Laurent Picciotto, Chronopassion and the Hydro Mechanical Horologists (HYT) Ion Schiau, Xavier Casals and Vincent Perriard.
© Stéphane de Bourgies.
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It is perpetual because it automatically takes into account months with 30 days and the 28 or 29 days in February. It therefore incorporates a mechanical memory whose sequences are repeated every 48 months to correspond to the cycle of leap years.