The 1815 TOURBILLON is designed for supreme precision. Unprecedented rate stability is assured by the one-minute tourbillon. The interaction between two patented mechanisms enables the watch to be set with great accuracy. When the crown is pulled, the balance inside the tourbillon cage stops instantaneously and the seconds hand jumps to the zero position. The watch can now conveniently be synchronised with a reference watch or a time signal.
More than 200 years ago, the invention of the tourbillon was the ingenious solution to a serious watchmaking problem. Because pocket watches were generally worn vertically, the influence of gravity on the balance often caused considerable rate deviations. To offset this unwanted effect, it was necessary to constantly change the orientation of the oscillation system. So the balance and the escapement were placed in a rotating cage, called tourbillon. This compensated position errors and increased rate accuracy. Since then, the tourbillon has lost none of its fascination. Its micromechanical complexity and artisanal finissage still symbolise engineering prowess and horological precision.
Unfortunately, it was long impossible to exactly set watches equipped with a tourbillon. This is because the tourbillon could not be stopped. In 2008, Lange’s calibre designers put an end to the impasse. At the time, they succeeded in braking the balance inside the rotating tourbillon cage directly and without delay. When the crown is pulled, a complex lever mechanism is activated which presses a movable V-shaped spring onto the balance wheel and stops the balance instantaneously. The new 1815 TOURBILLON is also endowed with this patented mechanism, which can partly be observed through the aperture in the dial. But this time, Lange’s product developers went a step further. They paired the stop mechanism with the also patented ZERO-RESET mechanism. It causes the blued-steel hand of the subsidiary seconds dial to instantly jump to the zero position when the crown is pulled, thus facilitating the synchronisation of the watch by positioning the minutes hand exactly above a minutes stroke and starting the watch with one-second accuracy.
The understated design of the 1815 TOURBILLON assures crisp legibility. It is therefore consistent with the underlying ideals of Ferdinand A. Lange, whose birth year graces the name of the timepiece. The tourbillon that is visible through the aperture in the dial is the only manifestation of the complexity of the watch. In comparison with earlier versions, its diameter was increased by nearly one millimetre to 13.2 millimetres. The arbor of the tourbillon carries the subsidiary second hand. In the interest of maximised contrast with the light-coloured dial, it is crafted from blued steel. The combination of Arabic numerals with the classic railway-track minute scale is reminiscent of historic A. Lange & Söhne pocket watches.
The hairspring and balance wheel are crafted in-house with extreme meticulousness and perfectly matched to one another. Precision also comes to the fore in the intricate finish of all movement parts and is crowned by the diamond endstone of the tourbillon. With a diameter of 39.5 millimetres, the case provides a harmoniously proportioned stage for the Lange manufacture calibre L102.1.