A Complication Rooted in History

The constant force problem is as old as mechanical timekeeping itself. Spring-driven movements deliver irregular torque as the mainspring unwinds; this torque variation corrupts the amplitude of the balance wheel and, ultimately, the rate. John Arnold solved this aboard his marine chronometers through the fusée-and-chain:  a conical pulley that progressively compensated for the declining force of the spring. Breguet, Arnold’s close friend and occasional collaborator, approached the isochronism problem from the escapement perspective. Their shared obsession with precision chronometry is the intellectual bedrock on which the CFT11 stands. Arnold & Son’s modern solution replaces the fusée entirely with a patented constant force device positioned between the going train and the tourbillon, re-arming a finely adjusted spiral once per second to deliver perfectly regulated energy to the escapement.

The Dial

The dial is the watch’s most striking triumph. Built on an 18-carat yellow gold base and finished with white Grand Feu enamel, it achieves a depth and luminosity that photographs genuinely cannot reproduce. A concave subdial in white opal occupies the upper left quadrant, displaying hours and minutes via Roman numerals and flame-blued hands; its inclined design catches light in ways that give the dial a three-dimensional quality unusual for any price point. To the right, partially exposed beneath a sculpted 18-carat gold bridge, sits the constant force mechanism itself, rotating visibly over the course of one minute. The dead-beat seconds, each one-second jump delivered by a flame-blued anchor bridge – the house symbol – echo the detent chronometers that Arnold built for the Royal Navy. It is a dial that rewards sustained attention.

The Movement: Calibre A&S5219

The hand-wound calibre A&S5219 is entirely developed and assembled in La Chaux-de-Fonds, measuring 33mm in diameter and 10.48mm in thickness. Two barrels in series provide a 100-hour power reserve at a frequency of 21,600vph (3Hz), and the constant force mechanism ensures that energy transmitted to the tourbillon remains unvarying throughout that duration. The one-minute tourbillon, visible from the caseback, features a variable-inertia balance with inertia blocks inspired by Arnold’s own chronometer oscillators. A T-shaped retaining spring on the tourbillon bridge recalls Breguet’s pare-chute anti-shock system, here rendered in polished steel beneath a linear, rounded carriage bridge. The movement finishes in English style: engraved plates, bevelled edges, and a hand-inscribed dedication on the barrel bridge reading: ‘To the revered memory of John Arnold and Abraham-Louis Breguet. Friends in their time, legendary watchmakers always’.

The Case

The fully polished 18-carat yellow gold case measures 41.5mm in diameter and 13.7mm in thickness. The size is a consequence of stacking a constant force mechanism and a tourbillon within a single calibre. A domed sapphire crystal sits on the dial side, while a flat sapphire crystal with an anti-reflective coating covers the exhibition caseback. The crown features a fluted edge and the Arnold & Son anchor in relief. Water resistance is rated at 30 metres. The watch comes with a hand-stitched midnight-blue alligator strap with black alligator lining and a yellow gold pin buckle.

Final Word

A limited edition of eleven pieces, priced at €155,000 (incl. VAT), places the CFT11 firmly in the territory of haute horlogerie – and rightly so. The combination of a genuinely meaningful historical narrative, in-house constant force engineering, Grand Feu enamel craft, and exhibition-grade tourbillon finishing makes this one of the most coherent and compelling complications released in recent memory. Arnold & Son have built something that John Arnold and Breguet would both recognise and – one suspects – approve of.