SIHH 2014: A. Lange Richard Lange Perpetual Calendar “Terraluna”

Regulator with orbital moon-phase display and 14-day movement…

A. Lange Richard Lange Perpeutal Calendar Terraluna Duo

Introducing the Richard Lange Perpetual Calendar “Terraluna”, a horological masterpiece from A. Lange & Söhne.  The Terraluna features an orbital moon-phase display, a perpetual calendar with the Lange outsize date, a power-reserve of 14 days, and a constant-force escapement.    The watch will be offered in pink gold (Ref 180.032) and white gold (Ref 180.026), non limited though of course a watch of this nature will be definition be very exclusive.  On the back, the patent-pending orbital moon-phase display shows the location of the moon relative to the earth and the sun – for the first time ever in a wristwatch.  Further Lange-style quality hallmarks include the hand-engraved balance cock and a lavishly hand-decorated movement.

On the dial side of the 45.5-millimetre pink- or white-gold case, the watch utilizes a regulator layout with Lange’s typical interlocking circles/subdials, and apertures for the pepetual calendar displays.  The large minute circle is at the top of the dial.  The smaller dials for the hours and seconds are beneath it on the right and left.  As was already the case with the Richard Lange Tourbillon “Pour le Mérite” presented in 2011, this dial design was inspired by a great historic role model: Johann Heinrich Seyffert’s 1807 regulator from the world-famous timepiece collection of the Mathematics and Physics Salon.

A. Lange Richard Lange Perpetual Calendar “Terraluna”

45.5mm x 16.5mm white or pink gold case, Solid silver argenté dial, manual wind Lange Cal 096.1 (details below)

Richard Lange Perpetual Calendar Terraluna White Gold

Time indicated in hours, minutes, and seconds; perpetual calendar with outsize date, day of week, month, and leap year; power-reserve indicator; orbital moon-phase display with day/night indication on the movement side

Richard Lange Perpetual Calendar Terraluna White Gold Beauty Shot

Crown for winding the watch and setting the time; push piece for advancing all calendar displays; recessed push pieces for separate correction of month, day of week, and moon phase

Richard Lange Perpetual Calendar Terraluna Gold

All displays of the calendar switch forward instantaneously to assure unambiguous readings at all times. To keep the power for the switching process as low as possible, the required energy is gradually built up via a cam and then released abruptly at midnight.  The leap-year indication is located on the right-hand side of the 15 of the minute circle:

Richard Lange Perpetual Calendar Terraluna White Gold Detail

Richard Lange Perpetual Calendar Terraluna White Gold Pusher Detail

Show below is the slit aperture is the power reserve indicator — maximum of 14 days, fully wound

Richard Lange Perpetual Calendar Terraluna Power Reserve Aperture

The Terraluna is equally impressive on the back side.  The movement side presents an innovative and useful orbital moon-phase display that depicts the constellation of the earth, moon, and sun.

A Lange Richard Lange Perpetual Calendar Terraluna Caseback

Upper (L-R) new moon, waxing moon, Lower (L-R) full moon, waning moon

Lange L096.1 Moon Orbits Illustration

The display consists of three discs. On the star-studded celestial disc, the moon – visible through a round aperture – orbits around the earth anti-clockwise once a month. The mechanism reproduces the synodic month of 29 days, 12 hours, 44 minutes, and 3 seconds so precisely that it takes 1058 years before the display needs to be corrected by one day. Beneath it, the lunar disc rotates, featuring two round new moons. The progression of the moon phases can be observed through the aperture in the celestial disc. In the constellation view, the position of the sun is occupied by the balance. On new-moon days, the dark moon stands between the earth and the sun. It appears as a bright sphere on the opposite side of the earth on full-moon days. Thus, the position and phase of the moon are indicated simultaneously. In the centre of the display, the earth rotates about its own axis once a day. It is daytime on the half that faces the sun, or the balance, and night-time on the other. The peripheral 24-hour scale provides a time-of-day reference for the northern hemisphere.

Lange manufacture calibre L096.1

manually wound; 787 parts; 14 day power reserve

crafted to the most exacting Lange quality standards, decorated and assembled by hand; precision-adjusted in five positions; twin mainspring barrel; constant-force escapement with remontoir spring produced in-house; three-quarter plate made of untreated German silver; balance cock engraved by hand; lever escapement; 21,600 bph

A Lange Caliber L096.1 Front and back

A Lange Caliber L096.1

To achieve a vivid and aesthetically sophisticated image of the orbiting moon-phase display, Lange chose a special coating process.  On the celestial disc, for example, interference effects absorb all of the non-blue colour spectra of the incident light. The result is a deep-blue surface studded with more than a thousand high-contrast, sharply contoured stars.

A Lange Caliber L096.1 Detail

With two rugged mainsprings, the twin barrel delivers a power reserve of 14 days. When a spring barrel stores so much energy, special technical precautions must be taken to keep the rate of the watch stable during the entire power-reserve period. The torque of the fully wound spring would be too high to be delivered directly to the going train. And as its torque declines when it approaches the unwound state, the accuracy of the watch would deteriorate. An elaborate constant-force escapement compensates for both phe-nomena. In ten-second intervals, it releases an identical portion of the available energy to the balance, thus assuring that the torque remains constant. The result is an unvarying amplitude and high rate accuracy from the first day to the last. At the 6-o’clock position, a power-reserve indicator in the form of a circumferential ring tells the owner when the time has come to replenish the movement with fresh energy via the winding crown.

The Richard Lange Perpetual Calendar Terraluna is priced in white gold at $216,400 and in pink gold for $215,100. Visit A. Lange & Söhne for more.