TAG Heuer is marking the rollout of its new-and-improved, and in-house, carbon hairsprings – timed to coincide with the 350th anniversary of the hairspring’s invention – with a pair of chronographs: the Monaco Flyback Chronograph TH-Carbonspring and Carrera Chronograph Tourbillon Extreme Sport TH-Carbonspring.

More than just two new watches, the TH-Carbonspring is a notable technical achievement that might promise an entirely new generation of TAG Heuer movements equipped with oscillators that boast all of the advantages of silicon, but with added robustness. Protected by several patents, TH-Carbonspring is also the result of a fascinating process of research and development to overcome a surprising problem.

Kitted out in carbon composite dials and cases, the two watches are centred on TAG Heuer’s latest-generation carbon-nanocomposite balance springs, with each being a limited edition of just 50 pieces

Initial thoughts

Both models serve as a launch platform for TAG Heuer’s improved and industrialisation-ready carbon hairspring. While the brand has been flirting with carbon hairsprings since 2019, its use of the technology has been intermittent and on limited scale.

TAG Heuer explains previous attempts at carbon springs were not up to the brand’s standards, which is to say the hairsprings did not perform as expected and could not be produced at scale. The new TH-Carbonspring indicates TAG Heuer has perfected the technology to make reliable hairsprings, which might lead to broader adoption within the LVMH’s stable of watch brands. In fact, the material might even rival silicon in the future, at least for LVMH marques.

The main advantages of carbon hairsprings are the total magnetic resistance (since carbon is naturally non-magnetic), lightness, and ability to be formed in any shape imaginable — especially useful when optimising hairspring geometry. These qualities are very close to silicon’s traits, but carbon holds an advantage, higher yield strength, making it more robust when handled by a watchmaker during assembly or service.

Assuming TAG Heuer can industrialise the carbon hairspring and install it across its production, as is the goal, the technical achievement of TH-Carbonspring is significant. Ironically, the two watches are fairly low-key symbols of this achievement, both have a similar monochromatic aesthetic  due to the overwhelming use of carbon composite on the exterior — though they are as different as they come. 

Notably, the movements in the two watches are distinguished not only by the carbon hairspring, but in terms of decoration as well. Both the Monaco and Carrera share a distinctive chequerboard finish that was first implemented on the one-of-a-kind Monaco made for the Only Watch charity auction. Though not hand applied as with the unique piece, the decor does set these calibres apart.

The Monaco Flyback TH-Carbonspring is undoubtedly the better looking of the two – though I admit I’ve always been a fan of the Monaco. Fashioned out of forged carbon, the square Monaco case is very different from the colourful piece that famously graced Steve McQueen’s wrist. The monochromatic look suits the square design well, all while keeping the dial sufficiently legible. 

The classic dial layout of the Monaco is retained, but with a clever touch in the form of a spiral motif on the dial. In keeping with the iconic twin register look, the Monaco Flyback employs a “ghost” register for the running seconds at six o’clock. 

At CHF17,000 the Monaco in carbon is a little pricey compared to the standard Monaco models, but it offers a lot more in all respects, from the case material and the movement technology. That, combined with the small edition size, rationalises the price.

The Carrera, on the other hand, is still a value-minded complication, but dressed in a full carbon ensemble. The result is not as appealing as the Monaco, with some design choices here looking forced. The marbled texture of forged carbon are more prominent than on the Monaco, while the lugs attempt to resemble an integrated bracelet. Much of the aesthetic result is due to the design of the Carrera Extreme Sport rather than the carbon livery.

While the Carrera might not be to everyone’s taste, its value lies in the in-house chronograph movement, adapted for a flying tourbillon regulator which puts the TH-Carbonspring front and center.

The two movements employed to showcase the new TH-Carbonspring point to TAG Heuer moving upmarket in terms of both industrialisation capability and quality. Performance chronographs from the likes of Rolex, Omega and Breitling are almost all chronometer-certified while also employing advanced technology, especially in the oscillator.

TAG Heuer was always a little behind in that respect. With its new hairspring technology, TAG Heuer has finally a fighting chance of reaffirming its place as a chronograph maker of note, with innovation-fuelled creations.

The carbon evolution

With the hairspring turning 350 years old, we already delved substantially into its history and evolution driven by materials science. The final important development in the evolution was the silicon hairspring with its easy mass-production, tight tolerances, and isochronal geometries, not to mention a useful resistance to magnetic and temperature influence.

Carbon, however, might do one better. For all its qualities, silicon still suffers from inherent brittleness, which makes such hairsprings susceptible to snapping due to shock or even mishandling during service. This weakness, combined with the fact that the patent for silicon hairsprings limits their use to a select few companies, drove the engineers at the TAG Heuer Institute (now renamed the TAG Heuer Lab) to search for other non-metallic materials that to replace alloy springs.

TH-Carbonspring sample, with a distinctive geometry.

TAG Heuer’s first carbon nanocomposite hairsprings hit the market in 2019. The new oscillator promised all the advantages of silicon (non-magnetic, isochronal geometry) while boasting a superior yield strength. At the time, TAG Heuer claimed the new hairsprings could withstand 5,000 G of acceleration — a value which would snap silicon and severely bend alloy springs. 

These first versions the carbon spring were made out of carbon nanocomposite, essentially a vertical bundle of carbon nanotubes (with diameters of 3 to 7 nanometers), held together by a rigid carbon matrix, almost like a forest of nanotube trees. The tubes were arranged perpendicular to the spiral’s plane, with each nanotube parallel to the rotational centre of the hairspring, namely the balance staff. 

PVD chamber with wafer plate.

The patent WO2017220672A1 filed back in 2017 detailed an original two-part production process for these carbon nanotube hairsprings. The first step was “growing” the nanotube structure with a PVD (Physical Vapour Deposition) method, and the second step was filling in the core carbon matrix, the adhesive that held the tubes together. The process was done on wafers similar to those used for silicon etching. 

The resulting carbon nanocomposite hairspring was elastic and strong, with the particular structure lending it a high elastic limit. A different patent addressed the issue of temperature self-compensation and the thermo-elastic coefficient. Paired with a proprietary geometry that would keep the rotation center coincident with the balance axis (an issue broadly covered in a past story on hairspring overcoils), the new carbon springs looked like a strong rival to replace silicon.

The promising system was only used sporadically by TAG Heuer (and sister company Zenith), clearly a sign that the hairspring was not as performing as intended — although the concept looked foolproof. A few select timepieces featured the new spring, but the carbon technology never reached the industrialised scale of its silicon counterpart. 

With the new TH-Carbonspring, TAG Heuer hints at the full potential for industrialising its improved carbon springs – the brand’s annual production of mechanical watches is into six figures. The fact that the two new models are each limited to 50 pieces is most probably related to their costly forged carbon cases and carbon accented dials, rather than the hairsprings themselves. 

Now watertight

Though TAG Heuer hints at a new and improved manufacturing process for the carbon springs, it has kept quiet about the details that make the invention ready for mass production. We did however manage to trace patent WO2025114588A1, filed at the end of last year and published earlier this year in June, which describes the additional manufacturing steps and hints at the issue that plagued the past versions of its carbon hairspring.

The patent heavily builds on the initial one from 2017, but explains how the composite material, in its raw form, is water permeable. This means that the original springs absorbed water and other liquids, which in turn affected their qualities (mass, natural frequency). In any watch there are plenty of lubrication points — not to mention the ever-present humidity in the air, all which seem to have negatively affected the original carbon springs. 

The issue of material permeability does not immediately come to mind in the field of hairspring design, since metal alloys and silicon are inherently non-permeable. The issue of oxidation was an issue, especially with alloy springs, but separate from permeability.

In the earlier version of TAG Heuer’s carbon hairspring, the nanotube “forest” turned into a sponge of sorts, with its porous surface absorbing humidity into the spaces between the tubes. The new patent explains the unwanted effect was only noticed in serial-production springs, so it was completely unforeseen during the design and development phase.  

At its core, the new patent describes a method of surface passivation, such that the hairsprings become hydro- and oleophobic. In other words, the hairspring will not absorb any liquids that may come in contact with its surface.

Through a bend of chemistry and physics, TAG Heuer engineers developed a process of treating the nanocomposite springs with specific carbon chains that render the final product impervious to humidity. The process itself is similar to electrolysis in some ways, but requires specialised chemical reactors and needed some extensive experimentation to be fine-tuned. 

With the implementation of this final step, the TH-Carbonspring seems to be a mature technology that is finally able to fulfil its potential. While it shares some qualities with silicon springs, mainly the imperviousness to magnetic fields and optimised geometry, it surpasses silicon in two ways: lightness and much higher yield strength. 

A lighter hairspring is more faithful to the theoretically perfect sprung regulator, which doesn’t take into account the spring’s own mass and inertia. The higher yield strength allows the TH-Carbonspring to withstand shocks, and important allows watchmakers to handle them like alloy springs during assembly and servicing, without fear of breakage.

The Monaco

Perhaps the most emblematic model in TAG Heuer’s line, the Monaco is dressed in carbon for this limited edition, while keeping the design cues of the original.

The square chronograph retains its classic, well-proportioned 39 mm case that is now sculpted from carbon composite. Being fashioned out of carbon, the case is light and durable. The material not only gives the watch a stealthy and raw look, but also makes each piece unique, since the carbon graining has a different orientation in each batch of material.

Also rendered in carbon composite, the dial is milled with a circular motif made up of wide bands that spiral from the center — a nod to the coils of a hairspring. 

The white hands and numerals maximise legibility, while the intentional omission of a defined sub dial for the small seconds is laudable, since it preserves the original Monaco look. The small seconds hand itself is blackened and only visible under close scrutiny. 

The Monaco Flyback TH-Carbonspring is powered by the TH20-60, an in-house movement derived from the more basic TH20-00 developed by Carole Forestier-Kasapi and her team. Compared to the basic version of the caliber, the TH20-60 is updated with a flyback function as well as the TH-Carbonspring system. 

The TH20-60 caliber is at its core a competent and modern chronograph movement, with a respectable power reserve of 80 hours and a standard 4 Hz rate. It benefits from a column wheel actuation system and a vertical clutch — both marks of modern performance chronographs. This new version updates the regulator with a TH-Carbonspring, while curiously keeping the simplistic raquette regulating system. 

The choice of an inexpensive index regulator, compared to the more advanced free-sprung option is odd — especially for a timepiece which is centred around a new high-performance regulator. Although it is not advertised on the dial, the TH20-60 is COSC-chronometer certified.

The caliber is clearly machine-finished, with the bridges finished with a chequered flag motif inspired by the brand’s motorsport ties. Being a round movement fitted into a larger square case, the TH20-60 requires a substantial movement ring, which is also tastefully finished with the same pattern.

A chronograph and tourbillon

Compared the almost-subdued Monaco, the Carrera Chronograph Tourbillon Extreme Sport TH-Carbonspring is an aggressively styled 44 mm. Whereas the Monaco leans into classic looks, the Carrera TH-Carbonspring is modern. The large case follows the lines of the traditional Carrera form, but is bulked up and accented with touches like the “integrated” strap.

It is fashioned from forged carbon, as are the chronograph pushers and crown. Also in carbon is the tachymeter bezel that features lacquered numerals. 

Much like the Monaco, the Carrera is very legible, something which can’t be said for many monochromatic watches. The carbon spiral motif is present on the dial as well, although it is decidedly larger than the one used for the Monaco. The spiral pattern is emanates from the tourbillon cage, as opposed to the center of the dial, which is a thoughtful design choice.

The defining visual trait of the model is surely the flying tourbillon regulator, positioned a little too low at the 6 o’clock position. The cutout aperture is larger than the chronograph sub registers and for some reason makes the tourbillon look a little small. This and the fact that it cuts into the outer minute track leaves the impression of a slightly lopsided dial. 

Powering the Carrera is the TH20-61 — yet another iteration of the basic TH20-00. For this version, TAG Heuer kept the chronograph works and only altered the going train and base plate to accommodate the dial-side tourbillon regulator.

The TH-Carbonspring is paired here with a free-sprung balance, which is fitting at this price point. The TH20-61 manages 65 hours of power reserve while beating at 4 Hz. This is less compared to the TH20-60 in the Monaco and the difference speaks of to the energy consumption of a tourbillon regulator. The TH20-61 is chronometer certified as well and shares the same finishing as the TH20-60. 

Key facts and price

TAG Heuer Monaco Flyback Chronograph TH-Carbonspring
Ref. CBL5190.FT6313

Diameter: 39 mm
Height: 14.1 mm
Material: Forged carbon, DLC-coated titanium caseback
Crystal: Sapphire
Water resistance: 100 m

Movement: Cal. TH20-60
Functions: Hours, minutes, seconds and flyback chronograph
Frequency: 28,800 beats per hour (4 Hz)
Winding: Automatic
Power reserve: 80 hours

Strap: Rubber strap with DLC-coated titanium folding clasp

Limited edition: 50 pieces
Availability: Starting from December 2025
Price: CHF17,000

TAG Heuer Carrera Chronograph Tourbillon Extreme Sport TH-Carbonspring
Ref. CBU5091.FT6305

Diameter: 44 mm
Height: 15.4 mm
Material: Forged carbon, DLC-coated titanium caseback
Crystal: Sapphire
Water resistance: 100 m

Movement: Cal. TH20-61
Functions: Hours, minutes, chronograph, and flying tourbillon
Winding: Automatic
Frequency: 28,800 beats per hour (4 Hz)
Power reserve: 65 hours

Strap: Rubber strap with DLC-coated titanium folding clasp

Limited edition: 50 pieces
Availability: Starting from the first quarter of 2026
Price: CHF40,000

For more, visit Tagheuer.com.

Often behind every watch brand’s marketing and image is an overarching influence that can be subtle or explicit. For Patek Philippe, that influence reveals a long arc of intention, carried across centuries, shaped by consistency, and reinforced through a remarkable alignment between product and message.

From its early days in royal courts to modern-day exhibitions in New York and Shanghai, the company has approached communication as a reflection of its philosophy. Over nearly two centuries, Patek Philippe has maintained a consistent approach to communication – measured, stable, and aligned with the brand’s long-term perspective.

The manner of Patek Philippe telling its own story is perhaps as interesting as its watches. We trace the way in which Patek Philippe has communicated over time, from introducing itself to the mind of the client, to adapting to a changing world, all while remaining aligned with its values. We also examine the brand’s choices in language and imagery, looking in particular to its early references to inheritance, which evolved into the familiar campaign that continued across decades.

Launched in 2025, but perhaps enjoyed by many generations to come

Foundations and Royal Recognition (1839–1877)

When Patek Philippe was founded in 1839, the idea of advertising a luxury watch was almost nonexistent. Most manufacturers relied on trade reputation, medals at international exhibitions, and word-of-mouth among wealthy clientele. In contrast to today, almost all watches were sold by third-party retailers and distributors who were primarily responsible for marketing, leaving watchmakers to just make watches.

The 19th century’s dominant marketing platforms were world’s fairs, retailers’ printed catalogues, and window displays in prestigious stores. Public advertising was largely limited to basic listings in trade directories or society newspapers. Mass communication held little relevance for a product often made for heads of state and captains of industry.

While more established firms like Vacheron Constantin and Breguet drew on deeper histories and longstanding networks, Patek Philippe, then still a newcomer, advanced through deliberate participation in exhibitions, careful retail placement, and the symbolic power of its keyless winding mechanism. It built an early reputation through institutional exposure and personal association.

The brand’s posture was defined by selectivity. The company appeared in settings that conveyed legitimacy: international fairs, respected retailers, and commissions that carried public weight. Communication was structured through deed rather than display, for instance a patent filing, a jury medal, a royal presentation. In this framework, the brand’s identity took shape through action and context, expressed in its creations, presentation, and reception by tastemakers who shaped standards of excellence.

Opening of the Great Exhibition in London by Queen Victoria on May 1st 1851. Image – Wikipedia

The company’s royal breakthrough came in 1851 at the Great Exhibition in London, where Queen Victoria was gifted a blue enamel pendant watch that is today in the Patek Philippe Museum.

This highly visible endorsement, paired with a gold medal awarded at the fair, immediately linked the firm to royalty. But Patek Philippe’s reputation was also built on technical distinction.

One of its key innovations was Jean Adrien Philippe’s 1844 invention of the keyless winding and setting mechanism, an elegant solution that allowed the user to wind and set the time through the pendant. It eliminated the need for a separate key and set a new standard for simplicity and refinement in horology. As noted in Patek Philippe: The Authorized Biography, this technical contribution was one of the defining factors in the firm’s early acclaim.

Philippe’s American patent filed in 1876 for his keyless winding system invented in 1845

In the same year that Queen Victoria acquired her watch, Patek Philippe also began a formal retail partnership with Tiffany & Co. in New York. This marked an early recognition of the American market’s potential and reflected a clear strategy of working through trusted intermediaries.

Tiffany’s, already associated with refinement and a discerning clientele, became an important representative of the brand’s identity in the United States. According to John Reardon’s Patek Philippe in America, this partnership laid the foundation for the brand’s long-standing success in the United States, decades before the establishment of Patek Philippe’s own subsidiary in the United States, the Henri Stern Watch Agency (HSWA).

Through this partnership, Patek Philippe entered the American market with cultural and commercial credibility. This early relationship helped shape the way the brand would be perceived in the United States – a European marque attuned to American standards of taste and trust.

