Centred exclusively on its eponymous complication, the LANGE 1 PERPETUAL CALENDAR introduced two years ago, represents the highest standards in precision, design and originality, resulting in a singular appeal. The new model version, housed in a 950-platinum case and measuring 41.9 mm in diameter, is complemented with a black dial, thus enriching the watch family with a particularly refined colour combination. The month ring provides the framework for all the displays. The numerals of the outsize date and the leap year contrast well against the black background. All calendar indications switch instantaneously and therefore produce unambiguous readings at any given time. They can be advanced collectively or separately with correctors. Once set correctly, the mechanism is programmed to accurately display the turn of the month until 2100. 

A perpetual calendar watch the Lange way 

Designing a mechanism for a perpetual calendar that takes into account the different durations of the months in a year as well as the leap years, presents a challenge that the ambitious A. Lange & Söhne developers took on in 2001 with the LANGEMATIK PERPETUAL. Their objectives: seeking innovative technical solutions while assuring optimum legibility. In order to preserve the signature design of the LANGE 1 watch family with its off-centre and non-overlapping displays, Langeʼs 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, the innovative mechanism replaces the traditional design where the month display is controlled by a 48-step cam.  

Balanced design and function 

“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 exactly on time, at midnight on the last day of the month,” explains Anthony de Haas, Director of Product Development. “Thanks to this design feature in the LANGE 1 PERPETUAL CALENDAR, the watch familyʼs distinctive face is maintained. The timepiece is therefore also emblematic of our philosophy to continuously break new ground in the realm of precision watchmaking.” 

Precise moon phase 

Adding a day/night indicator to the moon-phase display is also typical of the manufactureʼs continued quest for precision. Constructed across two levels, it consists of a solid-gold celestial disc with graduated blue hues that rotates around its own axis once during 24 hours. Against this backdrop, the white-gold moon performs its synodic orbit in 29 days, 12 hours, 44 minutes and 3 seconds ‒ with such precision that the display only needs to be corrected by one day after 122.6 years. First implemented in the LANGE 1 MOON PHASE in 2016, the indication depicts the earth’s companion moving across a bright-blue sky during the day and a dark-blue starry sky at night, thus indicating the diurnal and nocturnal hours respectively.  

The high standards of artisanal perfection upheld by the Saxon manufacture immediately become apparent at a glance through the sapphire-crystal caseback of calibre L021.3 ‒ it is elaborately finished by hand and assembled twice. The technical features of the manufacture movement include a unidirectional winding rotor in 21-carat gold with a centrifugal mass in 950 platinum, a power reserve of 50 hours and a balance with eccentric poising weights that beats at a frequency of 21,600 semi-oscillations per hour. Lange-typical quality hallmarks such as plates and bridges made of untreated German silver decorated with Glashütte ribbing, five gold chatons held by blued-steel screws as well as the balance cock engraved free-hand, with the whiplash spring mounted above to regulate beat adjustments reflect the manufactureʼs lofty aspirations in every single detail. 

With its launch in 2013, the 1815 RATTRAPANTE PERPETUAL CALENDAR marked a milestone in A. Lange & Söhne’s more recent history: no less than seven chronograph calibres had previously been crafted by the Saxon manufactory. Equipped with a specially developed movement, it united three of the most elaborate complications – very rare in this configuration – while maintaining the classic, elegant design of the 1815 watch family. The outstanding timepiece excels in the measurement of short and long distances: thanks to its eponymous complications, the 1815 RATTRAPANTE PERPETUAL CALENDAR sets standards in both short-time measurement and the display of calendar periods.

