Arnold & Son Royal Collection – Constant Force Tourbillon

Angus Davies experiences the hands-on delights of the Arnold & Son Royal Collection – Constant Force Tourbillon. As his watch review shows, the constant force escapement provides an apt metaphor for a maison whose energy shows no signs of abating.

This detailed review of the Arnold & Son Royal Collection – Constant Force Tourbillon includes live images and specification details.

Arnold & Son Royal Collection - Constant Force Tourbillon

As any parent will attest, the arrival of a child can prove a culture shock. The days of spending hours, luxuriating in bed, as a newly wed couple, on a Sunday morning cease with the advent of a newborn child.

Sleep deprivation becomes de rigueur with parenthood. Nocturnal hours are disturbed with distressed, colic-fuelled cries. A couple of years later, snatched moments of passion are interrupted with young visitors wanting motherly cuddles.

Ultimately, experienced parents learn to ‘wear out’ the hyper-energetic child. Walks along the coast, interspersed with ball games consume colossal amounts of toddler fuel and fatigue ensues in due course. With parental maturity we learn that infant lassitude is a pre-requisite to a healthy marriage.

As children become increasingly mature and approach adulthood, they acquire wisdom and learn to pace themselves, consuming energy at a more even rate.

Arnold & Son, a name which references English watchmaker John Arnold (1736 – 1799), is a Swiss-based company who clearly understands the wisdom of consuming energy at a smooth, even-handed pace.

The practitioner of haute horlogerie, based in La Chaux-de-Fonds, has combined a constant force escapement with two further complications, a dead-beat seconds and a tourbillon.

The constant force escapement

When a watch is wound, either manually or automatically, the mainspring is placed under increased tension. This tension is a form of energy used to power the indications displayed on the timepiece.

The mainspring unwinds, releasing its energy and returning to a relaxed state. In order to prevent the energy evaporating in the blink of an eye and the hour and minute hands turning at breakneck speed, an escapement is fitted. The standard Swiss lever escapement portions energy into uniform doses and the hands advance with befitting decorum.

However, there is a small problem. Initially, when the watch is fully wound, there is too much energy within the spring barrel and later as the mainspring becomes increasingly relaxed there is insufficient energy. Such variation in energy can negatively influence the amplitude of the movement and, by default, precision.Arnold & Son Royal Collection - Constant Force Tourbillon

A constant force escapement may incorporate a fifth wheel, or other suitable device, to act as an intermediary between the mainspring and the escapement.

Arnold & Son has produced a ‘patented constant force mechanism’. Energy from the mainspring charges a small spring which, in turn, releases a consistent amount of power to the escapement / tourbillon, once every second. The movement is also equipped with twin barrels, one powers the geartrain, whilst the second spring barrel tops up the first when the ‘torque output drops below optimal.’

Dead-beat seconds

The ‘patented constant force mechanism’ from Arnold & Son is paired with a true-beat seconds, ‘seconde morte’ or ‘dead-beat seconds’. This complication is a speciality of the maison and continues to beguile purists with its andante gait. Moreover, despite its seemingly simple operation, much complexity is employed to realise this complication.


The final complication to feature on this stunning timepiece is the tourbillon, patented by Abraham-Louis Breguet in 1801. The famous, Paris-based watchmaker was a close friend of John Arnold and would almost certainly have collaborated with the Englishman when developing his ‘whirlwind’ device. Indeed, ‘Breguet’s first ever tourbillon cage (no. 169) was mounted in John Arnold’s No.11 movement, a watch that can be found today in the British Museum’.

The dial

The dial exploits the notion of symmetry to comely effect. The twin mainspring barrels are positioned in the upper region of the dial and are held in position by two open-worked barrel bridges which appear to kiss. Furthermore, they exhibit highly agreeable hand-chamfered edges.

Arnold & Son Royal Collection - Constant Force Tourbillon

Turning one’s gaze to the southern hemisphere of the dial, the constant force mechanism is positioned between 7 and 8 o’clock, with the central dead-beat seconds hand floating above. Positioned opposite, the tourbillon cage is freely disclosed and to the casual observer may appear to be a facsimile to its neighbour. It is not.

Arnold & Son Royal Collection - Constant Force Tourbillon

Arnold & Son has been very ingenious, the bridges which retain the constant force mechanism and the tourbillon cage share similar dimensions, proffering a seemly symmetry and balance. Indeed, the four aforementioned dial-side bridges bestow a wonderful sense of harmony.