Tiffany & Co. at 15 Union Square West in New York City in the 1870s. Image – Curbed/flickr

By the late 19th- and early-20th century – by then the brand counted amongst its clients Queen Louise of Denmark, Pope Pius IX, and Emperor Franz Joseph of Austria – Patek Philippe’s image had been shaped by mechanical innovation, refined design, and association with influential patrons. Reputation developed through presence, earned by timely inventions, high-profile endorsements, and strategic alignment with the values of cultural and technical excellence.

Retail Presence and Early Advertising (1878–1902)

By the final quarter of the 19th century, the landscape of marketing was shifting. Industrialisation had introduced new consumer categories, and advertising was beginning to find its form through illustrated posters, branded packaging, and paid placements in newspapers and journals. In Paris, London, and New York, luxury goods were increasingly promoted through high-end department stores, theatrical catalogues, and ornate retail displays designed to attract the growing bourgeois clientele. Branding was becoming visual, and advertising more assertive.

An 1881 calendar card from American Patek Philippe retailer D. Valentine in Syracuse, New York. Image – Collectability

Patek Philippe, however, maintained a position at the edges of this change. Its watches appeared in public-facing formats, but always filtered through a layer of curatorship, either through the jewellers who carried them or through participation in horological exhibitions. According to Patek Philippe: The Authorized Biography, the firm’s retail presence during this period followed a strict policy of select representation, offering visibility without mass availability. Retail operated more like a gallery system: select dealers in major cities showcased the brand in controlled environments, and promotion came through the reputation of the seller.

The brand’s name began appearing in trade publications and society listings, often alongside descriptions of medals or royal patrons. These early advertisements were rarely self-authored; more often they were short notices placed by retailers or distributors, sometimes accompanied by stock line engravings or general claims about precision and elegance. These printed mentions conveyed prestige without overt persuasion, and reflected the brand’s preference for mediated presentation.

1901 advertisement by French retailer Paul Maux mentioning Patek Philippe in La Vie Montpelliéraine. Image – Gallica

What distinguished Patek Philippe in this period was its insistence on selectivity. Where other watchmakers expanded rapidly through larger dealer networks and broader product lines, Patek Philippe limited its exposure. Distribution was kept narrow. Clients were addressed indirectly, through the prestige of the store or the printed mention in a reputable journal. No slogans, no testimonials, no pricing tables, just presence, reputation, and the quiet authority of craftsmanship.

At the turn of the century, as illustrated advertising began to saturate the urban press, Patek Philippe stood apart by continuing to rely on positioning. Its name might appear in a jeweller’s window or on the title page of a catalogue, but the watch remained the subject of attention instead of the object of promotion.

Heirloom Messaging and United States Agency Formation (1903–1948)

In the early decades of the 20th century, advertising grew increasingly sophisticated. The rise of consumer culture brought with it the language of aspiration, sentiment, and identity. Brands across industries began to craft messages that appealed to emotion rather than function. In print media, especially in the United States, advertisements spoke in full paragraphs, paired with ornate illustrations or bold type, and began to tell stories around the product. Luxury, once assumed, now required narrative.

Atlanta jeweller Maier & Berkele’s 1903 advertisement. Image – Collectability

Patek Philippe moved through this shift at its own pace. The firm remained measured in tone and limited in exposure, though signs of adaptation began to emerge, particularly in the American market. In 1903, American jeweller Maier & Berkele ran an advertisement describing Patek Philippe as “worth passing from father to son.”

According to Patek Philippe in America, this marked one of the earliest known expressions of the heirloom concept in the brand’s American messaging. It was a short sentence, but a decisive one. It introduced the concept of generational ownership, framed in terms of continuity and long-term significance. This phrasing quietly set the tone for what followed.

Throughout the 1910s and 1920s, Patek Philippe’s advertising presence remained modest. Dealer ads appeared occasionally in major city newspapers, typically within jeweller listings or in seasonal gift guides. The language often emphasised precision and Swiss heritage. Imagery was limited, and the text carried more weight than visuals. In tone, these ads aligned with the formality of the period, subdued, direct, and positioned toward individuals who valued tradition.

Patek Philippe ad published by the HSWA in 1937. Image – Private Archive

A turning point came in 1932, when the Stern family acquired Patek Philippe. Family ownership, established during a period of global economic strain, reinforced the company’s long-term outlook and shaped its strategic posture for the decades ahead.

In the United States, this led to the creation of HSWA in 1942, a dedicated distributor that would define the brand’s presence in the American market. Named after Charles Stern’s son Henri, who had been sent to the United States to oversee the crucial market, HSWA served as both a logistics base and a communications hub, responsible for translating the brand’s identity into the language of American print culture.

Patek Philippe ad, published by the HSWA in 1942. Image – Private Archive

By the late 1940s, HSWA began to shape a more intentional narrative for Patek Philippe in the United States. In 1945, a newspaper ad described the watch as one “to be treasured from generation to generation.” Four years later, in 1949, a similar campaign featured the line: “Your great-grandson may wear this watch.” These messages framed the product as a personal legacy, placing emphasis on continuity and inheritance over status. They marked the beginning of a campaign language built around permanence and time understood in familial terms.

Many luxury brands of the period turned to celebrity endorsement and visual glamour. Patek Philippe followed a different path, focusing its voice on longevity, stewardship, and personal significance. This direction, quietly introduced through HSWA’s ads, set the foundation for what would become the brand’s most enduring campaign. Its roots were already visible in the understated language of inheritance.

The American Moment Begins (1949–1969)

Postwar America became the world’s most influential consumer market, and with that came a rapid transformation in advertising. The 1950s and 1960s saw the rise of full-page newspaper placements, television commercials, celebrity testimonials, and the golden age of Madison Avenue ad agencies. Brands across industries leaned into mass communication, and aspirational marketing became central to luxury goods, from automobiles to fashion to watches.

Patek Philippe ad, published by the HSWA in 1955. Image – Private Archive

For Patek Philippe, this era marked the beginning of a structured presence in the United States, largely directed through HSWA. According to Patek Philippe in America, HSWA operated with a high degree of autonomy, shaping brand perception through selective advertising, retail programming, and strategic restraint. Rather than adopting the tone or scale of mainstream luxury advertising, the agency developed its own approach, one that preserved the reserve of the brand while finding resonance with the American consumer.

During these two decades, Patek Philippe advertising in the United States took on a slightly more narrative voice. Ads placed by the HSWA in publications such as The New Yorker, Town & Country, and The New York Times maintained formal, concise language. The themes continued to center around permanence, craftsmanship, and intergenerational value. Watches were presented as symbols, carrying meanings of achievement, responsibility, and continuity.

Patek Philippe German ad, published in 1957. Image – Private Archive

Print designs from this period were restrained: black-and-white layouts, serif typography, and minimal imagery. A single reference, often shown in profile, might appear beside a short paragraph that referenced Geneva, tradition, or longevity. Product copy was surrounded by white space, creating a sense of calm and clarity uncommon in the era’s increasingly crowded ad pages.

Although mass-market brands were turning to celebrities and product glamour, Patek Philippe emphasised anonymity and discretion. No faces were used. No slogans repeated across pages. If there was emotion, it was quiet, a gesture toward pride in one’s legacy, or the dignity of owning something that would outlast its first wearer. According to Patek Philippe: The Authorized Biography, this approach reflected the company’s broader resistance to trend-based visibility in favour of long-term meaning.

Patek Philippe Australian ad, published in 1965. Image – Private Archive

This period also saw the brand’s first steps into exhibition-based marketing in the United States. In-store events at authorised retailers, sometimes accompanied by displays of rare timepieces or historical documentation, gave clients a curated experience. These events functioned as soft-spoken brand theatres: part education, part aspiration, and entirely in tune with the company’s communication values.

The American strategy in these years helped prepare the ground for future campaigns. It introduced narrative restraint in a market known for spectacle, and it framed the Patek Philippe watch as a personal object, drawing attention through presence and quiet focus over overt appeal.

Creative Identity and Exhibition Strategy (1970–1985)

As the luxury market expanded in the 1970s, advertising entered a new phase defined by bold imagery, lifestyle branding, and increasing emphasis on visual association. Magazines became vehicles for symbolic identity, glossy pages filled with models, exotic settings, and logos treated as cultural signals.

In the watch industry, this translated into campaigns built around celebrity wearers, sport affiliations, and glamour photography. Brands such as Omega and Cartier leaned into personality-driven promotion, while quartz disruption pushed others toward more urgent messaging.

Patek Philippe 1974 to 1978 ad campaign. Image – Private Archive.

Patek Philippe moved through this period on its own terms, refining a language of understatement. Its visual identity in advertising remained minimal, clean lines, plain backgrounds, and isolated images of the watches themselves. Headlines were succinct, copy was measured, and the tone remained aligned with values already established: discretion, permanence, and generational appeal. This period demonstrated the brand’s commitment to continuity in the face of increasing visual noise.

A defining moment of this period came in 1976 with the introduction of the Nautilus. Patek Philippe launched the watch with a paradox: “One of the world’s costliest watches is made of steel.” Showing the watch against a simple background, without wrist or wearer, the advertisement disrupted expectations. In a market where steel typically signified utility or affordability, the line challenged assumptions and asserted value through confidence and restraint.

According to Patek Philippe: The Authorized Biography, this campaign was conceived to break through the visual clutter of the period without abandoning the brand’s voice. The message was quiet and deliberate: value could be redefined without the need for ornament or explanation.

1980s ads by Australian retailer J. Farren Price announcing in-house exhibitions. Image – Private Archive

Alongside this shift in product language, Patek Philippe began experimenting more deliberately with exhibitions. The United States market, where HSWA continued to serve as strategic lead, became a testing ground for experiential engagement. These exhibitions went beyond sales; they were curated presentations of history, mechanics, and craft. As documented in Patek Philippe in America, they offered clients and journalists a deeper view into what the brand considered essential: lineage, innovation, and restraint.

These exhibitions stood apart from typical trade show appearances. Patek Philippe focused on intimate displays, often presented in collaboration with museums or prestigious retailers. Archival materials, vintage watches, and craft demonstrations were used to tell a story of continuity, of a company moving forward while keeping its past fully present.

The overall marketing stance during this period resisted the dominant trends. While others embraced movement, speed, and celebrity, Patek Philippe deepened its commitment to controlled visibility. Even in the release of a sports watch, the campaign maintained composure. And in each exhibition, the brand reaffirmed that its message, like its watches, was built to endure.

The Bittel Era and Global Messaging (1986–1995)

By the mid-1980s, luxury advertising had settled into its mature phase. Brands sought consistency across markets, cultivating global identities anchored in logo, typography, and tone. Prestige was visualised through lifestyle photography, yachts, private jets, Alpine chalets, and advertising emphasised access to a particular world, often through association with celebrities or aspirational imagery. In the watch industry, many leading names relied on large-format magazine ads, recurring ambassadors, and high-volume exposure across both fashion and business press.

The Calatrava Ref. 3919 inaugurated Patek Philippe’s first global ad campaign in 1987 . Image – Private Archive

Under René Bittel, who led Patek Philippe’s international marketing through much of the 1980s and early 1990s, the brand sharpened its visual and linguistic discipline. Bittel’s role was pivotal in translating the company’s foundational reserve into a consistent global posture. The tone remained discreet, but the message became more unified.

This was the period when the Calatrava ref. 3919 emerged as a symbol of the brand’s identity. Slim, classically proportioned, and paired with a white dial and hobnail bezel, it was chosen as the face of the first truly international Patek Philippe advertising campaign.

The accompanying ad was simple and its layout was spare: the watch placed against a white background, with a small block of copy. No actors, no props, no dramatisation. The tone conveyed confidence without affectation. In contrast to the heavily styled ads of the period, Patek’s imagery felt quiet and self-assured. As noted in Patek Philippe: The Authorized Biography, this campaign marked the first unified global articulation of the brand’s values through advertising.

This campaign marked the first time Patek Philippe presented a single voice across continents. American, European, and Asian markets received the same creative direction, reinforcing a global identity grounded in refinement and clarity. In parallel, the brand avoided endorsements, product placement, and personality-driven exposure. Value was expressed through coherence: the consistency of message, design, and form.

At the same time, the exhibition strategy launched in the United States decades earlier continued to mature. Patek Philippe began presenting archival materials, movement architecture, and rare timepieces in traveling formats. According to Patek Philippe in America, these exhibitions helped create a more intimate form of brand communication, where historical perspective gave depth to the present collection.

These exhibitions remained modest in scale, with a clear purpose: to create emotional proximity between collector and brand through depth of context. By presenting what came before, the company gave meaning to what was being produced in the present.

Warren Buffet holding the Caliber 89 during a private exhibition in 1995 . Image – Collectability

In 1995, a brief moment of unplanned publicity captured this alignment between brand philosophy and external perception. Warren Buffett, one of the world’s most prominent value investors, was photographed holding the white gold Calibre 89.

The caption read: “The six billion dollar man holds the six million dollar watch.” Though not part of any campaign, the image circulated widely. It reinforced the idea that ownership of a Patek Philippe represented a long-term view: one of value, of permanence, of time itself.

As the decade drew to a close, Patek Philippe stood apart in a field increasingly shaped by short-term messaging and visual noise. Its communication approach relied on restraint, editorial clarity, and a consistent alignment between product design and the words used to describe it. The foundation was in place for something more lasting.

The Generations Campaign and Emotional Language (1996–2005)

In the mid-1990s, the luxury watch industry was dominated by image-led campaigns built around celebrities, bold product photography, and status symbolism. Many brands framed ownership as personal reward or visual assertion. The language of advertising leaned heavily on ambition and lifestyle, especially in the American and Asian markets. Emotional storytelling, when used, was often secondary to product display.

Patek Philippe chose a different route. In 1996, following a strategic review led by Jasmina Steele, the brand’s longtime communications director, the brand parted ways with its longtime advertising partner and began searching for a new agency. The selection of London-based Leagas Delaney marked a decisive shift. The brief was clear: avoid spectacle, preserve meaning, and establish an identity that reflected values already embedded in the product itself. What followed was a complete rethinking of how a watch brand could speak.

“Begin your own tradition” 1996 ad campaign. Image – Patek Philippe

Consumer research revealed a consistent insight: high-net-worth individuals were disengaged by celebrity-driven messaging. When presented with endorsements, the question was often the same: “What about me?” Rather than aspire to someone else’s life, these clients wanted to see their own values reflected. They were seeking emotional connection, not vicarious identity.

Tim Delaney, the agency’s principal, distilled this into a new concept, “begin your own tradition”. The first advertisements featured no watch at all. Instead, they showed quiet, idealised moments between parents and children, a father and son, a mother and daughter, framed in soft light, their expressions captured with editorial intimacy. The product appeared only in a caption or as a separate inset. The focus rested on the relationship between generations, with the watch serving as its quiet marker. As Mr Delaney recalled in interviews, the goal was to speak to a sense of permanence and private meaning without theatricality.

The 1997 ad campaign. Image – Patek Philippe

In early 1997, the campaign introduced a line that would define the brand’s voice for decades to come:

“You never actually own a Patek Philippe. You merely look after it for the next generation.”

The message reframed luxury as stewardship. Ownership became a form of responsibility, and the watch a vessel of continuity, less a symbol of achievement than an expression of long-term connection. The campaign offered a gesture toward meaning, inviting buyers to see the purchase as part of a larger personal history.

Throughout this initial phase, the campaign remained visually consistent: natural light, muted color palettes, and understated styling. The watch was never worn in the main images. The emphasis stayed with the people, the moments, and the emotion they carried. As Patek Philippe: The Authorized Biography confirms, this shift in tone represented the most significant evolution in the brand’s communication since the early 20th century.

The campaign also avoided overexposure. Patek Philippe placed its ads in upscale publications with high reader loyalty, The New Yorker, Financial Times, The Economist, and titles that spoke to depth over volume. There was no rotation through seasonal slogans or novelty-driven copy. Each execution felt part of the same, continuous idea.

“Who will you be in the next 24 hours” ad campaign. Image – Patek Philippe

For women, the campaign developed its own branch beginning in 1999, coinciding with the launch of the Twenty-4 collection. These ads retained the core message but shifted tone slightly to reflect independence, modernity, and personal meaning outside the context of family. This branch of the campaign was one of the first in luxury watchmaking to speak directly to women without condescension or fashion framing.

What emerged in these years was a campaign that shaped the brand’s entire voice, capable of carrying new models, evolving in detail, and returning consistently to its foundation: a watch as a connection between people, across time.

Modernisation and Market Control (2006–2020)

As digital platforms reshaped communication and watch collecting entered a global resurgence, luxury advertising underwent another transformation. The 2000s and 2010s were defined by multimedia campaigns, video content, social media storytelling, and influencer partnerships. Many watch brands shifted toward immediacy, chasing relevance through collaborations, endorsements, and seasonal imagery aimed at younger audiences.

Patek Philippe continued on its own course, choosing to refine the structure of its existing campaign instead of adopting rapid content cycles. In 2006, a subtle but meaningful visual change was introduced: watches began appearing on wrists in the photographs. The first execution of this updated format was shot by Peter Lindbergh and featured the Nautilus ref. 5712. This marked the first time product and narrative were visually integrated. The emotion remained, and the context expanded. The product became part of the narrative frame.

2006 ad campaign featuring photography by Peter Lindbergh. Image – Patek Philippe

This visual update allowed the campaign to carry more product visibility while retaining its tone. The framing stayed consistent, natural light, candid composition, and the absence of theatrical styling. The hands in the photograph were still the primary subject; the watch was present, but never dominant. It became part of the gesture, secondary to the moment it helped express.

