The perpetual calendar is one of the masterpieces of haute horlogerie, as this long-term genius knows the correct length of months even in leap years. Only in 2100, when, according to the Gregorian calendar, the leap year is omitted, does the complex mechanism require manual correction. However, the challenge lies not only in the mechanical “programming” but also in presenting the numerous calendar-related information in a clear and concise manner within the limited surface of the dial.

One of the most beautiful examples of the genre was achieved by A. Lange & Söhne with the Lange 1 Perpetual Calendar, first presented in 2021. In order to preserve the signature design of the Lange 1 watch family with its off-center and non-overlapping displays, Lange?s watchmakers opted for a completely new approach and developed a peripheral month ring that advances instantaneously at the end of each month. Premiered in 2012 with the launch of the Lange 1 Tourbillon Perpetual Calendar, this innovative mechanism replaces the traditional design where the month display is controlled by a 48-step cam. 
?The commitment to tailor the complex mechanical requirements to the characteristic design of the Lange 1 presented our developers with constructive challenges, as the large peripheral ring has to be advanced instantaneously by 30 degrees from one month to the next. Throughout the month, energy is collected via a cam in order to provide the required power exa...