The straight sides of the hour and minute hands give way to curved tips which point to succinct markings on the anthracite chapter ring. The warm, golden tones of the hands complement the faceted and applied hour markers, reinforcing the traditional character of this timepiece.

Spanning the brushed central section of the timepiece, part of the crown wheel can be seen, again, connecting the wearer to the inner thought processes of the movement.

The case

The Arnold & Son Royal Collection – Constant Force Tourbillon is a horological leviathan, measuring 46mm in diameter. This is not surprising when one considers the myriad of technical features at play. However, I found the watch accorded a very agreeable fit.

Arnold & Son Royal Collection - Constant Force Tourbillon

One reason I suspect the watch proves comfortable to wear is that the crown, whilst having a significant diameter and therefore proving simple to operate, is shallow and does not protrude unduly from the caseband. This attribute is most welcome. I have worn similar sized watches in the past, sporting bulbous crowns that have gouged my arm with their intrusive dimensions.

Arnold & Son Royal Collection - Constant Force Tourbillon

The case construction is more complex than may at first appear. The caseband is adorned with several swage lines and has a cambered profile, proving wider near the dial than the circumference, adjacent the caseback. Indeed, the sides of the watch are not straight, but delightfully curved and graceful in form. Because the diameter of the caseback is less than the dial surface, the watch sits more comfortably, eschewing excess girth where it is not required.

The lugs are highly polished on all surfaces, save for their exterior, vertical flanks which are satin-brushed. This satin-finished plane is actually an insert which can be removed by a competent watchmaker and easily refurbished. Clearly, Arnold & Son has given much thought to the longevity of the watch and on-going upkeep.

Arnold & Son Royal Collection - Constant Force Tourbillon

The dorsal area of the watch is equipped with a sapphire crystal, allowing the wearer to absorb the exquisite finishing of the movement.

The movement

The hand-wound A&S5119 manufacture movement is constructed nickel-silver and steel, with palladium treated bridges.

Arnold & Son Royal Collection - Constant Force Tourbillon

Arnold & Son Royal Collection - Constant Force Tourbillon

Whilst this watch has a predominantly classical appearance, the NAC grey treatment of the mainplate exhibits a contemporary aesthetic. This seemingly split-personality works well and the marriage of materials harmoniously fuse together.

The screw heads have chamfered rims and slots which brilliantly gleam, courtesy of sublime mirror-polishing. Both the jewel and screw sinks are, again, beautifully polished. The finissage of this timepiece is impeccable.

The balance wheel is an interesting design and the creative souls at Arnold & Son have clearly embraced ‘blue-sky thinking’, illustrated by the use of C-shaped inertia weights located ‘in-board’, mitigating the disruption of the airflow around the balance.

Where Arnold & Son differentiates itself from many other purveyors of haute horlogerie timepieces is in designing unique movements for limited edition watches. I have no doubt the Arnold & Son Royal Collection – Constant Force Tourbillon will have required numerous hours of research and development to realise, yet the company plans to make only 28 pieces in 18-carat red gold. This approach by the maison bestows both intrigue and individuality in equal measure.

Closing remarks

In recent years, Arnold & Son has repeatedly demonstrated its consummate skill at creating interesting new timepieces. These watches contain complications once found in pocket watches of the 18th century, now combined to magnificent affect, presented in wristwatch form and distilled to perfection.

The brand does not choose to replicate the past so much as take inspiration from the work of John Arnold and his contemporaries and in so doing creates its own new chapter in the history of horology.

The constant escapement appears to encapsulate the paradigm of Arnold & Son. The innovative company seems to indulge the cognoscenti with a steady flow of fascinating new timepieces. Indeed, based on my experience with the Arnold & Son Royal Collection – Constant Force Tourbillon, the energy and creative power of this Swiss brand shows no sign of abating.

Technical Specification

  • Model: Arnold & Son Royal Collection – Constant Force Tourbillon
  • Reference: 1FCAR.B01A.C112C
  • Case: 18-carat red gold; diameter 46.00mm; water resistant to 3 bar (30 metres); sapphire crystal to front and caseback.
  • Functions: Hours; minutes; true-beat seconds; tourbillon; constant force
  • Movement: Calibre A&S5119, hand-wound movement; frequency 21,600 vph (3 Hz); 39 jewels; power reserve minimum 90 hours.
  • Strap: Hand-stitched brown alligator leather with 18-carat red gold pin buckle
  • Limited Edition: 28 pieces

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