Perpetual Moon 41.5 platinum "celestial blue"
- Limited edition
- 30 meters water resistance
- 41.5 mm case
- Alligator leather strap
The cold shimmer of a starry night. The diaphanous presence of a large mother-of-pearl moon. The pale gleam of platinum. Perpetual Moon 41.5 Platinum “celestial blue” is expanding the collection’s different variations on the largest astronomical moon. Every part of this piece evokes the radiance of the night, from the dial stamped with the House’s “Stellar Rays” decor to the moon disc in a grained sky and the navy-blue alligator-leather strap.
Arnold & Son continues to explore the theme of moon phases with a constant eye for detail and decoration. After revisiting the design of the Perpetual Moon, this celestial-blue version is joining the collection. As always, in the backdrop, the moon-phase complication is accentuated to striking effect. In a platinum case measuring 41.5 mm in diameter and 11.30 mm thick, Perpetual Moon 41.5 Platinum “celestial blue” presents the largest of all moons.
This edition showcases the latest characteristics of the Perpetual Moon collection, substantially redesigned to achieve greater refinement and subtlety. The lugs have been simplified and refined. Instead of their original cross shape, they now present a tauter form of plunging bars with bevelled ends. They form a single piece with the case middle, in terms of both their construction and appearance. After remaining at 42 mm for a long time, the case has been slightly reduced to 41.5 mm without altering the dial opening, giving a slimmer bezel instead. As a result, the eye is drawn in towards the dial, its finishes, its immense moon and its dominant pale-blue shade.
The dial is adorned with the “Stellar Rays” finish. Its aesthetic is obtained through skilfully irregular engraving. Various depths and widths of rays are successively combined to create a specific rhythm. Their sequence produces a fluctuating play of light, which is accentuated by the depth created by several layers of transparent lacquer.
The large white mother-of-pearl moon is realistically rendered with hand-painted shadows and coated with Super-LumiNova. It is placed on a grained sky featuring a midnight-blue PVD treatment. Following the tradition of the Perpetual Moon collection, it is surrounded by the Big Dipper and Cassiopeia constellations, which are also hand-painted and coated with luminescent material.
The constellations have been chosen as a reference to John Arnold’s history as a maker of naval chronometers. The Big Dipper and Cassiopeia have been used as points of reference since time immemorial. Midway between these easily identifiable constellations is the North Star. Its position inevitably defines the North and its angular altitude, or position in the North-South plane, and allows the distance to the equator, i.e. the latitude, to be estimated. Before instruments for measuring longitude were invented, it was the most reliable way to determine the position of a boat in the middle of the ocean.
On the case back, a secondary indicator allows the moon phase to be adjusted quickly and precisely. The hand-wound calibre that powers it, reference A&S1512, is capable of tracking the development of its segments with exceptional precision. The duration of a complete lunar cycle is 29 days, 12 hours, 44 minutes and 2.8 seconds. Arnold & Son has succeeded in representing it in such a way that it would take 122 years for this movement, if regularly wound, to accumulate a day’s difference between its display and celestial reality.
Like all Arnold & Son movements, the A&S1512 calibre has been entirely developed, manufactured, decorated, assembled, adjusted and cased at the Manufacture in La Chaux-de-Fonds. The calibre features two barrels and an oscillating frequency of 3 Hz, providing a power reserve of 90 hours.
