A. Lange & Söhne presented the fourth model of the '25' collectionth Anniversary, the Lange 1 Tourbillon Perpetual Calendar, which integrates the perpetual calendar and tourbillon into the unmistakable Lange 1 design. On the occasion of its anniversary, A. Lange & Söhne presents the most complicated model in the collection in a limited edition of 25 in white gold with blackened steel hands. At the presentation of the first collection of the new era in October 1994, the innovative design of the Lange 1 aroused great admiration. Indeed, the unusual asymmetrical arrangement of the hour and minute indications in the compact space of the dial ensured a striking recognition. This arrangement was also retained in the Lange 1 Tourbillon Perpetual Calendar, which was presented for the first time in 2012. In order to integrate all the calendar indications into the architecture of the Lange 1's dial, the month display was arranged on an external circular counter. On its non-visible side, it is equipped with depressions differentiated according to the length of the months as well as a gear wheel that regulates its operation. All indications advance with a jump. The retrograde display of the day of the week replaces the power-reserve indicator, and the leap year is visible in a small window at 6 o'clock. The moon-phase display, precisely calculated for 122.6 years, includes a hand-engraved white gold moon disc visible through an aperture in the auxiliary small seconds dial. Thanks to the intuitive arrangement of the simultaneous advance calendar indications, the information is always perfectly legible. Lange 1 Tourbillon. The silver-plated dial of the "25" editionth Anniversary' discreetly integrates the blue colour through the thermally burnished steel hands and all other indications, including the Big Date numerals, to the alligator leather strap. The tourbillon, consisting of 69 individual elements with a patented stopping device, is visible only on the movement side. The finely crafted tourbillon cage rotates on its axis once a minute, thus compensating for the influence of gravity on the eccentric balance developed by Lange. The patented seconds stop mechanism allows the balance wheel to be locked in the tourbillon cage at any time by pulling out the crown to set the watch to the exact second. The tourbillon bridge bears an engraving in blue depicting the Lange Great Date with the number 25. The number 25 not only refers to the anniversary, but also to a particular detail of the first presentation that took place on 24 October 1994; on that occasion, the date indications on the watches presented were adjusted to the 25th in order to appear correctly in the press the following day. The effective winding of the automatic calibre L082.1 is ensured by a central rotor with an oscillating weight, with the central segment in 21-carat gold bearing the inscription A. Lange & Söhne, and the outer rim of the rotor in platinum. Typical Lange quality features of the 624-component movement include the black polishing of the upper part of the cage and a diamond pivot cover that anchors the tourbillon.