The messaging did not shift. The original tagline – “You never actually own a Patek Philippe” – remained unchanged. What evolved was the ability to communicate both intimacy and product simultaneously, without disturbing the balance.

The 2019 “The Art of Watches Grand Exhibition” in Singapore. Image – Patek Philippe

Beyond the campaign, Patek Philippe deepened its presence through educational and cultural initiatives. The company’s exhibitions, previously concentrated in boutique environments, scaled into major public events.

The Watch Art Watch Grand Exhibition took place in New York (2017), Singapore (2019), and Tokyo (2023) – and in Milan come 2026 – offered visitors an immersive experience in horological history, with archival pieces, watchmaking demonstrations, and thematic rooms recreating aspects of the manufacture.

According to Patek Philippe: The Authorized Biography, these exhibitions were conceived as brand showcases and as carefully designed encounters with continuity and craft. They served a dual purpose: to reinforce heritage and to create long-term emotional engagement.

At the same time, the Patek Philippe Museum in Geneva became a strategic asset. Visitors experienced the full arc of watchmaking, from 16th-century timepieces to the most complex creations of the modern era. This material presence offered an answer to the digital saturation around it. While others built stories for screens, Patek Philippe built rooms, displays, and timelines.

Entrance of the Patek Philippe Museum in Geneva. Image – Patek Philippe

In digital environments, the brand remained selective. Its website functioned less as a retail hub and more as a curated archive. Social media was handled with restraint, fewer posts, longer intervals, and no attempt to mimic trend-driven behavior. Tone across channels remained consistent: composed, focused, and grounded in continuity.

This period also reinforced a broader strategy: Patek Philippe tightened control over distribution, limited production, and emphasised the importance of family ownership. These choices, while operational in nature, shaped the narrative context of its communication. The story remained clear, this was a brand that moved at its own tempo.

By 2020, the “Generations” campaign had run for nearly 25 years. It remained visually recognisable, emotionally resonant, and commercially effective. No other luxury watch brand had maintained a single campaign for so long. And no other had positioned permanence itself as the product being offered.

Present and Ongoing (2021–2025)

The 2020s have introduced new dynamics in how luxury is communicated. Digital acceleration, collector communities, and rising transparency across markets have reshaped the landscape. Brands now operate across overlapping channels, where watches circulate in both physical and digital environments, and perception is shaped by rhythm, exposure, and narrative reach.

Patek Philippe continues to navigate this terrain with measured intent. Its campaign remains visually and verbally consistent, structured around the same format introduced in 1996. The tagline still appears in each execution, the imagery continues to depict quiet exchanges between generations, and the composition maintains its deliberate pace. The endurance of this approach reflects a conscious decision to preserve coherence in an increasingly fragmented media environment.

2025 ad campaign featuring the new Cubitus collection. Image – Patek Philippe

Recent advertisements have introduced broader casting and contemporary settings, reflecting cultural shifts while remaining grounded in the brand’s language. These adjustments occur gradually and with precision. This steadiness has become a signature trait, less about resisting change than shaping it slowly from within.

Public exhibitions and curated environments have also continued to evolve. These presentations blend archive, craft, and current production in settings designed to foster emotional alignment. In parallel, the company has refined the conditions under which its watches are encountered. Over the past two decades, Patek Philippe has concentrated its retail presence through a select network of boutiques and trusted partners. This strategy aligns setting with message, allowing each point of contact to reflect the brand’s principles of privacy, coherence, and long-term significance.

Boutiques are conceived as environments of intent. Materials, architecture, and spatial rhythm shape the encounter with care and clarity. The pace reflects the brand’s philosophy, time is approached with consideration and care. In a culture shaped by immediacy, this structure enhances the perception of rarity through rhythm, presence, and control.

Collage of Patek Philippe magazine covers. Images – Patek Philippe

At the collector level, engagement remains personal and curated. Relationships are maintained through private communication, tailored events, and long-standing editorial vehicles. Patek Philippe, the brand’s in-house magazine, was first published in 1996 and continues to offer a carefully controlled platform for storytelling, education, and cultural positioning. Conceived by Philippe Stern, the magazine supports the continuity of the brand’s voice and extends its narrative across generations.

The language of the campaign has seen gentle refinements. Captions now refer more directly to life events, weddings, graduations, family milestones, always in relation to memory and continuity. A watch is presented as a vessel of meaning, shaped by the experiences that surround it.

The “Generations” campaign is now approaching thirty years of continuous use. It carries the weight of the brand’s worldview across evolving demographics and expanding markets. Through this continuity, it has become one of the most enduring campaigns in contemporary luxury, a framework through which Patek Philippe continues to express value, identity, and time.

Conclusion

Patek Philippe’s marketing evolution traces a line of continuity that mirrors the way its public perceives its watches, precise, unhurried, and carefully maintained. Across changing eras, shifting media, and expanding markets, the brand has preserved a consistent approach to communication: clear in tone, restrained in style, and anchored in long-term thinking.

Each phase, from royal commissions and world exhibitions to generational messaging, has expressed the same idea through evolving forms. The brand defines value on its own terms, allowing meaning to grow through coherence and repetition.

Across poster art, editorial campaigns, curated exhibitions, and digital environments, Patek Philippe has remained steady in its messaging. It speaks through rhythm and structure, allowing perception to accumulate through alignment of image, language, and experience.

This clarity grows through consistency. Every decision in voice, format, and setting reinforces the product’s intended role, a possession shaped by purpose and framed with intent. Like its mechanical craft, the brand’s communication is designed to endure, holding its shape across generations.

Part I of our story on the evolution of hairspring materials covered temperature compensation along with the development of the first specialised balance spring alloy, Elinvar. The story brought us to the 1920s, when scientist and horologist Charles-Edouard Guillaume (1861-1938) finished his work on nickel-iron alloys and watchmakers begun embracing Elinvar springs paired with mono-metallic balances.

In this second part we turn to newer hairspring alloys, like the now-ubiquitous Nivarox. Then we look at today’s landscape and the future, touching on research done by the Swatch Group with alternative, niobium-based alloys and also the specialised but obscure Seiko SPRON 610 hairspring. Lastly we discuss silicon springs, which are growing more prevalent across a range of timepieces.

Elinvar’s weaknesses

Elinvar was by far the greatest breakthrough in self-compensating alloy hairsprings at the time. Guillaume considered Elinvar good enough and not needing further improvement — unsurprisingly since he was its inventor — but other watchmakers and engineers continued to experiment with iron-nickel compounds because Elinvar’s inherent properties made it a good, but imperfect, material.

Even though the alloy behaved predictably with temperature changes, its physical properties were not ideal to begin with. Elinvar was a soft metal, which posed its own suite of problems for spring applications.

The importance of softness in terms of hairspring performance is not related to outside interference, but instead linked to the internal molecular work and behaviour of iron-nickel alloys. As the hairspring vibrates, some energy is lost to internal friction due to the movement of molecules that make up the alloy.

The tourbillon regulator in the Daniels Grand Complication most probably uses an Elinvar spring. He was known to source new old-stock Hamilton springs, especially the 922 model.

While harmonic oscillator models, like a sprung balance, theoretically rely on a perfect potential-to-kinetic energy transformation, the reality is a little more complicated. A sprung balance is in fact a damped oscillator, which once started, tends to oscillate in increasingly smaller arcs, due to resistive forces of all kinds, until it stops when the energy has run out. This is why an escapement is required to force the balance to continue oscillating, restoring the lost energy at each impulse. 

One of the resistive forces is related to the internal molecular work of the spring, which absorbs potential energy. Compared to tempered steel springs, the iron-nickel exhibits a more pronounced molecular defect, which translates to an over-damped oscillator. This was first noticed first by watchmaker Paul Perret (1854-1904), a peer of Guillaume’s, in his early experiments with Invar-based springs.

Another inconvenience of iron-nickel alloys, apart from their inherent damping, is ferromagnetic behaviour. Although the springs themselves do not become magnetised, they are still attracted to magnetic fields. So a watch equipped with such a spring would run erratically in magnetic environments even if it wouldn’t remain magnetised.

However, this was considered a characteristic rather than a flaw at the time. The fact that regular timekeeping would resume after the removal of the magnetic field was considered satisfactory enough.

Dr. Straumann and the birth of Nivarox

Reinhard Straumann (1892-1967) was a Swiss engineer from Waldenburg in the canton of Basel who pursued practical watchmaking training but also earned an academic degree in mechanical engineering. 

Compared to Guillaume, Straumann was more in touch with actual watchmaking, having been a horological apprentice. After his studies concluded, Straumann joined Revue Thommen, a watch and instrument maker located in his native Waldenburg.

In the 1920s, Elinvar springs became widespread among many watch manufacturers and Straumann himself worked with them. He quickly became disappointed by the iron-nickel springs, which he discovered damped the oscillator too much and were susceptible to direct magnetic influence. Straumann also argued the soft metal was ultimately unsuitable for applications in smaller watches, due to its softness and deformability. 

While the engineer did not discard Elinvar completely, he felt it could be improved. Straumann even got in touch with Guillaume at some point to discuss the idea, but the latter didn’t show much interest.

Straumann didn’t let the matter rest, however, and looked outside horology for answers. A native of the German-speaking part of Switzerland, Straumann also had the advantage of easily communicating with engineers in neighbouring Germany — Waldenburg is today just a 30-minute drive away from the German border.

Straumann followed the latest developments in material science and metallurgy across the border, and became acquainted with beryllium alloys. A variety of companies added beryllium to metallic alloys to increase yield strength and Straumann believed adding traces of beryllium to Elinvar would solve the issue of softness. 

After early experimentation with some German companies, Straumann soon discovered adding beryllium to the iron-nickel concoction would in fact affect the thermoelastic behaviour of the resulting alloy. Subsequent experimentations with additional alloying materials such as chromium, molybdenum and tungsten proved very successful. Not only did these additional metals stabilise the thermoelastic behaviour of the beryllium-alloyed Elinvar, but it also made it easier to fine-tune the thermoelastic coefficient.

As Straumann describes in his patent filed in 1932, one could make the coefficient negative, positive, or null, just by adjusting the alloy mixture. The new alloy kept the quirky thermal proprieties of Elinvar, but with the added strength of beryllium.

Habring² movement with a Triovis regulator and modern Carl Haas hairspring

The early work on the new alloy springs was done by Straumann in conjunction with other German engineers and manufactured by Carl Haas, the German metal-wire specialist that today supplies hairsprings to Habring² amongst others.

These new springs contained 0.1-3.0% beryllium and a mix of chromium, molybdenum and tungsten that together amounted to 5-30% of the material, with the remainder being iron-nickel alloy. When rolled and heat tempered, the new springs were as stiff as hardened steel, did not over-damp the oscillator, and had a sensibly linear thermoplastic behaviour in the -50°C to +50°C range. 

Straumann’s observation about tailoring the thermoelastic coefficient to function was important, since the then-new monometallic, one-piece balance wheels still deformed slightly with temperature. Made from brass or German silver, the balance wheels would still affect the running rate with temperature changes — so having a tailor-made spring to counteract these effects was advantageous. 

The new material developed by Straumann and his collaborators was named Nivarox, a contraction of nicht variabel oxydfest — “non-variable [and] non-oxidising”. The name is slightly misleading since it doesn’t convey the full extent of the new material’s characteristics. Nivarox does not oxidise or rust (compared to Elinvar that was less oxidation-resistant), but it is also harder and stiffer. Nivarox was still susceptible to magnetic influence, but to a lesser extent compared to Elinvar.

Early Daniel Roth tourbillon, with a movement jointly developed with Lemania during his time at Breguet. Just like most timepieces of the era, it uses a Nivarox hairspring.

Straumann left Revue Thommen and founded Nivarox in 1934 in Saint-Imier. There he produced Nivarox hairsprings and worked on other metallurgy projects. In 1954 he set up the Dr. Ing. Reinhard Straumann Institute in Waldenburg, an entity separate from Nivarox that would carry out research and development work.

The institute was reorganised in 1990 and renamed Straumann, a firm that’s the world’s largest maker of dental implants. Straumann’s grandson, Thomas Straumann, is a billionaire thanks to the substantial stake in the company.

Notably, the younger Straumann bankrolled the establishment of H. Moser & Cie. in 2006, along with its sister company, hairspring maker Precision Engineering AG. The subsequent financial crisis forced Mr Straumann to sell his watchmaking investments, but Precision Engineering is today one of the leading suppliers of hairsprings to independent watch brands.

As for Nivarox, it is today the largest maker of hairsprings in Switzerland. In 1984, Nivarox merged with Le Locle-based les Fabriques d’Assortiments Réunies (FAR), the result of a 1932 combination of various small producers of escapement parts.  This gave birth to Nivarox-FAR, which was eventually acquired by today’s Swatch Group but left to operate under its original name. Nivarox is now the prevalent material for hairsprings, with its maker the biggest supplier of them.

For a long time, Nivarox seemed to be the final chapter in the long evolution of hairspring alloys. 

A Precision Engineering hairspring inside a Moser movement 

Nivachron

Nivarox-FAR remains a key company of the Swatch Group, delivering hairsprings and escapement parts to all the companies owned by the conglomerate, ranging from Omega to Longines. Nivarox-FAR was also instrumental in adapting George Daniels’ Co-axial escapement for mass production. While the first Omega Co-axial movements were made in ETA facilities, the escapement parts were supplied by Nivarox-FAR. 

Its parent allowed Nivarox-FAR a fairly large degree of freedom in terms of research. One of Nivarox-FAR’s more successful exploits in hairspring metallurgy came about in 2018 when the laboratory announced a new hairspring material, Nivachron, developed in collaboration with Audemars Piguet.

Nivachron hairspring in a Sistem51 movement.

Nivachron promised 10-20 times more magnetism resistance compared to Nivarox, not to greater shock resistance while maintaining the same thermal insensitivity. The name itself was odd, with “Nivachron” possibly being a word play on “Nivarox” and “chronometric”.

The new material was described as a “titanium-based alloy”, which upon further inspection of patents filed looks to be a titanium-niobium alloy. Patents for the material filed between 2017 and 2018 point to a bi-phased composition of 45-48% titanium and a balanced remainder of niobium. The patents suggest traces of other elements may be found, but in any case under 0.3%.

Notably, the use of niobium in hairsprings goes much further back, to the early 2000s with the Rolex Parachrom hairspring, an alloy of niobium and zirconium. 

A Nivachron hairspring installed in a Tissot movement (that is in turn derived from the Valjoux 7750)

In metallurgy, a bi-phased composition has the components present in different microstructures at a given state (temperature, composition ratio). For Nivachron, a binary alloy, the two constituents appear in different crystal conformations, namely body-centred cubic for niobium and compact hexagonal for titanium.  

The result is an interesting alloy that in certain compositions exhibits Elinvar-like thermoelastic behaviour. Moreover, niobium-titanium alloys have high magnetic resistance, making them far superior to classic Nivarox in that respect.

Swatch Group also explains that Nivachron hairsprings are stronger, as the alloy has a higher yield strength than Nivarox, but it doesn’t seem that characteristic makes much of a practical difference in horological applications. When a mechanical watch is subjected to strong shocks, either the balance pivots or the escapement will break before the hairspring deforms, so the wearer does not necessarily profit from a stronger hairspring. 

A Blued Nivachron hairspring

At its launch, Nivachron was touted as the next big step forward in mass-produced hairsprings, but it slowly faded over the years. Nivachron springs were installed in Swatch System51 movements and in some Tissot and Certina models, but it was clear the Swatch Group was moving away from alloy springs and into silicon manufacturing. As it turned out, the alloy was not as revolutionary as it seemed to be at its debut.

Earlier this year Breguet presented the Classique Souscription, which features a blued Nivachron spring. Here the blue hue looks like the result of classic heat tempering, unlike the more artificial colour treatment of Rolex Parachrom. Other than the latest Breguet, the Swatch Group has mostly kept quiet about its use of Nivachron springs, with even less heard about it from Audemars Piguet. 

The Japanese connection

The Japanese watchmaker Seiko also had a lot to gain from the research on hairspring alloys carried out in Switzerland. As Nivarox became the standard, Seiko made their own alterations to Elinvar and experimented with adding cobalt to the mix. 

Little is known about the exact contents of the cobalt-Elinvar alloy Seiko used for a long time, but it was reliable enough that the watchmaker employed such springs for more than 50 years. Then, in the early 2000s, Seiko went about further perfecting its hairsprings, which the brand did in collaboration with Tohoku University. 

In 2009 SPRON 610 hairsprings were launched. The new in-house springs were manufactured entirely by Seiko, or more accurately one of the companies in the vast Seiko Group, from ingot to wire, but were reserved for the more exclusive Grand Seiko timepieces. 

Again, the exact composition of SPRON 610 remains elusive. It looks to be an optimisation of the cobalt-enriched Elinvar, making SPRON an alloy of cobalt-nickel-iron. Seiko claims a high magnetic resistance (higher than basic Elinvar in any case) and a high tensile strength. 

The addition of cobalt should have a similar effect that the addition of beryllium had on Elinvar in making Nivarox. Namely, SPRON must be a hard and resistant alloy, both to mechanical strain but also to corrosion. Just like Nivarox preserved Elinvar’s thermoelastic proprieties, so should in theory SPRON. 

