A. Lange & Söhne: Datograph Perpetual Tourbillon

A. Lange & Söhne presents Datograph Perpetuo Tourbillon, the latest masterpiece from Saxony pairs three complications with five supplementary functions with a clear and harmonious design.

The black solid-silver dial of the new model contrasts beautifully against the 41.5- millimetre platinum case as well as the hands and hour markers in rhodiumed gold. It is limited to 100 watches.

DATOGRAPH

DATOGRAPH designates a column-wheel chronograph with a precisely jumping minute counter, a flyback function and the typical Lange outsize date. To master the challenge of precise short time measurements, the product developers relied on an ingenious feature that had already proven itself in the DATOGRAPH UP/DOWN. It distils three major technical advances in chronograph design into one: the column-wheel mechanism assures that all chronograph functions are reliably controlled. The jumping minute counter crisply displays the stopped times. And the flyback function allows the duration of consecutive events to be measured with extremely short reaction times.

PERPETUAL

PERPETUAL, the middle element of the name, refers to a instantaneously jumping perpetual calendar with a moon-phase display. All indications of the perpetual calendar – including the outsize date as well as the day-of-week, month and leap-year displays in subsidiary dials – switch instantaneously and thus provide unambiguous readings at all times. A first correction of the mechanism by one day can wait until the first day of March in the secular year 2100. And because of its stunning mechanical precision, the moon- phase display will only deviate from the true lunation by a single day after 122.6 years. Three correctors allow the separate adjustment of the moon-phase display, the day of the week and the combined advance of the month and leap-year indications. After a standstill of merely a few days, the rapid-correction pusher at ten o’clock can be used to conveniently update all displays at the same time.

TOURBILLON

The fascinating tourbillon mechanism is exposed by the sapphire-crystal caseback and the open tourbillon bridge. There, the escapement rotates about its own axis once a minute inside the filigreed cage. This rotary motion offsets the influence of gravity on the balance wheel with eccentric poising weights. In conjunction with the free-sprung balance spring crafted in-house, it assures excellent rate accuracy across the entire 50- hour power reserve. The power-reserve indicator integrated at the end of the tachymeter scale reminds the owner when it is time to rewind the watch. For the first time in a Lange tourbillon, the balance beats at a rate of 18,000 instead of the conventional 21,600 semi- oscillations per hour. This corresponds to a frequency of 2.5hertz. Consequently, stopped times can be displayed with an accuracy of one-fifth of a second. The patented stop-seconds mechanism instantaneously brings the balance wheel inside the tourbillon cage to a standstill when the crown is pulled. This allows the watch to be set with one- second accuracy.