- hours, minutes, astronomical moon phases, second moon-phase indicator on the back
Calibre: A&S1512, mechanical with manual winding
Diameter: 34 mm
Thickness: 5.35 mm
Power reserve: 90 hours
Frequency: 3 Hz / 21,600 vph
mainplate: rhodium-plated, Côtes de Genève stripes radiating from the centre
bridges: polished and chamfered
wheels: circular satin-finished
screws: blued and chamfered, polished heads
second moon-phase indicator: rhodium-plated and circular-grained
- ‘Stellar Rays’ decor, with celestial-blue PVD treatment
- sky: grained, with midnight-blue PVD treatment
- constellations: hand-painted, with added Super-LumiNova
- moon: mother-of-pearl disc coated with Super-LumiNova, hand-painted details
Material: Platinum (Pt 950)
Diameter: 41.5 mm
Thickness: 11.30 mm
Crystal: domed sapphire, with an anti-reflective coating on both sides
Case back: sapphire crystal, with an anti-reflecting coating
- Water-resistance: 30 m / 3 ATM
Materials: blue alligator leather, hand-stitched
- Buckle: pin buckle, 18-carat white gold
Limited Edition: 38 timepieces
As a contemporary Swiss watch brand, Arnold & Son continuously reinvents its approach to pay homage to the work of John Arnold, a man who provided solutions to the challenges of his era, notably the accuracy and reliability of timepieces. As a renowned watchmaker, he produced some of the most accurate marine chronometers of the 18th century and won several awards from the Bureau des Longitudes, spurring him on in his research into timekeeping. As an inventor, he filed a number of patents, including one for a compensation balance featuring a bimetallic balance-spiral (1775) and another for a helical balance spring with terminal curves (1782). He also produced simplified chronometer design principles that permitted mass production of these timepieces, a number of which were made available to His Majesty’s Royal Navy, making John Arnold one of its principal suppliers. One of his least known but most significant contributions was the modern definition of the term ‘chronometer’, which today refers to a high-precision timepiece driven by a movement that has passed an accuracy inspection carried out by an official neutral body.
A Fine Watchmaking House stands out for its mastery of the classics. Arnold & Son has based its identity on its ability to produce fine watchmaking complications that are linked to the heritage of John Arnold. These include true seconds (or dead-beat seconds) – a function recalling the escapements of pendulum clocks marking out the seconds – and dual time zones driven by twin regulating organs, which hark back to the original method of maritime positioning. The moon-phase displays also illustrate the brand’s mastery of the classics, while revealing a more unconventional side through the use of large moons in sculpted gold. Lastly, the power reserves of up to eight days offered by Arnold & Son pay homage to marine chronometers, which also benefited from an impressive autonomy.
The twenty or so calibres presented to date by Arnold & Son have all been conceived, designed, developed, machined, decorated, assembled and adjusted by its sister Manufacture, La Joux-Perret. This independence and creativity demonstrate the House’s ability to perpetuate John Arnold’s exceptional inventions.
The style of Arnold & Son timepieces is instantly recognisable. The three-dimensional architecture of their movements, the late-18th-century-style cantilever balance-cocks, the George-V-style bridges, the constant quest for multiaxial symmetry and the artfully crafted guilloché dials go hand-in-hand with openworked components, from a single barrel to the full range of grande complication calibres.
Arnold & Son’s remarkably balanced collections are all produced in limited series and distributed around the world through carefully selected points of sale. They are priced fairly, because excellence is bound to honesty.
As Swiss watches with English roots, they stand out without being ostentatious. Arnold & Son timepieces are a delight for the eyes and the mind, and are aimed at customers who are looking for something unique.
Astronomy, Chronometry and World Time
Arnold & Son's three founding principles
Throughout human history, measuring time has always referred to the stars. It was by observing certain stars and understanding their cycle that the first calendars were established with impressive accuracy. It took several millennia before this precision was enclosed in a timepiece like the ones designed by John Arnold.
The golden age of maritime explorations and discoveries ushered this precision into a new technical ideal – determining longitude at sea. Its immediate corollary was the identification of local time, which changed constantly as the observer moved along an east-west axis. Astronomy, chronometry and what we now call world time are thus inextricably linked within one and the same question, to which John Arnold and his son devoted their lives, their art and their genius.
This is how these three dimensions – astronomy, chronometry and world time – have come to be embodied in the House's contemporary timepieces. Echoes of John Arnold's inventions and preoccupations, these pillars represent the foundations on which the Arnold & Son collections are based.
Chronometry: Be accurate
Rate accuracy, which is known as chronometry, is the key requirement of Arnold & Son's contemporary watchmaking. It is the standard of excellence for its collections, the first condition to be met and constantly checked, whether it is at the forefront or in the background of a watch designed by Arnold & Son. It is the most discreet of a movement's characteristics.
When building an Arnold & Son collection, all the thinking is focused on this chronometry. The manufacture calibres are based on advanced technical fundamentals that are not necessarily the best known. One of them is the choice of small, lightweight balances capable of rapidly returning to their isochronous rate after the latter has been disturbed by inevitable everyday shocks. Another is the routine use of large barrels or even two series-coupled barrels to store the energy required for the movement to function. They consequently provide Arnold & Son's manual winding calibres with above-average power reserves of 90 hours and more. A third is the particular attention paid to manufacturing the gear trains, roller-burnishing the pinions and polishing the gear teeth, as well as the precision of the machining and therefore the relative positions of the moving parts, a key concept in rate accuracy.