Cobalt-nickel alloys are generally given aerospace uses, with them exhibiting excellent durability and fatigue resistance. Assuming that these qualities were preserved for cobalt-nickel-iron alloys, SPRON should be a very suitable material for hairsprings, with similar proprieties to Nivarox. 

While Seiko is secretive about the exact nature of their SPRON alloys and how performant their springs are, newer Grand Seiko models are adjusted to a -3/+5 seconds per day deviation, two seconds tighter than the C.O.S.C. tolerance of -4/+6 seconds a day. This suggests the hairsprings are chronometrically-potent and on par with those in modern Swiss precision timepieces. 

The silicon route

Apart from the more recent Nivachron venture from the Swatch Group, the most intensive research into hairspring materials was done in the early 2000s. Rolex with its Parachrom, Seiko with SPRON 610, and a consortium of brands working on alternative silicon oscillators. 

As explained in our past article, Ulysse Nardin Freak: The Saga of a Scientific Timepiece, Part III, the first watchmaker to experiment with silicon hairsprings was none other than Dr Ludwig Oechslin with his work for Ulysse Nardin. The Ulysse Nardin Freak became the first-ever watch with a silicon escapement when it was launched in 2001. Soon after, CSEM reached out to Dr Oechslin in order to inquire whether silicon could be applied to other movement parts as well. 

The first silicon hairspring. Image – ‘Silicon and Watchmaking, report of trials with silicon hairsprings at the Musee International d’Horlogerie’ by Dr Ludwig Oechslin, MIH

Dr Oechslin thought of hairsprings as an ideal application, exploiting silicon’s elastic capability and even built the first prototypes in collaboration with CSEM. By installing raw silicon hairspring prototypes into simple Unitas movements, Dr Oechslin reported a 106-second daily error over a temperature variation range of 31°C.

Unitas movement equipped with an experimental silicon hairspring. Image – ‘Silicon and Watchmaking, report of trials with silicon hairsprings at the Musee International d’Horlogerie’ by Dr Ludwig Oechslin, MIH

In its pure state, silicon exhibits a strong variation of Young’s modulus with temperature, meaning the springs’ elasticity was dependent on temperature changes. While diamagnetic (impervious to magnetic influence) and fatigue-resistant, silicon springs seemed to suffer from the same issue as the earliest iron hairsprings: no temperature compensation. 

The gross daily deviation of the prototype silicon springs was due to silicon’s negative thermoelastic coefficient, which softens the spring at higher temperatures, making the movements run noticeably slower.

Silicon hairspring in the Breitling-derived Tudor MT5813 movement.

The solution to this issue was found shortly, and was surprisingly straightforward: a coating was required for the pure silicon core spring. A suitable coating an oxide of silicon itself, SiO₂, which has an advantageous opposite thermoelastic coefficient value to that of pure silicon. 

The proposed SiO₂ coating has a positive thermoelastic coefficient, which means the coating becomes more rigid at higher temperatures. Since in the direction of spring deformation there are two layers of SiO₂ coating bounding the pure silicon core, the resulting hairspring, when engineered correctly, has a near-zero thermoelastic coefficient. 

The oxide coating has about 6% of the silicon core’s thickness, meaning it does not affect the overall hairspring dimensions. Compared to alloy springs which are rolled, coiled and heat treated, the silicon springs are etched from a large wafer and thus don’t suffer from eventual molecular shifts. 

Syloxi hairspring, Rolex’ own take on the silicon spring

The result of coating silicon with silicon dioxide was christened as silicium, a material that was the subject of the original patent regarding silicon hairsprings: patent EP1422436B1 filed in 2002 concerned a silicon hairspring that was self-compensating for temperature changes, without mandating any specific spring shape.

The research into silicium was backed by CSEM, Rolex, Patek Philippe, Swatch Group, and Ulysse Nardin, allowing those brands exclusively to manufacture silicon springs under the patent guidelines, but each implemented its own coil geometries. The patent has expired in 2022, leaving the for open for other companies to explore silicon manufacturing. 

The adoption of silicon has been widespread and it is more than likely that several million mechanical watches with silicon-equipped movements have been sold since the material made its debut.

That said, silicon is not the perfect material. Silicon is not isomorphous, so its elasticity depends on the molecules’ orientation — which is to say it is advantageously elastic in the coils’ radial direction, but not so much when strained in other directions. In practice, this means silicon hairsprings need more care when the movements are either put together or serviced, since the coils can be rather brittle when pulled vertically.

Closing thoughts

This two-part story on the evolution of hairspring materials in mechanical watches was meant to be an overview of the landmark advancements in spring compositions since its invention 350 years ago. The account covered to an extent both the historical and scientific aspects of the important steps watchmakers and engineers took towards more accurate mechanical timekeepers.

The story intentionally overlooked some smaller-scale advancements, like TAG Heuer’s prototype carbon-composite high-frequency hairspring or the recent mono-block silicon oscillators. The story didn’t explore specific hairspring coatings or boutique manufacturers (like Precision Engineering and its PE 5000 alloy) but rather focused on those inventions which were truly revolutionary, reaching mass production and acceptance across a large range of timepieces. 

MB&F movement with a PE 5000 alloy hairspring supplied by Precision Engineering AG.

First came Invar, which paved the way for specialised spring alloys. Elinvar followed, with the first truly temperature-impervious hairsprings. Nivarox closed the chapter, with the most widespread use across millions of modern timepieces. 

Other notable advancements, like the rather obscure SPRON 610 from Seiko or Swatch Group’s own Nivachron speak of the modern metallurgy and research capabilities of large brands, although their development is not as groundbreaking as the Invar family of alloys. 

Finally the use of silicon parts in timepieces is perhaps the most interesting and laudable feat of 21^st century watchmaking. Silicon hairsprings have been more and more prevalent lately, although classic brands tend to steer clear of them. The latest micro-mechanical developments also point to a rise in mono-block high frequency oscillators, so the 350 year old hairspring might be soon overtaken by events. 

In the world of independent watchmaking, Phimphrachanh – pronounced “fin-fra-chan” – is a name worth learning. Born in France, Dann Phimphrachanh is a Portuguese citizen with Laotian heritage who produces watches in Switzerland. That multicultural heritage that informs his approach to horology, personified by the Seconde Vive, his first wristwatch.

The Phimphrachanh surname, inherited from his Laotian grandfather, a political figure in Laos, speaks to this lineage, but Dann’s professional and personal identity is firmly rooted in Portugal. After training in Lisbon’s watchmaking school and working at traditional Swiss watch brands, Dann set out to build his first watch on his own terms: by hand, with minimal industrial tools, and a commitment to preserving classical methods in a modern context.

In a world where “independent watchmaking” can sometimes feel like just another label, Dann reminds us what it really means. The Seconde Vive, the result of years of solitary work, is both a technical achievement and a reflection of a deeper pursuit, a journey shaped by tradition, silence, and the slow mastery of time itself.

The Seconde Vive

Origins

When Dann first left for Switzerland, he carried with him an image shaped by the glossy pages of watchmaking magazines, a world where the watchmaker was portrayed as a solitary figure, pursuing perfection in a quiet, idyllic workshop. “It was that image I went looking for,” he recalls.

Reality, of course, was more complex. Although he was warmly welcomed into a family-run brand that remains close to his heart, the deeper he moved into the world of Swiss horology, the more he encountered quiet disillusionment. The romantic ideal he had built from afar did not always survive contact with the modern realities inside the great houses. Some traditions endured; others had worn thin.

Yet Dann’s commitment remained firm. When asked whether he sees himself as an heir to tradition or a pioneer forging a new path, he answers without hesitation. For him, being a watchmaker means standing humbly on the achievements of those who came before.

“Watchmaking isn’t just a passion,” he says. “It’s also work that demands effort, study, and the right tools.” His personal aim is clear. He doesn’t want to reinvent for the sake of novelty, but to inhabit horology fully, carrying its spirit forward with admiration and conviction.

Process, Solitude, and Self-Discovery

Since 2018, Dann has worked almost entirely alone, a choice that has profoundly shaped his approach. Solitude, far from being a burden, became an ally. It taught him not only the real timescales of creation but also the value of allowing ideas to evolve without external pressure.

“Solitude is a wonderful place when you believe in what you’re doing,” he says, “Every step becomes human, and the journey matters as much as the destination.”

Study for main-plate. Image – Dann Phimphrachanh

Isolation forced him to rethink everything, from how he structured his atelier to how he prepared himself mentally for the rigours of creation. School, he acknowledges, provided the essential technical foundations. But solitude became his truest teacher.

In his daily work, writing has become an indispensable ritual. Before and after each complex operation, he takes the time to write, a way of channelling the intellect and preserving joy in the process. Different phases of watchmaking demand different mental postures. When designing mechanisms or calculating gear ratios, he engages his intellect fully. But when sketching freehand or filing bridges, he deliberately quiets the analytical mind, allowing instinct to take over. Writing acts as a bridge between these contrasting states, a thread of coherence in a demanding craft.

The Architecture of the Seconde Vive

Describing the movement of the Seconde Vive isn’t easy, even for its creator. Dann didn’t begin with strict aesthetic rules; instead, he let instinct and handwork guide the forms, aiming for a feeling of depth, a movement that fills its space with natural balance.

Technical needs like working angles and clearances shaped the calculations behind it, but visually, the structure grew on its own terms. As he puts it, “I had no intention in the forms, my only goal was to feel a sense of depth and to have a movement that filled the case.”

Planning components. Image – Dann Phimphrachanh

At the heart of the watch lies the Seconde Vive, a complication born from both personal need and creative drive. Dann sought to assert his legitimacy as a watchmaker, to show through mechanical function, not style alone, that he belonged among the craft’s true practitioners.

As a graduate of the Lisbon watchmaking school who arrived in Switzerland with a sense of impostor syndrome, creating a visible, animated mechanism was a way of claiming space through craft. At the same time, he wanted to create something anyone could understand: an animation slow enough for the eye to follow, yet lively enough to hold attention.

Working on a minute pivot. Image – Dann Phimphrachanh

Seconde Vive, translating as “lively seconds,” reflects this intent. The hand jumps visibly, but the mechanism is not a pure deadbeat seconds system. Instead, the Seconde Vive celebrates motion for its own sake, offering a mechanical rhythm that feels alive, immediate, and engaging, without necessarily serving a chronometric function.

It is, as Dann puts it, “a horological wink”, a mechanical delight built for its own sake. The gear train and escapement visible on the dial side are entirely independent from the main timekeeping gear train, which quietly reveals itself on the reverse.

The seconds anchor that will engage the Reuleaux cam. Image – Dann Phimphrachanh

Technically, the seconds mechanism multiplies the motion of the minute hand by a factor of ten, then uses a triangular cam, inspired by the geometry of the Reuleaux triangle, to generate 30 steps per minute. This is then doubled with a custom anchor to achieve 60 discrete jumps per minute. It was a solution chosen not only for its rhythm but because the motion could be perceived and appreciated by anyone, regardless of horological training.

Part of this technical exploration led Dann to the geometric principles of the Reuleaux triangle, a shape known for maintaining constant width during rotation, a property that allows for highly controlled and consistent motion. In engineering, the Reuleaux triangle has been used in applications from rotary engines to precise cam systems, and although rarely seen in traditional watchmaking, its potential for managing torque and minimising friction intrigued Dann.

He saw in it a mechanical language that paralleled his own aims for the Seconde Vive: to create a visible, lively motion that felt smooth, rhythmic, and naturally coherent within the watch’s architecture. His thinking echoes the spirit of Derek Pratt, who drew inspiration from rotary geometries like the Wankel engine when developing his own escapements, seeking not just precision, but elegant mechanical efficiency.

Lathe work in the atelier. Image – Dann Phimphrachanh

Bringing the Seconde Vive to life also meant facing the practical realities of independent work. Although Dann machines all the mechanical components himself, he chose to rely on commercially available barrel springs and balance springs, a decision born from pragmatism rather than compromise. Manufacturing these components is viable only at industrial scales, and sourcing them ensures that the watch remains serviceable for generations to come.

Budget constraints, too, shaped his approach. Every tool and machine in his workshop had to be chosen carefully, often requiring restoration rather than replacement.

“Living time with passion,” he says, became the philosophy: working slowly, intentionally, as artisans once did, with an intimate knowledge of every machine’s temperament. This spirit of resourceful independence is deeply embedded in the Seconde Vive itself, not merely in its aesthetics or mechanics, but in the choices that made its existence possible.

Finishing tools. Image – Dann Phimphrachanh

Friction, as always, proved the greatest adversary. Every surface, pivot, and gear had to be painstakingly finished to minimise energy loss without compromising durability. Over time, by mastering the nuances of his own machinery, Dann learned to machine consistently within tolerances of five microns, a precision made possible by modern methods, but pursued with the patience and hand-focused spirit of the early masters he admires.

Material choices followed the same philosophy of longevity and repairability. He chose maillechort, or German silver, for the plates and bridges, hardened S20AP steel for structural parts, and silvered steel for the springs, all left untreated to preserve their ability to be refinished or repaired generations from now. The case itself was crafted in durable 316L stainless steel, completing the ensemble.

Spiral before applying terminal curves. Image – Dann Phimphrachanh

When the Seconde Vive finally came to life for the first time, it was far from the triumphant moment he had imagined. “Honestly, the first time it ran, it was a huge disappointment,” he admits. The seconds hand hesitated instead of snapping cleanly forward, the system consumed too much energy, and the overall design fell short of his hopes. It took four radical reworkings, including three successive reductions in pivot size and dozens of subtle refinements, before the movement reached the fluidity he had envisioned.

Fittingly, the true moment of satisfaction came not in the workshop, but on the forest trails and sidewalks of his town near Yverdon-les-Bains, where he tested two prototypes while riding his bicycle. Seeing both mechanisms survive real-world vibrations, ticking, jumping, alive, finally brought the project full circle.

When asked whether access to CNC or EDM machines would have changed his process, Dann simply shrugs: “If I had wanted to work with CNC machines,” he says, “maybe I wouldn’t have chosen watchmaking.”

Beyond the Seconde Vive

Fresh from the completion, and the first public presentation, of his debut creation as a candidate at the AHCI exhibition in Geneva, where the Seconde Vive was met with great success and a promising order book, Dann’s mind is already turning to quieter challenges.

Rather than rushing into new projects or chasing attention, his focus remains on laying solid foundations: creating a workshop environment that will safeguard his commitment to traditional, hand-crafted watchmaking.

“My concerns today are about creating the right conditions to guarantee my loyalty to traditional watchmaking and handcraft,” he says. “One step at a time. I don’t want to spread myself thin.”

Looking ahead, he feels naturally drawn toward the idea of developing new complications, though he recognises that true creativity resists rigid planning. “If the Seconde Vive taught me anything,” he reflects, “it’s that it’s impossible to predict the details. But I’m looking forward to the day the first drawings of the next piece appear”. 

The Future of Artisan Watchmaking

As more and more independent watchmakers emerge, Dann remains clear-eyed about the dangers of marketing co-opting the word “independent.” “If it’s not already the case, marketing will use ‘independent’ as a banner for as long as it remains profitable,” he says with a wry smile. “That’s the nature of marketing.” Yet he trusts that true connoisseurs, those who seek authenticity, will see beyond the labels.

Polishing of a ruby chaton. Image – Dann Phimphrachanh

For Dann, the spirit of independence is essential. Looking at the history of horology, he notes that even the most iconic creations from the great watchmakers bear the unmistakable mark of a single creator’s vision, not the efforts of an anonymous department. “Independent watchmakers today have created more true DNA, more real style, than millions spent in design departments over the past fifty years,” he reflects.

Guilloché decoration work on the dial. Image – Dann Phimphrachanh

What he hopes to see in the future is simple: more watches that are profoundly personal. “Watchmaking is like dance,” he says. “It’s all about DNA, about style.” If a creation can marry technical mastery, cultural richness, and personal expression, Dann is ready to be won over.

For now, Dann’s focus remains firmly on building his own path. Solitude, he knows, is not an easy companion, but it is essential to the way he works. “Maybe someday,” he muses, when asked whether he might one day share his methods. For the moment, though, creation demands all his attention: a quiet dialogue between hand, mind, and time, far from the noise of the world.

Time as the Final Lesson

Of all the lessons Dann drew from creating the Seconde Vive, one stands above the rest: the unpredictable nature of time. Not time measured in seconds and hours, but the lived experience of creative time, the slow accumulation of thought, the sudden flashes of intuition, the long, patient work of making and remaking.

Sometimes, despite all calculations, a perfectly crafted part would feel out of place. At other times, a less meticulously finished piece would prove to be the truest fit. He learned to let the work speak for itself, trusting his morning reflections, when the light was clear and the mind sharper, to guide his final decisions. “It was each morning, in that one clear moment,” he says, “that I knew whether what I was doing truly resembled me.”

In the end, the Seconde Vive was not shaped solely by the techniques Dann had acquired during nearly two decades in haute horlogerie, working at firms such as Daniel Roth, in the complications department at Bulgari, at Parmigiani Fleurier, Greubel Forsey, and Jaeger-LeCoultre. It grew from something quieter and harder to measure: the ability to listen, to doubt, to wait, and to live the time it takes to create something that feels alive.

Breguet will very likely close its 250th anniversary this year with a bang: launching a 21st century Sympathique as a tribute to perhaps Abraham-Louis Breguet’s greatest invention, a clock that could autonomously wind, correct, and regulate a removable watch.