Comparative time measurements to a fraction of a second

The rattrapante function of the 1815 RATTRAPANTE PERPETUAL CALENDAR represents one of the greatest horological challenges. In addition to the conventional functions of a chronograph, this sophisticated complication is capable of measuring intermediate times and comparative times as well as determining minimum and maximum values in the course of one minute. Since the balance wheel of the manufacture calibre L101.1 beats with six semi-oscillations per second, the stopped times can be recorded with an accuracy of one sixth of a second. High-precision readings are assured thanks to the additional graduation on the peripheral minute scale. The precisely orchestrated proceedings within the movement can be observed through the sapphire-crystal caseback. The classic two-column wheel transmission is used to control the measurement of stopped and intermediate times. As is typical for A. Lange & Söhne, technical intricacy is coupled with a high degree of artisanship. The upper surfaces of all moving parts are decorated with straight graining while the peripheral chamfers are polished. Only an experienced finisseur has the skill to polish the bevels to sharp and flat perfection.

A calendar for perpetuity

While the rattrapante chronograph is capable of measuring different time intervals to a fraction of a second, the remarkable technical feat of the perpetual calendar lies in its “long-term memory”. As its name suggests, the complex and prescient mechanism ensures that the date, day of the week and month are correctly displayed ‒ every single day, during decades, even taking leap years into account. The calendar indications must only be corrected by one day but not until 1 March 2100; according to the rules of the Gregorian calendar, the leap year will then be skipped.

The high-precision moon-phase display has also been programmed with the long term in mind. It so closely emulates the duration of the synodic orbit of the earth’s satellite that it would take 122.6 years for the display to be corrected by one day.

Harmoniously arranged displays

Not only the technical details distinguish the 1815 RATTRAPANTE PERPETUAL CALENDAR but also the well-organised arrangement of its displays. Following the DATOGRAPH PERPETUAL TOURBILLON (2019) and the LANGE 1 PERPETUAL CALENDAR (2021), it is the third A. Lange & Söhne timepiece showcasing an 18-carat pink gold dial: the warm, golden hue contrasts elegantly with the cool white gold of the case. With a traditional railway-track minute scale, Arabic numerals and the harmonious arrangement of the four subsidiary dials, the dial embodies the essence of the watch family named after the birth year of Ferdinand Adolph Lange.

The manifold displays of the perpetual calendar and the rattrapante chronograph echo the classic aesthetics of earlier Lange pocket watches. The two pairs of combined calendar indications are arranged at 3 and 9 o’clock. The left subsidiary dial shows the date and day of the week, the right the month and leap year. Sharing an auxiliary dial with the subsidiary seconds at 6 o’clock, the moon-phase display provides an expressive colourful accent. The minute counter and power-reserve indicator are located at 12 o’clock. The shorter gold hand in the inner circle reveals when it is time to deliver new power to the movement via the winding crown. The longer hand made of blued steel imparts information about the stopped minutes.

Manufacture calibre L101.1

Incorporating traditional design and engineering features, the manually wound movement L101.1 totals an impressive number of 631 individual parts. The mechanism of the perpetual calendar alone requires 211 components, a further 206 account for the rattrapante-chronograph mechanism. A screw balance, which is driven by the balance spring developed and manufactured in-house, ensures high rate stability. Lange-typical quality hallmarks such as screwed gold chatons, blued screws, an elaborate whiplash precision index adjuster and the hand-engraved balance cock are visible through the sapphire-crystal caseback. The finissage of the movement, which is assembled twice, reflects A. Lange & Söhne’s high standards in every single detail.

 “With three classic complications, the manufacture calibre L101.1 is one of our most complex movements. Each one in itself already constitutes a technical feat; when combined, they represent a far greater challenge. For our designers and our watchmakers in equal measure, since the tweaking and tuning process of all mechanisms requires an exceptionally high degree of dexterity and technical expertise,” explains Anthony de Haas, Director of Product Development at A. Lange & Söhne.

Three versions

The dimensions of the new 1815 RATTRAPANTE PERPETUAL CALENDAR remain unchanged: the case boasts a diameter of 41.9 millimetres and a height of 14.7 millimetres. In addition to the new 1815 RATTRAPANTE PERPETUAL CALENDAR in white gold with a pink-gold dial limited to 100 pieces, the model also comes in a platinum/argenté and pink- gold/argenté case/dial combination.