Arnold & Son's 260th anniversary celebrations, which began last June, rounds off with the Constant Force Tourbillon 11 reflecting the fellowship between John Arnold and Abraham-Louis Breguet.
Limited to 11 pieces, the commemorative model is inspired by the pocket chronometer No.11, exhibited at the British Museum.
On the main bridge of the historic timepiece, a silver plate is engraved in French, translated as: "The first tourbillon regulator by Breguet incorporated into one of the first works of Arnold. Breguet's homage to the revered memory of Arnold."
Likewise, the Constant Force Tourbillon 11 features a plate with the hand-engraved inscriptions in English: "To the revered memory of J. Arnold and A.-L. Breguet. Friends in their time, legendary watchmakers always."
Arnold & Son is rooted in London while its founder hailed from Cornwall in the Southwest of England. After setting up his business on the Strand, Arnold built his reputation by creating a ring with a half-quarter repeater, presented to King George III in June 1764.
The inventive horologist played a central role in significant events, such as the competition to determine longitude at sea and won several grants and awards offered by the British Board of Longitude.
His marine chronometers included the No.3, which accompanied James Cook on his second voyage in 1772.
Yellow gold edition of the Constant Force Tourbillon 11. Photos © Arnold & Son
Calibre A&S5219 with hand-engraved inscriptions saluting John Arnold and Abraham-Louis Breguet.
After inventing the detent escapement, Arnold constructed his first pocket chronometer in 1773 and acquired patents for a bimetallic balance and a helical balance spring in 1775.
This year saw the opening of the Breguet workshop on Quai de l'Horloge, Île de la Cité in Paris.
During his trips to London between 1789 and 1791, Breguet shared views and knowledge with Arnold. Together they advanced horological science such as by finding the best way of eliminating running errors of balances.
Their chronometric research and discussions culminated in the tourbillon, patented by Breguet in 1801, two years after Arnold passed away.
In memory of their friendship, Breguet mounted the very first tourbillon regulator, which counteracted the effects of Earth's gravity, in Arnold's pocket chronometer No.11.
The exchanges previously included sending their respective sons to train with the other. Accordingly, John Roger Arnold was one of Breguet's apprentices, who came back to London and later succeeded his father in running the family business.
The engraving on the silver plate of the pocket chronometer No.11 additionally states that it was given to Arnold's son in 1808.
The architecture of its movement and finishes of the mainplate, bridge and tourbillon cock echo on the Constant Force Tourbillon 11, which salutes the two watchmaking wizards of the Age of Enlightenment.
Calibre A&S5219 with hand-engraved inscriptions saluting John Arnold and Abraham-Louis Breguet.
The refined tourbillon with a very thin, polished and rounded-off linear carriage bridge.
The design of the tourbillon includes a very thin, polished and rounded-off linear carriage bridge that reveals a variable inertia balance with inertia blocks, recalling sophisticated oscillators in Arnold's chronometers.
The T-shaped retaining spring is inspired by the one used in Breguet's "pare-chute" shock protection system while Arnold's detent escapement has been replaced by a Swiss lever escapement, which is less sensitive to shocks.
The sapphire crystal caseback reveals the tourbillon and the hand-wound mechanical movement, A&S5219, equipped with two barrels to deliver a 100-hour power reserve.
Evoking the faces of Arnold's marine chronometers, the white Grand Feu enamel dial was individually crafted on an 18-carat yellow gold base. Its openings accommodate the constant force mechanism and recessed white opal subdial with black transfer Roman numerals.
The seconds are indicated by the tip of a flame-blued anchor that serves as a structural bridge for the constant force mechanism, which smooths out the energy delivered by the barrels, hence preventing excessive or insufficient torque from affecting the oscillations of the balance in the tourbillon carriage.
The system also allows for a dead-beat seconds indication, in which the direct-drive hand makes successive jumps of exactly one second, like those of marine chronometers.
The open-worked bridge of the constant force mechanism is in 18-carat yellow gold, which also shines on the 41.5mm case, matched with an alligator leather strap in midnight blue.
The Constant Force Tourbillon 11 was entirely developed and produced at the Manufacture La Joux-Perret in La Chaux-de-Fonds, where a new chapter of Arnold & Son began in 2010, following its revival in Switzerland in 1995.
The English heritage is embodied in its 21st century timepieces under the Astronomy, Chronometry and World Time principles that express the ingenuity of John Arnold and his son.
Pocket chronometer No.11 at the British Museum.
Pocket chronometer No.11 at the British Museum.
English watchmaking pioneer John Arnold.