While the brand has released no details, and there haven’t been any leaks, a series of patents gives us a peek at the new Sympathique. Notably, the patent drawings illustrate two possible companion watches: a 60 m water resistant Marine tourbillon and a Tradition. The latter is more interesting as it uses a novel form of Breguet’s échappement naturel, or natural escapement.

We explain both the new Sympathique 2025 and the natural escapement using information gleaned from Breguet’s patents.

Breguet Sympathique No. 1 by Francois-Paul Journe

Initial Thoughts

Three of the most historied names in the watch industry are celebrating anniversaries this year. Vacheron Constantin marked the occasion with Solaria, the most complicated wristwatch to date, while Audemars Piguet introduced an all-new Royal Oak Perpetual Calendar (and promises more to come in the fall).

In comparison, Breguet has debuted the Classique Souscription and Tourbillon Sidéral so far, both of which are objectively good watches but feel underwhelming in technical terms. A new Sympathique, on the other hand, would be the ideal centrepiece for the brand’s anniversary collection, being visually impressive, an icon of the brand, and entirely unique in the current market.

A drawing from Breguet’s Swiss patent CH717698A1

Of all A.-L. Breguet’s creations, the Sympathique was the most ambitious. The principle of the Sympathique was a simple one: the wearer would install his watch into the clock at night, and while he slept, the clock would wind, set, and regulate the watch, making it ready for use the next day. The execution of the concept, however, was exceptionally difficult and complex.

A.-L. Breguet’s firm on managed to deliver only eight Sympathique clocks during his lifetime, and not all with companion watches – the company completed five times as many tourbillions in the same period. Today, by combining the Sympathique with a natural escapement (another idea A.-L. Breguet struggled to realise during his lifetime), the modern-day Breguet firm is symbolically completing the master’s great unfinished works.

A key figure in realising the modern-day Sympathique clock is Alain Zaugg, the longtime head of Breguet’s technical development department who retired in 2021; his name is on all the related patents.

The small-correction approach

Historical Sympathique clocks cannot perform large time corrections, instead these clocks can only maintain a running watch by moving the time a short distance to the current time, and are unable to set a stopped or wildly inaccurate watch from scratch.

This small-correction approach is a limitation, but makes autonomous regulation possible, as a pair of pawls attached to the minute hand adjust the rate proportionate to distance and direction of the correction. A Sympathique corrects a very fast watch by moving the time significantly backwards, which simultaneously retards the rate substantially, and when correcting a slightly slow watch by adjusting the time forward, it will slightly advance the rate.

Setting and regulating of watch No. 2787 associated with clock No. 430 (page 352). Image – The Art of Breguet

Sympathique no. 128, made for the Duc d’Orléans and the most valuable Sympathique clock ever made, is very different. Rather than making minor corrections at regular intervals, the watch is automatically set to three 0’clock at that time in the morning.

This approach precludes automatic regulation, but as George Daniels (who restored the clock and watch) points out in The Art of Breguet, regulation isn’t needed “[as] this is a precision watch the parent clock does not move the regulator, as was done with the earlier type of Sympathique watch, which had no temperature compensation”.

Perhaps the most storied historical Sympathique, the example made for the Duc d’Orleans in 1835. Image – Sotheby’s

While the modern Sympathique has the same goals as those built under A.-L. Breguet, it goes about it entirely differently, resulting in it being the most polished and capable such clock yet.

The modern-day Sympathique illustrated in the patents goes even further, first resetting the watch and then adjusting it to match the current time. The innovations fix some of the shortcomings of its historical counterpart: the clock will probably be able to set the time automatically or on demand, and the automatic setting interval will probably be adjustable (and even disabled at will), though details on those functions are still hazy.

The new system shifts most of the time setting equipment to the clock – reminiscent of Louis Raby’s approach in Sympathique no. 5 – leaving the accompanying watch more similar to a chronograph controlled by the clock than anything else. The clock is essentially a trip-repeater set to trigger at a predetermined time, not unlike the alarm in Patek Philippe’s Grandmaster Chime.

The patent drawings depict the clock with a tourbillon, possibly a reference to A.-L. Breguet’s tourbillon carriage clock no. 780. If the drawings accurately represent the final product, the new Sympathique be a contemporary design entirely unlike any before, which is welcome. I hope there will be as much design diversity at Breguet in the future as in the past. Ideally that diversity would include an ecosystem of inter-compatible Sympathique clocks and watches.

Sympathique No. 5 made by Louis Raby in collaboration with Breguet. Image – Museum of Islamic Art, Jerusalem

The control mechanism

The wristwatch sits inside a cradle at the very top of the clock, as is convention for the Sympathique. While the patent drawings show the watch without a strap for clarity, the strap doesn’t need to be removed, unlike the small run of Sympathique clocks made by Breguet made in the 1990s that were developed by Francois-Paul Journe and then produced by Techniques Horlogères Appliquées (THA).

Within the cradle, the clock winds the wristwatch through its crown, and sets the time using a pair of actuators, similar to a stylus used to correct the date on a perpetual calendar.

Image – EP4202575B1

A counter-clockwise rotating cam (yellow) is locked by a lever (magenta). During time setting this lever releases the cam, which turns, pushing the first actuator (orange) all the way in to the first position, which stops the watch and resets the hands to 12:00:00. The watch remains stopped when the actuator drops out halfway into a second position, where the cam is locked by a second lever (black) allowing a second actuator (purple) to set the time.

Image – EP4202575B1

Since time setting is not instantaneous, the clock sets the watch slightly into the future, such as the next five-minute increment. Once the clock reaches that time, the second lever (black) unlocks the cam (yellow) which finishes a full 360° rotation, causing the first actuator (orange) to retract and the watch starts with the correct time.

Time setting

Now, we are going to go through the process again, but from inside the watch. A heart-shaped cam (brown) on the hour wheel and hammer (teal) reset the hours and minutes to 12:00, just like the reset of a chronograph. A vertical clutch (pincers in light blue) disconnects the hands from the rest of the movement just before reset. This means the reset and setting systems won’t need to fight friction from the canon pinion. The first actuator controls all these actions by moving the control lever (red).

When the first actuator (orange) pulls back halfway, into the second position, the control lever (red) pushes the motion-works hammer away while the combined seconds reset hammer and hacking lever (purple) stay in place, and a lightly tensioned jumper spring (pink) holds the motion works steady. Then the yellow control cam is locked in place, and time setting begins.

Image – EP4202575B1

The second actuator controls a jumper (blue). Each step advances the time forward by five-minute increments, similar to how the hour hand jumps in some travel time watches. Since this is done in discrete steps, static friction would again be an issue if not for that vertical clutch.

Image – EP4202575B1

(To explain time setting, I’ve used a simplified drawing from a related patent. A rack and snail-cam system reads the clock’s time and then transmits it to the watch. This is the same mechanism used by chiming clocks and repeaters. Another, more complex implementation – not covered here – uses two small snail cams rather than one large snail cam. In this implementation, if a 15-minute time setting resolution is acceptable, the clock could use the same cams for a grande ou petite sonnerie or quarter repeater to set the watch.)

In this case, a single massive cam – which rotates once in 12-hours – is divided into 144 steps, with each step representing five minutes. The rack (dark grey) falls onto the snail (gold) and is pulled back to its starting position. This passes through a differential (dark teal), and a shaft (magenta) transmits this motion to a four-pointed star (lime), which pushes the second actuator to advance the time.

Image – CH717698A1

The further the rack falls, the more times the second actuator is pushed, with the highest point on the cam being zero actuations (12:00) and the lowest point being 143 actuations (11:55). Naturally, a similar system could set a date on the watch from a perpetual calendar on the clock, which is also claimed in the patent.

A New Escapement

Similar to the Rolex Dynapulse or Ulysse Nardin Dual Ulysse escapement, the two escape wheels are geared together on a single level using specially designed toothing – while not explicitly claimed in the patent, the escape wheels will almost certainly be silicon. However, unlike the Rolex and Ulysse Nardin escapements that use an intermediate lever, this is a true natural escapement with direct impulse, as the escape wheels directly impulse the balance.

Image – EP4053643B1

In theory, energy transfer should be more efficient in a natural escapement than in escapements using an intermediate lever. There is also very little sliding action, reducing friction to a minimum.

The balance carries a pin which pivots an anchor back and forth, locking and unlocking the escapement, similar to a lever escapement. The locking lever sits on the same plane as the escape wheels, as opposed to above as seen in those made by A.-L. Breguet, likely reducing the system’s height.

Image – EP4053643B1

This would be Breguet’s first foray into alternative escapement designs since its experimental detent escapement that debuted in 2005 but never made it to market – a reminder that patented inventions are not always viable for commercialisation. That said, I believe this time will be different, and we will finally see a fully realised Sympathique closer to the end of the year when Breguet’s 250th anniversary celebration reaches its high point.

The invention of the hairspring was among the greatest breakthroughs in horology, since its inception suddenly made mechanical timepieces portable, transforming clocks into watches. This not only marked the start of precision timekeeping, but also set mankind upon the long road to perfecting the accuracy of mechanical watches, arguably the most sophisticated pieces of kit on Earth at the time, when such precision was paramount for fields as varied as navigation, warfare, and astronomy.

The hairspring turned 350 years old in 2025 and we’re marking the occasion with a series of stories on the topic, including the story of the spiral hairspring and also the importance and evolution of the overcoil. Now we turn to temperature compensation and metallurgy in a two-part story covering the evolution of the hairspring materials up until metal alloys. More exotic materials and inventions will follow in Part II.

Elasticity and thermal expandability 

One of the fundamental factors in hairspring function is ambient temperature, simply because metal alloys expand or contract uni-directionally with a change in temperature. As a result, watchmakers used calorimetry, the science of temperature effects, and material science, specifically metal alloys, to their gain in advancing hairspring technology.

The equation below shows the relation between the initial length of a metal strip L₀, measured at a given temperature and the final length L_T after a certain change in temperature. 

The equation is often reduced to the first linear term (containing the α coefficient), since it suffices for small changes in temperature and instances where extreme accuracy is not needed.

This is not the case for sensitive instruments like hairsprings, so the quadratic correction term (with β coefficient and squared temperature change) is required. The full equation with the quadratic correction term has long troubled watchmakers when compensating for temperature.

While this equation does not hold exactly true for the Young’s modulus’ change with temperature, it offers a good understanding of the non-linear changes in the temperature-related behaviour of metals (an important observation, as we’ll see later).

Temperature’s effect on metal elasticity is generally the same: temperature increases result in the agitation of atoms within the metal, leading to bonds between molecules slackening to a degree — making for a change in volume on a macro-scale. The weakened bonds also mean the molecules don’t attract each other with the initial strength and the material as a whole becomes suddenly less rigid.

For springs, this means the stiffness constant, a function of Young’s modulus, declines. This directly influences the frequency of the spring oscillator. We discussed the exact relation between spring stiffness, balance inertia and oscillating frequency in a past story concerning mechanical watch regulation. 

The takeaway here is that a rise in temperature not only causes metals to expand, but also makes them less rigid. This is intuitive, since a continuously heated metal sample will become softer and softer, until a phase change will occur and the material will become molten.

The earliest hairsprings

When Dutch astronomer and inventor Christiaan Huygens (1629-1695) first presented his sprung oscillator, he described the balance spring as “an iron spiral”. While “iron” was probably an iron-copper or soft steel alloy, the material was rudimentary and initially chosen for its malleability and elastic behaviour, which fitted Huygens’ needs at the time. The first embodiments of the system featured simple wire coils and had one and a half to two turns.

As the spiral hairspring slowly became widespread, watch and clockmakers noticed the material of the spring was perhaps as important as its shape. They discovered that steel alloys (steel is a mixture of iron and chromium) were rather susceptible to both temperature changes and also to atmospheric humidity, which tends to unevenly oxidise the iron component. 

Over time watchmakers experimented with different types of steel alloys, mostly carbon steel. While more stable compared to the first rudimentary springs, the steel was still very sensible to temperature changes. Moreover, watchmakers discovered a new phenomenon, the gradual weakening of ordinary steel springs due to the molecules shifting and the general fatigue of the material. 

For untempered steels, molecules dislodged during the plastic deformations involved in the manufacturing process (mainly cutting, rolling, and flattening in the case of balance springs) tend to diffuse into the material over time. This can unevenly stiffen the spring. We have covered the topic in more detail with Rolex blue Parachrom hairsprings.

Another longterm effect, larger in magnitude than molecular shift, is the fatigue. Fatigue is a metric tied to the repeated stress cycles a given part is subjected to over a specific time period. As a component of any sort is subjected to cyclic loading and unloading, it develops small cracks and plastic deformations over time, which change its structure and stiffness. 

In the case of a high-frequency vibrating spring which charges and discharges a number times a second, the fatigue is exacerbated and it doesn’t take long for the hairspring to lose its initial stiffness and become weaker. As with the weakness induced by the temperature changes, the frequency of the oscillator falls behind, effectively making the timepiece run slower. 

The eminent English clockmaker and a champion of precision timekeeping, John Harrison (1693-1776) was among the first to heat temper and harden the steel hairsprings, according to R. T. Gould’s The Marine Chronometer: Its History and Development. The heat-hardening slowed the springs’ fatigue-related decay to an extent. The blue hue of old hairsprings is due to this heat tempering process, which covers the steel coils with a fine oxide layer. This byproduct of tempering also happens to protect the hairsprings against corrosion. 

Temperature remained still the most immediate threat to the day-to-day accuracy of sprung timepieces. Fellow English clockmaker John Arnold (1736-1799) experimented with steel but also with precious metal hairsprings. He favoured gold springs, which were not very sensible to temperature changes. But being a soft metal, gold was more susceptible to fatigue related loss of stiffness and could not be tempered. Similar trials involved palladium-alloy springs.

Abraham-Louis Breguet (1747-1823), among others, experimented with cylindrical glass balance springs, which he believed to be better than their metallic counterparts. His trial results were mixed, although the glass springs fared better in terms of temperature stability. But the brittle nature of the material, along with its increased shift effect made them unsuitable replacements for metallic springs. Moreover, the glass tends to form uneven micro-crystals inside its lattice, thus making the spring less homogenous and stiffer. This behaviour is known as devitrification. 

Temperature compensation and the secondary error

Since it became clear to watchmakers that coming up with a hairspring that was not susceptible to temperature changes was improbable, they moved their focus to trying to counter the effects of the unstable hairspring.

Watchmakers started off with the simple observation that balance springs weakened at high temperatures and stiffened at lower temperatures. Holding this as a given fact, they begun researching into compensation methods that would cancel out the troubling effect. 

As we’ve explained in a past story about mechanical watch regulation, the natural frequency of a spring-balance system is dependent on the hairspring’s stiffness and the balance wheel’s moment of inertia. The shorted version is that for the same given spring, a balance with a higher moment of inertia beats slow, while another with a smaller moment beats conversely faster. 

Using this piece of information, watchmakers reasoned that a dynamic balance, whose moment of inertial would change in relation to temperature, could counteract the change in spring stiffness. 

This is how the bi-metallic compensation balances came to be. Pierre Le Roy (1717 -1785) invented the first bi-metallic compensation balances. Arnold, Thomas Earnshaw (1749-1829) and Ferdinand Berthoud (1727-1807) later made contributions to the concept.

The basic construction of a bi-metallic balance features cut compensation arms made of an inner layer of steel and a thicker, outer layer of brass. Screws or weights would be typically fitted to these arms, much like in modern balances. 

The device would slightly curve inwards or outwards at different  temperatures, because brass and steel have different linear temperature expansion coefficients (α) and their expansion was not even. 

At low temperatures, the brass strip contracts faster than the steel inner layer, causing the curves to move outward. This would in turn increases the moment of inertia of the balance and slow down the stiffened balance. At high temperatures the opposite was the case, with the brass expanding fast and turning the curves inward, decreasing the moment of inertia. This would speed up the weakened balance. The short animation below provides a dynamic explanation of how the device works. At first sight, the system seemed foolproof.

The oscillation of a bi-metallic balance wheel.

After thorough experimentation, especially with precise marine chronometers, watchmakers discovered an abnormality with the compensation mechanism. While the system worked well when set at the lower and higher bounds of the temperature spectrum (usually 0°C and 30°C respectively), the balance would not compensate well for the intermediate temperature values. 

The effect was dubbed the middle temperature error (MLE), also known as “secondary error”. The discovery of this phenomenon is commonly attributed to Ferdinand Berthoud in 1771. 

Having discovered the MLE, watchmakers were left wondering about what was the cause. One of the first explanations that held for a while was related to the mathematical expression of the balance frequency, where the polar moment variation would be linear while the spring stiffness change would be under a square root — so their ratio would not hold constant. 

The explanation was true in part, but insufficient. There was an underlying cause behind the MLE, but one which escaped watchmakers. That matter was finally solved and corrected in the latter half of the 19th century, by a Swiss physicist who then went on to win a Nobel prize.

The Guillaume balance

Charles Édouard Guillaume (1861-1938) was born to Swiss parents in Fleurier, Switzerland. His father was a watchmaker and the young Guillaume showed interest in marine chronometry. He took a different path from his father however, and pursued experimental physics, eventually earning a PhD in 1883 from ETH Zurich, one of Europe’s most prestigious technical universities.

He later headed the International Bureau of Weights and Measures, where he carried on with his personal research and experiments. After the metric system was adopted, the Bureau occupied themselves with building metre-long rulers made from a suitable material that would be as impervious to atmospheric changes as possible (heat and humidity).

