where it has been touched." (Breguet in a letter to his son, June 1795).
The watch is placed in a cradle in the clock's cabinet, above the number 12. A rod enters the watch through a discreet opening in the bottom of its case. The clock drives this rod which sets the watch's minute hand to that of the clock.
Certain sympathique clocks also wind the watch.