The tourbillon (or the fact of putting the regulating organ in rotation on its axis to best adjust the effects of gravity on the balance and its hairspring) was patented after John Arnold's death, but it was undoubtedly at the heart of his chronometric research and discussions with his friend Abraham-Louis Breguet, who incidentally assembled his first tourbillon on a John Arnold pocket watch in homage to this great watchmaker. Nowadays, the tourbillon has become a must in Arnold & Son collections.
While the tourbillon was not a complication in John Arnold's time, constant force underpinned the design of his marine chronometers. The regularity of the rate of the sprung balance relies on the consistency of the energy that it receives. However, this naturally fluctuates due to the circular and spiral nature of the mainspring contained in the barrel. To achieve a perfectly smooth torque, in other words a constant force, Arnold & Son uses a one-second constant-force mechanism. Housed just before the escapement, it stores up a small but always equal amount of energy in a secondary spring, the remontoire. Thus, every second, the sprung balance receives very precisely the same force to power its oscillations. These become more even, thereby creating the conditions for a high-precision rate.
Arnold & Son also works with another of John Arnold's historical chronometry indicators: deadbeat seconds, a mechanism that was indispensable to navigators at the time for calculating longitude. This mechanism advances one step each second, rather than six or eight smaller jumps in sync with the frequency of the balance. Instead of the term deadbeat seconds, Arnold & Son prefers a name whose very sound means accuracy: “true beat second”. Its jump is a signature of John Arnold's marine chronometers and a complication that is still alive and well in the House's collections.
Astronomy: Under the sky
The Pole Star, Southern Cross, astrolabes and sextant: measuring time has relied on the recurrence of astronomical phenomena in order to find long, reliable points of reference there that can be used under any conditions. The fruit of the human ingenuity, patience and dedication of countless observers and astronomers from every culture, these markers of cyclical time are foundational for Arnold & Son watchmaking.
Astronomical complications are a signature of Arnold & Son collections, with the moon as the heavenly body of choice, main subject and major inspiration. The distinctive feature of the Brand's moon phase timepieces is that they feature “astronomical” display precision as a matter of course. This term corresponds to an accumulated one-day deviation in the moon phase display every 122 years. Since setting this complication requires great finesse, the Arnold & Son moons generally have a double display with a secondary indicator on the case back next to the movement. This extremely rare display bears witness to Arnold & Son's involvement in all types of development and reflects its favoured themes, which are as much chronometric as astronomical.
Over and above their precision, Arnold & Son's moon phases attract all the light, either with a large moon opening up over half the dial, or with a 12-mm three-dimensional rotating moon, making it the largest of all moons. Whether in two or three dimensions, the moon is always treated as a small work of artistic craftsmanship, composed of materials that are rare in watchmaking such as marble or Paraíba tourmaline, or delicate such as mother-of-pearl, meteorite or aventurine glass. The Arnold & Son moon also shines at night, often with a subtle addition of luminescent material.
World Time: Here, elsewhere, everywhere
With ocean navigation, humankind divided up the world and invented longitudes, which were calculated by comparing the local time, observed using the sun, and the time at a starting point, kept by an extremely reliable timepiece. John Arnold was one of the leading suppliers of chronometers to the British Navy. He was the one who successfully improved the reliability and simplified the production of these indispensable marine chronometers, so much so that he became a benchmark among great explorers such as James Cook and later Dr David Livingstone. The indication of several time zones is therefore integral to Arnold & Son's watchmaking identity.
As this navigation was itself inseparable from cartography, for this world time complication Arnold & Son has chosen to depict a three-dimensional terrestrial hemisphere, making it possible to tell what time it is at any point.
In parallel to this graphic vision, Arnold & Son has developed a second approach to the time elsewhere in the world: with a double tourbillon featuring two distinct rotating regulating organs, making it possible to follow time zones offset by 15, 30 or 45 minutes compared to a full hour – a freedom in terms of setting that remains extremely rare.
Once again, and because this double display is based on a profoundly chronometric complication, Arnold & Son’s fundamental principles are interwoven. One never advances alone; there are always two – if not three – together. This is how a pillar's strength is measured: it relies on the next one, creating the conditions for a solidity that stands the test of time.