A platinum-iridium alloy behaved the best, but the material was expensive. The bureau was in search of a cheaper alloy, but with similar qualities. This is when sample ingots of iron-nickel alloys came by Guillaume’s desk.  

Even before studying Invar alloys, Guillaume was preoccupied with the underlying reason behind the MLE defect. He eventually found the subtle effect that caused the abnormal behaviour. The steel-brass balance would vary its shape quasi-linearly in relation to temperature, while there was a curve in the spring’s stiffness change. The figure below explains it better. 

The dark yellow line shows how the brass expansion affects the running rate. The green line shows how the steel alone affects the running of the balance. Their joint action is shown by the straight line in grey. By coincidence, the quadratic coefficients (β) of brass and steel are sensibly the same, so they cancel out for the bi-metallic balance. This is why the dependence between temperature and rate change for such a balance is linear.

Figure adapted from Guillaume’s Nobel Prize lecture.

The blue downward slope shows the slowing effect of the hairspring as the temperature rises. Since the balance behaves linearly while the spring clearly does not, their respective effects can’t fully cancel out. The red line shows the compensated oscillator, an algebraic sum of the bi-metallic balance and spring effects. It is clear that such an oscillator’s rate remains dependent on the temperature. 

There are only two points O and O’ where the red slope intersects the horizontal axis — thus pointing to a zero rate change. Those points are usually the lower and upper bounds of temperature regulation, where the watch runs perfectly. The intermediate temperatures however lead to a slight but noticeable rate gain of 3-4 seconds per day.

Invar

As mentioned before, Guillaume came by steel-nickel alloys during his tenure at the International Bureau of Weights and Measures. He noticed an anomaly in the heat expansion behaviour of those alloys. For most two-metal alloys, the dilatation coefficient (α) sits somewhere between the respective expansion coefficients of the pure metal constituents. It was initially expected that a iron-nickel alloy would behave in a similar fashion.

What Guillaume observed was a seemingly erratic behaviour, with an expansion coefficient α that followed an odd curve which reached its minimum at a composition of 36% nickel. At that specific point, the linear expansion coefficient is 10 to 11 times smaller than that of steel. 

Diagram extracted from L. Defossez, Théorie générale de l’horlogerie Tome II,  showing the odd curves for the α and β coefficients in iron-nickel alloys; α’s variance with composition is shown by curve DEFG, while β’s is shown by curve IJKL

The quadratic coefficient β follows its own non-linear curve as well and has negative values for alloys with nickel concentrations of at least 36-37%. This subtracts from the already small linear expansion coefficient, making for a quasi-null temperature-related global change in dimensions. From this convenient invariability in size in relation to temperature change, Guillaume coined the term Invar for this interesting family of alloys.

Invar was famously used to replace the inner steel strip in bi-metallic balances. Since Invar expands different from steel, the compensation action of the cut balance wasn’t linear anymore, but followed its own curve. By 1899 Guillaume calculated the advantageous Invar alloy composition (about 44% nickel) which would cancel out the spring effect completely. Still part of the Invar family of alloys, this specific composition was referred to as Anibal.

Figure adapted from Guillaume’s Nobel Prize lecture.

The figure below shows how that works. The green line shows the Invar strip’s influence, which has a very different profile from that of steel. The grey line shows how the new brass-Invar balance affects the rate of the watch as temperature rises. Its curve is quasi-identical in profile to the spring’s (blue), but opposite in sign — so their sum is zero for all temperatures (flat red line for the oscillator). This became known as a Guillaume balance. 

Elinvar

A friend and collaborator of Guillaume’s, watchmaker Paul Perret (1854-1904) carried his own experiments with Invar alloys. The matter of compensation balances being settled, he sought to apply the wondrous alloy to the hairspring itself. When doing so, he noticed that the prototype springs would speed up as the temperature rose — a stark difference from all the other hairsprings in production. 

As shown in previous figures, as temperature increases, steel balance springs lead to a rate loss for the oscillator as they weaken. Perret was baffled to see the Invar springs do the exact opposite and transmitted his observations back to Guillaume. 

Perret’s experimentations led the physicist to conclude that iron-nickel alloys presented simultaneous expansion and thermoelastic anomalies. In 1912 Guillaume started adding chromium and manganese to the iron-nickel base, in order to concoct an alloy with a near-zero thermoelastic variance — an alloy that would keep its stiffness across a wide range of temperatures.  

According to Guillaume’s obituary in the Bulletin de la Société Neuchâteloise des Sciences Naturelles, the physicist’s work with Invar alloys concluded in 1919. Then Guillaume presented the Elinvar spring — a contraction of élasticité invariable, or “invariable elasticity” in English. Originally consisting of 34% nickel (much as early Invar samples), 54% iron and the addition of 12% chromium, Elinvar was a true breakthrough for watchmakers, since it rendered the need for complicated compensation balances obsolete. Elinvar was believed to keep the same Young’s modulus from -50°C to +100°C.

Figure extracted from L. Defossez, Théorie générale de l’horlogerie Tome II, showing the little variance of Elinvar’s Young’s modulus with temperature; on the segment C’D’ the change is almost null.

The introduction of Elinvar springs, which were malleable, corrosion resistant and even resistant to magnetic influence to a degree, changed the watchmaking industry. This ushered the new era of monometallic balances and mass-produced accurate timekeepers.

In 1920 Guillaume was awarded the Nobel Prize in Physics in recognition of his discovery of anomalies in iron-nickel alloys. His work proved very important to all sorts of engineering branches beyond horology. From structural engineering to diverse scientific instruments (seismographs of the time for example) and light bulbs, the discovery of Invar alloys proved to be one of the quieter but very important breakthroughs of the late 19th century. 

As a short aside of why Invar and its derivates seem impervious to temperature-induced changes, the answer is linked to its particular molecular behaviour. Iron-nickel alloys exhibit what is known as a magnetostriction effect — not present in neither pure iron nor pure nickel. A simple explanation is provided by M. F. Ashby et al. in the textbook Materials: Engineering science, processing and design.

Normal materials exhibit an increased atomic vibration when heat is added to them. This vibrations expands the lattice, effectively increasing the volume of said material. For iron-nickel alloys, the iron atoms in the lattice also have their own inherent magnetic moments. When the temperature rises, the magnetostriction causes the iron atoms to tighten together due to magnetic transition. 

In fact, the two events happen simultaneously and cancel each other (when the iron-nickel ratio is favourable) — thus leading to a quasi-null volume increase. The addition of “quasi-” was used throughout this story since a true canceling out of the opposing effects described rarely occurs, even though the residual errors are close to negligible.

Looking forward

The introduction of Elinvar was considered at the time the ultimate hairspring material and was widely adopted by watchmakers across the world. It was used it the last of marine chronometers and found its way to consumer pocket and eventually wrist-worn watches.

Elinvar was quickly adopted by both artisans and industrial manufacturers alike and remained the de facto hairspring material for a long while. George Daniels and Derek Pratt famously liked new old-stock Hamilton 22 caliber hairsprings made from Elinvar, which they hailed as the best ever produced. Currently active American watchmaker David Walter favours them as well, which speaks on how well Elinvar performs.

While Elinvar finally solved the issue of temperature-related rate change, a new disruptive factor became increasingly problematic: magnetism. As electrical networks and devices became more and more prevalent in our lives so did magnetic fields.

As mentioned, Elinvar has a limited non-magnetic quality, but it becomes magnetised by strong enough fields — which are now household occurrences: computers, speakers, various appliances. The wondrous hairspring slowly became insufficient, pushing a new generation of watchmakers and engineers to search for improved alloys.  

The world of Swiss watchmaking is a small one; everyone seems to know everyone. This is especially true among the exclusive ranks of enamellers. In total, there are about 120 practicing enamellers in Switzerland, largely concentrated in Geneva, which has been a leading hub for fine enamelling for more the 400 years.

Of these, four artisans have recently taken up residence at Émailleurs de la Cité (EC) in Geneva’s Old Town. A newly established enamel workshop founded by Rexhep Rexhepi of Akrivia and Florent Olivier Martin, EC crafts a small number of grand feu enamel dials annually for Mr Rexhepi’s own watches and for select clients like Biver.

Though recently opened, the workshop has the feel of a mature and highly organised operation, benefiting from the obvious experience of the staff – Mr Martin was formerly the production director at the respected dial specialist Olivier Vaucher – and the attention to detail for which Mr Rexhepi is known.

The enamel workshop is a fitting addition to his growing empire, and is conveniently located just steps away from Akrivia’s watchmaking atelier on Grand-Rue, the picturesque cobblestone thoroughfare that runs through the Old Town.

The hand-engraved gratté pattern is applied personally by Mr Rexhepi.

The art of enamel

Brands like Patek Philippe consider enamel a “rare handcraft”, and for good reason. While industrial groups like the Swatch Group seem to have largely mastered the production of quality enamel dials at (vast) scale, the very best dials still require the dexterity of an artist, the patience of a saint, the mind of a winemaker, and the tools of a dental clinic – more on this later.

Due to the complex, sensitive nature of the material, enamel dials are known to have a very high rejection rate; even with painstaking preparation and meticulous effort, many dials develop flaws during production that render them worthless. The cost of this wastage is rolled into the price of finished dials, which can push the value of a single dial into the low five-figure range.

It’s an almost organic process, and there are a lot of things that can go wrong. For example, if the enamel frit (essentially powdered glass and pigments) is not perfectly clean, the impurities can burn and stain the dial. Similarly, tiny air bubbles can act like ticking time bombs, popping when heated, creating pockmarks that can’t be polished out. Even fluctuations in the humidity and temperature in the workshop can change the behavior of the enamel.

But the finished dials that emerge successfully often possess a degree of ethereal perfection and permanence that makes the costly effort worthwhile.

A completed dial for the Rexhep Rexhepi Chronomètre Contemporain II Diamant

The initial stages: Grinding and preparation

The enameller starts by choosing a colour of enamel frit from a vast assortment kept in inventory. This sounds like it should be the easiest part of the process, but colour selection is actually quite nuanced since the colours often change when they are fired, with the final shade being determined by the specific firing temperature.

This requires the enameller to have a sommelier-like understanding of the behavior of different pigments at different temperatures, in order to be able to select the right coloured frit for the desired outcome.

Once the colour is chosen, the frit is ground manually with a mortar and pestle. Distilled water is used to wash the frit at different stages to remove any impurities that may be present. The grinding and washing process is repeated until the desired grain size is achieved; only the smallest, most even particles are used to ensure uniform behavior during heating and cooling.

Washing the enamel frit

The enamel is then carefully painted onto the surface of a grey gold dial base. Grey gold is an alloy of gold and palladium, prized by enamellers because remains stable even after repeated firings. To help the enamel adhere evenly, the dial blanks are left with an intentionally coarse unpolished surface.

Firing

Things start heating up when the dials are transferred to the firing station. The firing process begins by placing the dial in a dental-grade vacuum furnace, akin to a small oven that sucks out all the air while maintaining a precisely controllable temperature. This type of machine is more commonly used by dental technicians to create ceramic crowns, but it works just as well for enamel dials.

From left, the vacuum furnace, oven, and heating plate

By applying heat under vacuum, this device helps eliminate air bubbles prior to firing. In dental work, an air bubble can cause a crown to crack; in dial-making air bubbles can pop leaving behind unsightly divots in the dial surface.

The vacuum furnace in action

After a stint in the vacuum furnace, the dial takes a break on a dehumidifier plate. Once the desired resting temperature is reached, the dial goes into the oven, supported by a special holder designed to facilitate even heating.

The dehumidifier plate

An enamel dial going into the oven

Since enamel and grey gold have different coefficients of thermal expansion, the dials can warp when exposed to significant temperature fluctuations, causing the enamel to crack.

For this reason, all high-end dials, like those made at EC, are counter-enamelled, meaning the back of the dial is also enamelled. The counter-enamel functions like the stays on a suspension bridge, providing a counter-balancing force to keep the dial flat.

Hour markers for the Louis Vuitton x Rexhep Rexhepi LVRR-01 Chronographe à Sonnerie feature translucent enamel; here several are shown cooling

Polishing

After a dial has been fired and found to be within spec, the polishing stages begin. The dials are ground against progressively finer polishing wheels, following the same steps used to achieve the perfect optical-grade finish of eyeglass lenses. This methodical step-by-step polishing process eliminates the dimpled orange peel-like texture that is often seen on lesser enamel dials.

This is a very manual step that requires the artisan to be able to maintain even pressure and ‘feel’ when the dial is ready to proceed.

A look at what the dial looks like between polishing stages

The polishing stages are absolutely critical to achieving the flawless mirror-like perfection that makes the best enamel dials stand out.

A few days after visiting EC, I had the chance to discuss this exact topic over a quick breakfast with Jean-Claude Biver, who selected EC to make the dials for the Biver Automatique Japan Edition. Mr Biver lauded EC for making some of the best enamel dials he’s seen in his 50-odd years in watchmaking.

Tampography

Tampography is the process of printing the dial with a gelatinous transfer pad. A routine practice throughout the industry, we’ve seen this process before at other dial makers like F.P. Journe’s Les Cadraniers de Genève.

In short, the paint used on the dial is applied to a plate engraved with the master copy of the dial, which is then wiped clean with a blade, removing all the paint except what is left in the engraved markings. The egg-shaped transfer pad is then pressed down until it flattens out, picking up a painted image of the dial.

The ‘master copy’ of the dial

The plate then slides away, bringing the real dial into place underneath the transfer pad, which is then brought down swiftly, printing one layer on the dial. The process is usually repeated multiple times to achieve the glossy, domed markings that most collectors expect.

For the black enamel dial of the Chronomètre Contemporain II in platinum, a type of white acrylic paint is used. On the 18k rose gold model, which features a warm, translucent white enamel dial, enamel paint is used for the markings.

The enamel paint requires an extra layer of fondant, or clear enamel glaze, on top. This finishing touch has its roots in the grand tradition of the Geneva school of enamelling, which first championed the use of clear fondant as a means of protection for elaborate miniature enamel paintings.

While the tampography workshop was being renovated, construction workers discovered something strange. Carved into the foundation, which dates back centuries, a carved face was discovered, which seems to be a charming caricature with long lashes and a bowl cut.

The EC team is still deciding what to name this character, but they’ve already finalised plans to make this the ‘face’ of the workshop in the form of their maker’s mark. In the future, all EC dials will bear this emblem as a hallmark hammered into the back of the grey gold dial base.

The EC maker’s mark

Closing thoughts

Over the years, I’ve seen enough enamel dials with dimpled, uneven surfaces to feel slightly jaded about the whole proposition of enamel. But seeing the process at EC end-to-end opened my eyes to just how much control skilled artisans can exert over this unpredictable medium. Yes, the rejection rate is high, but the perfection of the dials that do make it through feels hard-won.

The enamel’s sensitivity to things like temperature and humidity reminds me of winemaking. Like grapes in a vineyard, enamel is capricious and demanding. Like a vintner, the enameller must anticipate the effect that small actions will have on later stages of the process, and the smallest oversight at any point can ruin an otherwise perfect creation.

Reflecting on the process end-to-end, enamelwork is a fascinating blend of art and science. Though the process for creating modern enamel dials benefits from tools like computer-controlled vacuum furnaces, there is a great deal of artistry found in the enameller’s dexterous touch and intuition for transformation.

]]> https://watchesbysjx.com/2025/07/elliot-cabot-lee-watch-collector.html Tue, 01 Jul 2025 00:00:23 +0000 https://watchesbysjx.com/?p=261146 Between 1885 and 1920, Elliot Cabot Lee (1854-1920) quietly built one of the world’s largest collections of very complicated watches, but unlike the famous rivals Henry Graves Jr. or James Ward Packard, both of whom favoured Swiss watches (and primarily Patek Philippe), Lee was a devotee of English watchmaking during its heyday. Many remarkable watches […]]]>

Between 1885 and 1920, Elliot Cabot Lee (1854-1920) quietly built one of the world’s largest collections of very complicated watches, but unlike the famous rivals Henry Graves Jr. or James Ward Packard, both of whom favoured Swiss watches (and primarily Patek Philippe), Lee was a devotee of English watchmaking during its heyday.

Many remarkable watches that were commissioned by Lee, or passed through his collection, have surfaced over the last few years, such as the J.W. Benson Supercomplication, the Dent Astronomical watch, or even J.P. Morgan’s pocket-planetarium, but with their provenance unknown.

Most of Lee’s collection of pocket watches. Image – The National Jeweler 1922

A patrician collector

Elliot Cabot Lee was born on April 16th, 1854 in Brookline, Massachusetts. Both of Lee’s parents hailed from Boston Brahmin families and were third cousins. His father, Henry Lee Jr., was a partner at investment bank Lee, Higginson & Company, where Lee also worked, though only briefly. His mother, Elizabeth Perkins Cabot, was the granddaughter of the extremely wealthy Thomas Handasyd Perkins – a slaver turned philanthropist.

Lee graduated from Harvard with a law degree and passed the bar, though he seems to have practiced law little if at all. He was well-travelled and well-read, accumulating a notable book collection, according to the Brookline Historical society.

Besides his watch collection, Lee also took an interest in the nascent automobile. He built a garage, or an “automobile stable” as it was called at the time, on the Perkins Estate inherited from his mother’s family, and was involved in the Phelps and Shawmut motor companies according to volume 18 of The Automobile. In 1905, Lee’s peers elected him president of the American Automobile Association (AAA) as reported by American Motorist.

