A. Lange & Söhne Datograph Perpetual

With an ingenious combination of a flyback chronograph and a perpetual calendar, the master watchmakers at Lange have yet again substantiated their horological artistry.

Capturing not only the moments but also short and long eternities is a challenge that “A. Lange & Söhne” has successfully mastered on many occasions. Chronographs such as the DATOGRAPH and the LANGE DOUBLE SPLIT consummately measure even the shortest moments, but with the LANGEMATIK PERPETUAL, the eminent Saxon manufactory proved that it also masters “perpetuity”. Its perpetual calendar mechanism requires no correction until 2100, a secular year according to the Gregorian calendar. Thus, on 28 February 2100, all displays can be collectively advanced by one day to skip the 29th with pushbutton ease.

The DATOGRAPH PERPETUAL integrates the most salient innovations of both watch types into one truly spectacular timepiece. And for the second time, the Lange outsize date is transformed into a “perpetual outsize date”, overcoming the idiosyncrasies of the Gregorian calendar with its newly developed perpetual calendar mechanism.

In other words, the DATOGRAPH PERPETUAL always indicates the correct date, including leap years. Apart from the day of the week, the month, the four-year cycle with leap years, and the moon phase, the new Lange watch also indicates the day/night rhythm. Because of the extreme precision of the mechanism, the moon phase deviates from the true lunar cycle by only one day every 122 years.

But the DATOGRAPH PERPETUAL does not only excel in measuring long periods of time. It is also a specialist in short-time measurements that showcase the useful functions of the legendary Lange flyback chronographs with the precisely jumping minute counter and the classic column wheel mechanism. It is capable of measuring “the moment of infinite worth” mentioned above to an accuracy of one-fifth of a second.

The complex movement of the DATOGRAPH PERPETUAL consists of 556 parts, most of which are meticulously finished by hand. It enriches the range of Lange watches with significant complications and at the same time reaffirms the manufactory’s long-standing tradition in crafting both perfectly simple and extremely complicated masterpieces.

As is the case with all Lange watches, the DATOGRAPH PERPETUAL features a sapphire-crystal back which reveals the beauty of the exclusive manually wound calibre L952.1 movement with its plates and bridges made of untreated German silver. The back also exposes those minuscule, rate-critical parts that only very few manufactories can produce in-house – such as the balance spring.

The DATOGRAPH PERPETUAL is fitted with a newly developed balance spring optimised for this type of watch and manufactured entirely by Lange. The glucydur balance with eccentric poising weights was also developed by Lange.

These two elements are responsible for the superb rate stability of the escapement that beats with a frequency of 2.5 hertz, corresponding to 18,000 semi-oscillations per hour. Additionally, a special spring barrel stopwork assures that the mainspring delivers power only in those tension states with approximately constant torque. This, too, perceptibly enhances the rate accuracy of the DATOGRAPH PERPETUAL.

Lange’s calibre designers have developed a new advancing mechanism for the perpetual calendar. It requires only one switching pawl thanks to the use of toothing of different lengths and a specially shaped calendar ratchet wheel cover.

This configuration, for which a patent application was filed in March 2005, shortens the switching path involved in manual calendar adjustments and thus reduces the power required to advance the outsize date. Overall, the complex calendar mechanism consists of 233 parts that add only 1.9 millimetres to the total 13.5-millimetre height of the watch. It is completely autonomous until February 2100, the year in which the Gregorian calendar skips February 29. After that, the next manual intervention is needed in the year 2200.

The calendar indications cannot only be corrected individually with recessed push pieces; the DATOGRAPH PERPETUAL also has a convenient universal corrector that allows all calendar displays, including the date, to be collectively advanced in steps of one day. To prevent this from happening inadvertently, the crown must be pulled first, for example in the event that the watch has stood still for some time.

This new, exceptional watch from Lange – each one takes several months to manufacture and assemble – also manifests its class visually with a stately platinum or pink gold case. With a diameter of 41 millimetres, it ranks among the larger Lange timepieces. The solid-silver dial with rhodiumed-gold appliques is understated and easily legible. With their Superluminova coating, the hands glow subtly in the dark.

Technical details
Movement
Lange manufacture calibre L952.1, manually wound, crafted to the highest Lange quality standards and largely assembled and finished by hand; precision-adjusted in five positions; plates and bridges made of untreated German silver; balance cock engraved by hand
Number of parts: 556
Jewels: 45
Screwed gold chatons: 4
Escapement: Lever escapement
Balance: Shock-proofed glucydur balance with eccentric poising weights; superior-quality balance spring produced in-house, with patent-pending attachment design (balance spring clamp),frequency 18,000 semi-oscillations per hour, precision beat adjustment with lateral setscrew and whiplash spring
Power reserve: 36 hours when fully wound

Functions
Flyback chronograph with precisely jumping minute counter; perpetual calendar with outsize date, moon-phase display, day-of-week, month, four year/leap year, and day/night indication, hours, minutes, small seconds with stop seconds, tachometer scale

Operating elements
Crown for winding the watch anand setting the time, two push pieces for operating the chronograph, a universal corrector for simultaneously advancing all calendar displays plus one recessed push piece each for the day of the week, the month, and the moon phase.

Reference no. 410.032
Case: Ø 41.0 mm, pink gold.
Dial: Solid silver, argenté. Hour markers luminous.
Hands: Pink gold and blued steel. Hour and minute hands luminous.
Glas and Caseback: Sapphire crystal glass.
Strap: Hand-stitched crocodile strap buckle in pink gold.

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