A. Lange & Söhne: Tourbograph Perpetual “Pour le Mérite”

In October 1994, A. Lange & Söhne presented the first collection of the new era, including the legendary TOURBILLON “Pour le Mérite”, the first wristwatch with a tourbillon and a fusée-and-chain transmission. It was followed in 2005 with a further model in which these two elaborate constructions were united: the TOURBOGRAPH “Pour le Mérite”. But there was more: a chronograph with the rattrapante function made it the manufactory’s most complicated watch at the time.

Now, the movement of the TOURBOGRAPH PERPETUAL «Pour le Mérite» has been endowed with a fifth complication, the perpetual calendar.

The TOURBOGRAPH PERPETUAL “Pour le Mérite” is the epitome of classic watchmaking: its hallmarks permeate all domains from design and engineering to consummate, flawless artisanship. The dial itself reflects the traditional approach in timekeeping. Arabic numerals, a railway-track minute scale, blued steel hands for the time and rhodiumed gold hands for the calendar as well as the cloverleaf arrangement of the subsidiary dials pay tribute to the famous A. Lange & Söhne pocket watches. Tradition also governs technical details such as column-wheel control for the chronograph and rattrapante mechanisms as well as the screw balance. Finally, it manifests itself in typical quality elements such as the two diamond endstones that suspend the tourbillon cage or the black-polished tourbillon bridge. The stately platinum case with a diameter of 43 millimetres is a fitting stage for this horological masterpiece.

Perpetual calendar

Of the 684 parts of the new L133.1 manufacture calibre, no fewer than 206 constitute the perpetual calendar with its analogue displays. It will correctly indicate the duration of each month until 2100. A one-time correction will be needed on the last day of February in this secular year. From then on, the calendar will again be correctly calibrated for the next hundred years. It has three subsidiary dials. The date at 12 o’clock and the day at 9 o’clock are indicated with rhodiumed gold hands. The month and leap year are both displayed at 3 o’clock. The upper half of the analogue date also accommodates the moon-phase display which is calculated to remain accurate for 122.6 years. Its deep-blue disc is made of solid gold.

Chronograph with rattrapante function

Apart from the two chronograph pushers on both sides of the crown, a third button at 10 o’clock reveals the split-seconds chronograph function. The fascinating function of the split-seconds mechanism can be observed in great detail with a look through the sapphire-crystal caseback. The precise control of the gold-plated chronograph hand and the blued rattrapante hand is handled by two column wheels. During a complete revolution of the 30-minute counter at 9 o’clock, as many lap times as needed can be stopped. The combination of a perpetual calendar with a split-seconds chronograph is very rare. Power management is an especially challenging undertaking. In particular, the simultaneous use of several functions calls for mechanical ingenuity, for instance when the calendar indications advance around midnight and the stopwatch function is used at the same time.

One-minute tourbillon

In the way they flawlessly interact, the tourbillon and the fusée-and-chain transmission offset two disruptive phenomena in a mechanical movement: gravity and waning spring force. Thus, they contribute to improved rate stability and rate accuracy. The L133.1 move- ment that works inside the TOURBOGRAPH PERPETUAL “Pour le Mérite” is already the tenth calibre with the delicately linked mechanism that overcomes the pull of gravity.

Fusée-and-chain transmission

The fusèe and chain transmission is the technical hallmark shared by all timepieces identified by the attribute “Pour le Mérite” in reference to the erstwhile Prussian order conferred for exceptional scientific merit. Via a fusée connected to the spring barrel with a chain, the force of the mainspring is delivered to the movement in constant increments thanks to the ingenious way in which the principle of levers is harnessed. A planetary gearing mechanism inside the fusée assures that the flow of power from the mainspring barrel to the escapement is not interrupted while the watch is being wound.

The TOURBOGRAPH PERPETUAL “Pour le Mérite” is being crafted in a limited edition of only 50 platinum-cased watches. The finish of the manufacture calibre complies with the highest standards of Saxon watchmaking artistry. Thermally blued screws, screwed gold chatons, bridges and plates made of untreated German silver and decorated with Glashütte ribbing and perlage as well as the hand-engraved chronograph bridge round out the highlights of the classic complication.