Elliot C. Lee. Images – American Motorist 1912, The Automobile January 1904

Most of what we know of the collection comes from John J. Kingsley of Boston, a watch retailer, watchmaker and friend, to whom Lee entrusted his collection. Both men were AAA members, and Kingsley aided Lee in planning his commissions. Kingsley kept the collection on display in his Boylston Street store for a time in 1924 according to an advertisement in The Boston Traveler newspaper and brought a selection of Lee’s watches from Massachusetts to James Ward Packard’s home in Ohio for his private viewing, as mentioned by Stacy Perman in A Grand Complication, a book about the ostensible rivalry between Graves and Packard.

Lee’s collection included clocks as well, one of which, a baroque German astronomical clock, is on display at the Museum of Fine Arts in Boston. Kingsley said that Lee was in the habit of gifting watches from his collection to others.

What sort of watches did Lee prune from the collection? The only one I managed to track down was a pocket chronometer with tourbillon, spring detent escapement and fusee signed by Victor Kullberg sold by Christie’s in 1999. The late Reinhard Meis depicts this watch on page 229 of Das Tourbillon.

Advertisement for the exhibition of Lee’s collection. Images – The Boston Traveler. March 13, 1924 J.J. Kingsley with the collection, The Springfield Daily Republican March 6, 1924

Lee was known to carry multiple watches at once and was rarely seen twice with the same, according to Kingsley. An anecdote in volume seven of The Automobile Magazine affirms this: “It used to be a regular performance in the old days to casually ask Mr Lee if he had the time. This was usually followed by his consulting a watch the like of which you were sure never to have seen before. Questioning the accuracy of the timepiece, while it brought a pained expression to Mr Lee’s face, was quickly followed by his bringing forth another equally unique time-teller as proof that the first one told only the truth. I never saw the occasion when Mr. Lee couldn’t produce these proofs in quantity sufficient to convince any doubter, and I never saw him produce the same watches when on some other day the same performance was gone through with.”

His obsession with accuracy led to the installation of a regulator clock in his home, mounted on brickwork – probably best as old New England houses tend to sway due to construction and weather.

The Perkins Estate. Image – Massachusetts Historical Commission 1983

Lee never married and didn’t stay in the same place long enough to. He spent at least five (non-continuous) years in Europe and one in Asia; within the United States he moved from Massachusetts to Florida, to California, to Massachusetts again and finally to North Carolina, where he died in February 1920.

While in Massachusetts, he lived with his sister Elizabeth and her family in an apartment on the Perkins estate. The Gentleman Mr Shattuck, a biography of Lee’s nephew, mentions that Lee “carried innumerable watches on his person, and [the] children loved to come up to him and ask: ‘what time is it [in Paris] Mr Lee?’ and he would whip out a watch and say: ‘six o’clock.”

Lee never children of his own but remained in close personal relationships with his nieces and nephews in their adult lives.

The commissioner-collector

Nearly all of Lee’s watches were from the major English firms, such as Dent, Smith, Benson, and Player, though with the notable absence of Frodsham. The English approach to watchmaking deviated from the Swiss style that is dominant today.

English watchmakers did not waste time on bevelling, striping, or perlage and instead let acid do most of the work for them. Monolithic, gilt, three-quarter plates were the most characteristic feature of English watchmaking. Jewels were often set into flush gold or brass bushes, rather than being rubbed into the bridges directly. Incidentally, English labour was much more expensive than Swiss.

Watch 1: S. Smith & Son 304-1. Image – Antiquorum

Good English watches typically used free-sprung balances (vanishingly rare in Swiss pocket watches) and diamond end stones for the balance (a practice the Swiss reserved for only simple, very high-grade watches). The English had their own detached lever escapement, now known as the English lever, which used a pointed (usually brass) escape wheel instead of the club-foot profile used in the Swiss lever.

They also disagreed with the Swiss on what constitutes a chronometer. The Swiss would tell say it’s based on performance – any watch can be a chronometer if it passes an independent test of its precision. The English would have said that a chronometer must use a chronometer (detent) escapement, which was usually paired with a helical balance spring and free-sprung compensation balance. Many of Lee’s watches were chronometers by both English and Swiss reckoning.

Watch 3: Dent 33’139. Image – Sotheby’s

English watches trended larger than their continental counterparts and more often included chronometry-focused features such as the spring detent escapement, revolving escapements (tourbillons and karrusels), chain and fusee and up/down indicator. The English were eager to combine these features with complications, which the Swiss were loath to do.

That said, by the turn of the century, complicated English watches were as much Swiss as they were English. Essentially, all chiming complications originated from the Vallee de Joux, with many passing through Capt & Cie.’s workshop in Le Solliat – which was located on the same street as Philippe Dufour’s is today. Even English perpetual calendar and some chronograph works of this period were Swiss – a fact the English houses were cagey about.

The Lee collection contained five extremely complicated double-faced watches: two signed Dent (22, and not shown), one J.W. Benson (10), one J. Player & Son (11), and possibly one S. Smith & Son (not shown). Other complicated watches included an oversized S. Smith & Son clock watch with retrograde perpetual calendar (1), a grand complicated Dent with tourbillon (21) and two other Dent perpetual clock watches (2, likely watch no. 33’581, and 4).

Most of Lee’s collection of pocket watches. Image – The National Jeweler 1922

Lee preferred open-face watches, the only complicated hunter-cased watch being an S. Smith & Son chronograph with hour and minute totalisers and a twelve-minute flying tourbillon (9). It’s notable for being one of the first flying tourbillions and two-button chronographs. The sprung front cover on this watch has been cut and fitted with a crystal, effectively turning it into an open-face watch.

Another chronograph (12) has registers dropped below the centre line, as seen on a few other English watches, including Packard’s. All simple watches with up/down (5, 14, 17, and 20) can be assumed to be tourbillons, karrusels, fusees, or something similar until proven otherwise.

Only two watches (15 and 16) have typical Swiss-styled cases. Watches 6 and 13 can be attributed to Jules Jürgensen based on the distinctive bow. All watches shown are modern, or were at the time; the sole exception being a Breguet Souscription (7), which was already an antique a hundred years ago.

Watch 9: S. Smith & Son 1901-23. Image – Antiquorum

The Dent Astronomical Watch

Dent was amongst the most prestigious English names and widely imitated. Chronometer maker Edward John Dent (1790–1853) went into business with John Arnold’s son, who apprenticed under Abraham-Louis Breguet, in 1830 before striking out on his own ten years later. His firm made the Great Clock of Westminster, colloquially called Big Ben, though he died before completion. Dent’s company also retailed watches, both English and the best Swiss imports.

Dent no. 32’573 (finished around 1904) is the best-documented watch in Lee’s collection, thanks to Daniel Aubert’s research published in the 1988 edition of Chronométrophilia. Dent ordered the movement from Nicole Nielsen, Capt & Cie.’s partner in England and the leading supplier of complicated movements during Lee’s day.

Founded in 1839 as Nicole & Capt, the company later became Nicole, Nielsen & Co. when Danish watchmaker Sophus Emil Nielsen joined as partner around 1870. Besides founding the company, Adolphe Nicole, or one of his employees, invented the modern chronograph, and the rattrapante. George Daniels lauded Nicole Nielsen’s tourbillons in particular as the best a watch can be, and it’s hard to disagree.

Watch 22: Dent no. 32’573. Image – Sotheby’s

The austere enamel front dial belies the engine-turned silver astronomical dial on the back. The 27’’’ movement itself is oversized but otherwise a typical minute repeating clock watch with grande et petite sonnerie on two gongs made from a Swiss ebauche.

Dent sold another double dialled watch, no. 32’545, with the same base movement but with a perpetual calendar with date from the centre on the back. An external regulator is under the bezel of both watches, allowing easy adjustment without removing the rear dial. Other double-dialled watches, such as the Leroy 01, Graves Supercomplication and Star Caliber 2000 make use of similar systems.

Watch 22: Dent no. 32’573, under the front and rear dials. Image – Sotheby’s

The astronomical complications are the work of Leon Aubert, who likely contributed to other watches in the collection as well.

The mechanisms for the times of sunrise and sunset, equation of time, morning and evening stars, and signs of the zodiac connect to the perpetual calendar on the front through the hollow going barrel arbour. Cams program the equation of time, time of sunrise and time of sunset; each cam sits on a wheel that turns once per year, driving their respective hands. The longer, globe-tipped hand completes one revolution each year, acting as an annual calendar and indicating the zodiacs.

Watch 22: Dent no. 32’573, disks and calender plate removed. Image – Sotheby’s

The most unusual of the many esoteric mechanisms are the morning/evening stars, and times of moonrise/moonset. Apertures labelled morning and evening stars show the planets (Mars, Mercury, Venus, Jupiter, or Saturn) that are visible in the sky each morning and evening on polished gold disks. These, along with the phases and age of the moon, are driven separately from the rest of the astronomical indications. A retrograde system with two saw-tooth cams uses one cam for moonrise and the other for moonset.

J.P. Morgan’s Watch

John Piermont Morgan commissioned watch 11, and Lee acquired it after Morgan’s death in 1913. It certainly looks like the type of watch a man so rich he bailed out the US government (twice) would own. J. Player & Son was a Coventry-based watchmaker, a city that was once the heart of the English watch and clock industry. While not as well known as the London-based firms, Player made some exceptional watches, including Morgan’s.

Watch 11: J. Player Astronomical watch. Image – HIA Journal, 1947

The watch is a striking anachronism; at first glance, I would have guessed it to be nearly a hundred years older than its true age. In context, this makes perfect sense as J.P. Morgan mostly collected antique watches and likely owned some of George Margetts’s astronomical watches from the late 1700s, which must have inspired the Player.

George Margetts 312. Image – Sotheby’s

The miniature dial in the centre gives mean solar (conventional) time and supports the mobile elliptical frame that represents the visible sky north of 23 ½ degrees latitude. The silver moon rotates once every 24 hours, 50 minutes and 28 seconds, showing the passage of the moon across the sky and the tides. Below this is a sun hand which turns once every 24 hours; these two disks interact to show the age and phase of the moon.

Finally, the planisphere disk rotates once about every 23 hours, 56 minutes and four seconds – which is one sidereal day. The interaction of this disk with the sun hand shows the solar declination, months of year and zodiacs. The Margetts watch functions similarly.

Both side of the movement in Morgan’s watch. Image – Colin Crisford

On the back is an engine-turned dial with a perpetual calendar that indicates the date by hand from the centre, this style of calendar is used in several English watches, including the one made by Dent for James Ward Packard and the S. Smith & Son 309-2 (made from a Louis-Elisee Piguet ebauche).

Besides the date, the calendar tracks weekdays, times of sunrise and sunset, and equation of time. Underneath everything is an oversized grande et petite sonnerie clock watch movement very similar to the one used in the previous Dent. Most notable is the massive tourbillon visible through the dial, the balance alone is larger than some entire movements. While tourbillons are common today, they were rarer and more revered in Lee’s time with only a few highly skilled watchmakers specialising in their construction and adjustment.

The J.W. Benson “supercomplication”

Another of Lee’s watches was a double-dialled “supercomplication” by J.W. Benson. Interestingly, the Benson and Morgan’s J. Player both ended up in the collection of Benjamin Mellenhoff, once the head watchmaker at Tiffany & Co. in New York, but the two watches parted ways after his death.

J.W. Benson was a London-based retailer of jewellery, diamonds, silverware, and other luxury goods. The firm also sold watches and clocks under their own brands, including a relatively large number of complicated watches – even triple and grand complications. Benson claimed to make movements at its Ludgate Hill factory, which may have been true for simple watches, though certainly outsourced complications.

Watch 10: J.W. Benson triple chronograph. Image – Christie’s

On the front is an uncommon triple chronograph, which is likely three chronographs stacked on top of each other, or two stacked chronographs and one rattrapante.

When the crown is pressed all three chronographs engage, when pressed a second time one is stopped, then the second and finally the third. A fifth and final press resets all three chronographs at once. Only the last chronograph has a minute counter. The tachymeter is calibrated for a fourth of a mile. Note this is a dédoublante, not a rattrapante, since the stopped hands cannot be made to catch up to the one still advancing.

Example of a Swiss triple chronograph. Image – Bonhams

Under the bezel is a concealed date, for what is most likely a perpetual calendar,  and strike mode selectors for grande sonnerie, petite sonnerie and silence. The watch imitates Westminster chimes and can do so to the minute on demand by using the trip near 4:00. The back is likely also the work of Leon Aubert, with a planisphere showing the sky north of 23 ½ degrees latitude, time of sunrise and sunset, passage of the zodiacs and equation of time. Arrayed across the dial are time offsets of most major cities from Greenwich mean time for easy reference, though I’m sure Lee knew the time off-sets for all these cities by heart.

Unbelievably, watch 18 is also a triple chronograph by J.W. Benson, but lacks a minute counter. This watch uses two stacked chronographs and one rattrapante on the back of the same oversized clock watch movement used in the Dent Astronomical watch. The case is also unusual, with an oblong bow, and engraved case band.

Watch 18. Image – Colin Crisford

Lee’s “supercomplication”, Dent 36’544

The most elusive of Lee’s known super-complications is the second Dent. The only pictures I can provide are from articles in The National Jeweler and The Jeweler’s Circular.

According to F. Louis Elisée Piguet: Six Générations d’Horlogers de La Vallée de Joux, Louis Elysee Piguet’s archives list a pair of matching duo-face English-style ebauches (8’400 and 8’401). Piguet sold both movements to Capt & Cie. in 1904 for the princely sum of 3500 francs each, so there are likely two of these watches. David Penny’s reprint of the 1910 Nicole, Nielsen & Co. catalog lists these movements as the Type 50, the most complicated watch offered, with pricing on request.

Signed Dent, not shown in the collection spread. The pins on either side of the crown set the time and alarm, while the buttons likely actuate the rattrapante and winding rocker. Image – The Jewelers Circular and Horological Review 1924

Three barrels power the movement and striking mechanism, all wound from the crown with the aid of a rocker mechanism also seen on other three-train movements by Louis Elysee Piguet. On the front is a split-second chronograph with stacked minutes and hours registers at three o’clock, while this may not seem significant now, chronographs with hours totalisers were extremely rare at the time.

The alarm, which is wound externally, can set the alarm to the exact minute from the dial at nine o’clock. There is a power reserve and barometer at 12 o’clock. On the back is another perpetual calendar with date from the centre, along with day, month, leap year cycle and moon phase. The watch covertly has the equation of time, likely hidden under the rear bezel, like the J.W. Benson’s concealed date, and a one-minute tourbillon hiding between the dials.

An example of a watch with seven gongs and two discrete striking systems, one of which uses a pinned cylinder in place of racks to play a melody on the new hour. Such watches were usually made for the English market. Image – Antiquorum

In a typical repeater or clock watch with a single quarters rack, the first quarter is indicated by a pair of high and low notes, the second by two pairs of the same notes, the third by three and the fourth by none. A quarters rack typically chimes notes 1, 2, 3 then the first, second, and third quarters will always follow the same pattern of notes 1, 2-1, and 3-2-1. Since the melody of Westminster chimes would be 1-2, 3-4, 5, 1-2, 3, 4 ,5, four different racks are needed to reproduce the quarters accurately.

Patek Philippe’s “Duc de Regla” of 1910 and Star Calibre 2000 also have four-rack Westminster systems, while the Graves Supercomplication (and most other watches claiming Westminster chimes) are imitations using a single quarters-rack. Lee’s watch cost around US$18,000 according to Kingsley. For reference, the Graves Supercomplication that was ordered decades later was only around US$15,000, reflecting the relative cost disparity between English and Swiss watchmaking at the time.

In addition to the Westminster chimes, Lee’s super-complication also has an independent minute repeater, or even a minute repeating grade et petite sonnerie on two gongs, which is why you can see a total of five quarters racks, two hours racks, and one minutes rack in the picture. Assuming five gongs in the Westminster (four for quarters and one for hours), two for the normal strikes and one for the alarm, the watch has eight gongs. Kingsley said the watch comprised 3,000 parts, which I suspect was an exaggeration, but not by much.

Dent super-complication parts spread. Image – Boston Evening Transcript. March 15, 1924

Mystery S. Smith & Son

Also described by Kingsley, but not pictured, is a 75 mm diameter, 38 mm-thick tourbillon by S. Smith & Son, with chimes on four gongs, a “double chronograph” with hours and minutes totalisers, perpetual calendar, signs of the zodiac, equation of time, moon phase, and power reserve indicator. Kingsley didn’t mention if the watch was double-dialled, but noted a silver dial with a gold inlay.

Founded by Samual Smith, S. Smith & Son was a retailer similar to J.W. Benson in Lee’s day, but leaned into manufacturing after the war. Smiths became a major manufacturer of instrumentation, clocks, and wristwatches. Later known as Smiths, the firm wound down its watchmaking division by the 1980s, but the conglomerate is still active in a range of industrial engineering sectors, including gaskets, tubing, security products, and electronics.

S. Smith & Son “Astronomical Watch”. Image – The Graphic November 19, 1921, page 598

S. Smith & Son’s “Astronomical Watch”, commissioned by an unknown American client before the First World War according to The Graphic, is approximately the same diameter and thickness. The watch has a perpetual calender, equation of time, up/down, chronograph with hours and minutes totalisers, tourbillon regulator, and grande et petite sonnerie with trip minute repeating.

