The Excalibur Bi-Retrograde Calendar by Roger Dubuis

This year, Roger Dubuis celebrates its 30th anniversary, and for the occasion, the company pays tribute to its co-founder’s favourite complication: the bi-retrograde display.

This function, previously featured in the Excalibur Grande Complication alongside a dozen other highly complex mechanisms, takes centre stage once again. The Maison has also introduced a less complicated, more classic edition to further honour the bi-retrograde display.

Also referred to as “the ecliptic counters” by the Maison a nod to their elliptical shape and distinctive role in indicating the months and date the design showcases a symmetrical dial layout. Enhanced by refined detailing, it pays homage to the Maison’s early creations from 1996.

Glossary

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Glossary
The differential

The differential

The differential is a gear system, which is mainly found in watches with more than one escapement, such as double balance wheels or double tourbillons. Its main function is to provide an average between two different rates of timekeeping. It helps ensure accurate timekeeping in watches that have more than one escapement by averaging the rates of the different escapement wheels, which ultimately contributes to the watch's overall accuracy and functionality.

The differential is constructed using conical gears that connect the two shafts, facilitating the transfer of energy from the faster side to speed up the slower one while maintaining an overall energy balance. This mechanism was originally invented in the 1830s by a French engineer.