The gold inlaid silver dial on the back has hours and minutes of sidereal time, geared to a planisphere which displays the sky above London – 315 hand-painted stars include all constellations of the zodiac. The “Astronomical Watch”, is not a perfect fit, as it lacks split-seconds and Westminster chimes, however it would be an extraordinary coincidence if the two were unrelated.

S. Smith & Son “Astronomical Watch”. Image – The Graphic November 19, 1921, Page 598

Interestingly, this watch passed through the hands of Audemars Piguet, where it was nicknamed “Grosse Piece”, reflecting both its size and complication. Today it remains the most complicated movement Audemars Piguet has been involved in producing. The war delayed completion of the watch until 1921, after Lee’s death. If these two watches are the same, it would explain why it’s estranged from the rest of Lee’s collection.

Lee’s Legacy

Why do we remember Graves and Packard but not Lee? Probably because Lee almost exclusively patronised long-gone English watchmakers. Without Patek Philippe fanning the flames of dubious Graves-Packard rivalry, would we remember the pair today?

Elliot C. Lee isn’t forgotten though, he’s best known today as president of the AAA and an, albeit unsuccessful, automotive entrepreneur – remembered for what he did, not what he bought.

We thank David Penney for vetting the characterisation of English watchmaking, his insights into watches 3 and 9, and reprinting the 1910 Nicole Nielsen & Co. catalog.

Abraham-Louis Breguet (1747-1823) stands among the most revered names in horology, celebrated for innovations that shaped modern watchmaking. While his tourbillon, self-winding mechanism, and anti-shock system are widely acknowledged, his work in astronomical timekeeping, particularly equation of time (EOT) watches, remain one of Breguet’s most intricate yet less-explored achievements.

With 2025 marking the 250th anniversary of his birth, this guide offers the most comprehensive study of every known EOT timepiece made during his lifetime, including pocket watch no. 160 “Marie Antoinette”, expanding on our prior analysis of the complication (in parts I and II).

No. 160 as pictured at the recent exhibition in London’s Science Museum. Image – Baruch Coutts

Looking at the stars

Breguet operated in an era where precision timekeeping was dictated by astronomy, and his workshop, positioned at the heart of Paris’s scientific and commercial networks, was uniquely placed to serve scientists, navigators, and royalty who required accurate solar and mean time readings.

Rather than settling on a single method for displaying and correcting the EOT, he explored multiple mechanical solutions, refining some while revisiting earlier ideas when necessary. His approach does not follow a strictly linear evolution but instead reflects a dynamic cycle of innovation, mechanical experimentation, and adaptation.

Breguet’s cam-driven system with feeler to indicate EOT, as found in pocket watch no. 3862

As Breguet passed away in 1823, some of the timepieces included here were completed under the direction of his son, Antoine-Louis Breguet (1776-1858), who continued the firm’s work while maintaining his father’s standards. However, the lack of access to Breguet’s complete archives remains a handicap in reconstructing the full scope of his work. If anyone is aware of an EOT watch not included in this research, please let us know, we welcome any additional information that can help refine this study.

A Spectrum of Solutions: EOT Displays & Mechanical Evolution

Breguet’s approach to EOT was not a single trajectory of refinement but rather a continuous process of experimentation, revision, and the occasional return to earlier concepts. Over more than five decades, he produced 21 functional EOT pocket watches, moving between different designs rather than following a strictly linear progression. His willingness to reintroduce earlier ideas in later models suggests that he did not see one solution as inherently superior to another but instead tailored each execution to suit its movement architecture and intended owner.

The choice of approach was dictated by the function and audience of each watch. Scientists required precise solar readings, navigators relied on astronomical calculations, and aristocratic patrons sought technical ingenuity paired with aesthetic refinement. As a result, Breguet’s EOT mechanisms ranged from subsidiary displays (e.g., No. 92 and 160) to “running” EOT, also known as équation marchante, (e.g., No. 1348 and 2614) and, ultimately, to dual-dial layouts (e.g., No. 1226 and 3863).

The movement of watch no. 217. Image – Christie’s

The introduction of these indications, made possible by differential gearing, allowed both time scales to be displayed simultaneously on a single or dual dial, eliminating the need for manual calculations. Yet even after refining this system, Breguet continued producing cam and lever-driven EOT watches, reinforcing that his work was not about replacing one approach with another but selecting the most suitable solution for each watch’s technical demands.

Though Breguet spearheaded these advancements, he was not working in isolation. His son, Antoine-Louis, played a crucial role in refining precision during the 1820s, particularly in the adaptation of EOT mechanisms to what was then considered ultra-thin designs.

Meanwhile, his pupil Jean-Charles Oudin (1768-1840), better known as Charles Oudin, later expanded upon these principles in his own timepieces produced in the Palais-Royal workshop established after he left Breguet, demonstrating the master’s techniques influenced a broader network of watchmakers. Their combined efforts ensured that Breguet’s EOT watches were not only technically sophisticated but also highly adaptable, proving that his legacy was as much about versatility as it was about mechanical precision.

A Unique Experiment & Charles Oudin

The earliest known attempt by Breguet to display the EOT in a portable watch predates his mature system by several years. Long before the introduction of more conventional indications, he experimented with more direct solutions. The only example of its kind known to have been produced by Breguet, No. 444 stands as a unique experiment, offering rare insight into his earliest efforts to translate astronomical time into mechanical form.

Breguet No. 444 (c. 1779)

Breguet No. 444, completed in 1779 but sold only two decades later on April 7, 1799, to a Mr Renble, represents an early attempt at integrating the EOT into a pocket watch. Unlike later models with cam-driven subsidiary displays, No. 444 employed a rather unusual and exotic pivoted auxiliary hand mounted directly on the meantime hand. Though eventually replaced by more advanced systems, it remains a significant step in Breguet’s use of EOT indications.

Breguet No, 444 (ca. 1779). Image – The Art of Breguet by George Daniels

Oudin, one of Breguet’s most skilled apprentices, was actively engaged in horological advancements at the time of No. 444’s production. Later appointed Watchmaker to Napoleon I, Oudin’s early training under Breguet shaped his expertise in astronomical horology.

The dual signature on No. 444, of both Breguet and Oudin, suggests Oudin played a direct role in the development of its EOT system. Whether it was a collaboration or a delegated project, the watch aligns closely with Oudin’s later precision work. A second known example, signed solely by Oudin, is housed in the Musée Paul Dupuy in Toulouse, reinforcing his contribution. Another related watch, No. 4970, carries the inscription “Équation inventée par Charles Oudin Palais-Royal n° 52”, indicating that he continued refining this display method beyond his tenure in Breguet’s workshop.

The equation cam at the centre of No. 444 (ca. 1779). Image – The Art of Breguet by George Daniels

A fundamental limitation of No. 444 was that its EOT indication remained relevant only once per day. The watch’s calendar disc and equation cam completed a full 360º revolution annually, yet the EOT hand, pivoted on the hour hand, only reflected the equation deviation at noon. For the rest of the day, its position became meaningless, failing to provide a continuous reference for the equation of time.

Unlike later designs where a kidney-shaped cam allowed for dynamic, real-time EOT adjustments, No. 444’s system required the wearer to infer the correction manually, relying on a static offset that did not update throughout the day. While mechanically intriguing, this approach proved less practical than the continuously variable indications that followed, which ensured greater precision and legibility.

No 444 (ca. 1779) @ The Art of Breguet by George Daniels (this view illustrates the feeler system that connects the equation cam to the superimposed equation hand. As the cam rotates, the feeler follows its contour, transmitting the variations in the Equation of Time to the equation hand, which displays the correction on a time scale divided into 5-minute intervals)

Mechanically, No. 444 follows Breguet’s Souscription model, balancing precision with streamlined production. It features a manually wound central barrel, a three-armed plain balance, and a ruby cylinder escapement, a system Breguet favoured before transitioning to lever and tourbillon escapements. A spiral steel balance spring with a compensation curb ensured temperature stability. The engine-turned silver dial incorporates a rotating centre disc for the date, an unusual feature for early Souscription watches.

The movement of No. 444 (ca. 1779). Image – The Art of Breguet by George Daniels

Housed in a 62 mm gold guilloché case, No. 444’s cuvette bears the inscription “Inventée par Charles Oudin” alongside Breguet’s signature, further confirming Oudin’s involvement. Once part of the David Salomons collection, No. 444 stands among the earliest recorded portable timepieces featuring an EOT display, marking an essential step in the transition from astronomical tables to mechanical solar time indications.

Although later refinements improved readability and efficiency, No. 444 remains a key example of Breguet’s early attempts to reconcile solar variations in timekeeping. It also underscores Oudin’s influence, as his later work carried forward Breguet’s teachings.

From Experiment to Masterpiece – 1783 to 1790s

While No. 444 marked Breguet’s first recorded attempt at integrating an EOT indication, it remained an isolated experiment. It was only in the years that followed, beginning around 1783, that Breguet began developing a coherent mechanical approach to the complication, one that would reach full maturity in a series of extraordinary timepieces.

Breguet No. 92 (c. 1783-1785)

Four years after the inaugural No. 444, Breguet began work on two exceptional timepieces, No. 92 and No. 160, marking his first fully developed executions of the EOT complication.

No. 92, commissioned in 1783 by the Duc de Praslin, a patron of horology and member of the distinguished Choiseul-Praslin family, features a double-sided construction.

As a double-sided display watch, the recto side presents the primary timekeeping functions alongside a perpetual calendar with three retrograde indicators and an EOT indication on a subsidiary display.

Breguet No. 92, front and back. Image – Musée des Arts et Métiers, Paris

The verso side features a chased gold dial, incorporating a moon phase, a power reserve indicator, and regulators for both sonnerie speed and timekeeping adjustment. The movement is powered by a lever escapement, a compensated balance wheel, and a balance spring with a terminal curve, ensuring both precision and stability.

Breguet No. 160 (c. 1783)

Unlike No. 92’s double-sided design, No. 160 features a rock crystal dial, exposing its intricate mechanics. An enamel dial was also provided. Announced as the most advanced timepiece of its era, with no restrictions on cost or time, it incorporated every known complication.

The transparent dial integrates EOT, perpetual calendar, thermometer, and state-of-winding indicator. The EOT mechanisms in both watches introduced the subsidiary display indication driven by the cam and lever system that calculated the difference between mean and solar time.

Breguet No. 160. Image – L.A. Mayer Museum for Islamic Art, Jerusalem

While No. 92 employs separate retrograde indications for the day, date, and months, making it functionally rich despite its double-sided configuration, No. 160 refines these concepts further in a single-dial format. Beyond the EOT, No. 92 includes a ten-minute repeater on a bell and a minute repeater on a gong, while No. 160 incorporates a more complex chain-driven system. Another shared attribute is the independent seconds, a rare feature at the time, highlighting Breguet’s focus on precision and scientific horology.

Breguet No. 160. Image – L.A. Mayer Museum for Islamic Art, Jerusalem

The French Revolution of 1789 disrupted the completion of both watches. No. 92 was eventually finished and sold in 1805 for 4,800 francs to the Duc de Praslin, a devoted patron of Breguet. No. 160, however, remained unfinished until 1827, long after Breguet’s death, when his successors completed the watch.

Sir David Salomons, a British horological scholar and collector, played a key role in preserving Breguet’s legacy, publishing influential works on the brand. He later acquired both No. 92 and No. 160, ensuring their survival and historical documentation.

Breguet No. 160 in profile. Image – L.A. Mayer Museum for Islamic Art, Jerusalem

No. 92 ultimately entered the collection of the Musée des Arts et Métiers in Paris, while No. 160 followed a different path. On May 3, 1917, Salomons first noticed No. 160 displayed in the window of Louis Albert Desoutter’s shop near Regent Street. Fascinated by its complexity, he researched its provenance before acquiring it. Upon his passing, it was inherited by his wife. It later became part of the collection of his great-niece, Vera Salomons, who housed it at the L.A. Mayer Institute for Islamic Art in Jerusalem.

The reverse of No. 160. Image – L.A. Mayer Museum for Islamic Art, Jerusalem

Curiously, both watches fell victim to theft. No. 92 was stolen from the Musée des Arts et Métiers in Paris but was later recovered when the thief attempted to have it repaired. No. 160 was taken in the notorious 1983 burglary in Jerusalem, along with the storied Breguet “Marie Antoinette”, vanishing for over two decades before being recovered in 2007.

Breguet No. 217 (c. 1790s)

Building upon this groundwork, Breguet continued refining his approach to the EOT complication, integrating it into sophisticated mechanisms. Nearly a decade after work began on No. 92 and No. 160, he adapted these principles to a self-winding design, resulting in No. 217, known as the “Havas perpetuelle” after one of its former owners, the founder of the eponymous news agency.

Breguet No 217 (ca. 1790s). Image – Christie’s

One of only two known perpetuelle watches with an EOT function, alongside the legendary No. 160 Marie Antoinette, this timepiece merges self-winding technology, an EOT display, and a perpetual calendar into a single, highly refined mechanism, securing its place as a landmark in horology.

Sold in 1800 to General Jean Victor Marie Moreau for 3,600 francs, it was later returned to Breguet after Moreau’s death in 1813. General Moreau (1763–1813) played a key role in Napoleon’s rise to power but later fell out of favour, leading to his exile to the United States in 1804. He returned to Europe in 1813, joining the Russian army against Napoleon, only to be mortally wounded at the Battle of Dresden.

Refurbished and resold on December 31, 1817, to Charles-Louis Havas (1783–1858) for 4,800 francs, the watch resurfaced over a century later, achieving US$3.3 million at Christie’s Geneva in 2016. Havas, the second owner, was a banker and publisher who founded Agence Havas in 1835, the world’s first news agency and the precursor to Reuters and Agence France-Presse, better known today as AFP.

Breguet No 217 (ca. 1790s). Image – Christie’s

No. 217 is a self-winding Perpetuelle featuring a quarter repeater à toc, which taps the case to indicate the nearest quarter-hour. Its EOT display graduated from +15 to -15 minutes, operates via a cam-driven system linked to the month calendar wheel for continuous solar time correction. The perpetual calendar integrates a subsidiary seconds dial with the month indication alongside a date aperture signalled by a gold arrow pointer. A 60-hour power reserve indicator ensures reliable operation.

Breguet No 217 movement with EOT cam visible (ca. 1790s). Image – Christie’s

The engine-turned silver dial features Roman numerals, outer dot minute divisions, and gold Breguet hands, with subsidiary displays for the power reserve and EOT indications. The movement incorporates a jewelled lever escapement, a four-arm compensated balance wheel with platinum adjusting weights, and a blued steel helical balance spring.

A platinum oscillating weight drives the winding system, safeguarded by Breguet’s parachute shock protection. Encased in 18K gold with a 55 mm diameter, the watch bears the signature “Breguet et Fils” on the dial and “Breguet No. 217” engraved on the movement plate.

Divergent Designs: Mechanically Distinct EOT Watches – 1794–1817

Breguet No. 1 (c. 1794)

At the turn of the 19th century, Breguet’s pursuit of mechanical innovation extended beyond escapements and power management to increasingly sophisticated mechanisms, particularly in the refinement of the EOT complication evident in No. 1 of Series 2 and No. 1226.

The Breguet No. 1 of Series 2 marked an evolution in his EOT designs by integrating this function alongside a full calendar. Although initiated before 1794, the watch was completed only in 1819.

Housed in a 63 mm case, it features secondes d’un coup, a jumping seconds mechanism that enhances timekeeping precision. Its Earnshaw spring detent escapement, combined with a three-armed compensation balance and parachute suspension, optimises both accuracy and shock resistance. A helical steel balance spring with terminal curves further improves isochronism, while a reversed fusee and chain regulate power delivery, ensuring stable performance over extended use.

Breguet No. 1, 2nd series (ca. 1794). Image – The Art of Breguet, George Daniels.

The white enamel dial prioritises clarity, featuring a subsidiary seconds display at the bottom, the date on the left, and the EOT on the right. A month aperture at twelve o’clock and a date hand pivoted at ten o’clock complete the calendar indications.

Notably, this was the first instance where the EOT hand, positioned at two o’clock, was driven by a substantially sized negative cam mounted on the annually revolving calendar wheel. The lever and its feeler traced the inside of the cam’s profile, transmitting precise equation corrections. This layout streamlined the display of three complications, date, month, and equation, but increased the watch’s thickness, limiting its suitability for later adaptations.

Dial side view of movement of Breguet No. 1, 2nd series (ca. 1794) and its oversized negative EOT cam. Image – The Art of Breguet, George Daniels

Levers at the edge of the movement allows for manual adjustment of the month wheel and equation, as well as stopping the central seconds hand. While the date hand advances automatically, it halts on the thirtieth day, requiring a manual reset to the first via a designated lever.

Movement view of Breguet No. 1, 2nd series (ca. 1794). Image – The Art of Breguet, George Daniels

Despite its unconventional design, No. 1’s equation system exemplifies Breguet’s approach to balancing innovation with legibility. Subsequent adaptations refined its functionality, allowing for greater flexibility in case dimensions and dial configurations. This iterative development is evident in No. 1226, which, though completed later, was sold two years before No.  1.

Breguet No. 1226 (c. 1817)

Completed in 1817, No. 1226 is a timepiece that displays both mean and solar time on separate dials, an exceptionally rare feature among Breguet watches if we exclude the Fatton inking chronographs.

Retaining the negative cam-and-lever system introduced in No. 1, this watch returns to a conventional-sized format, albeit with a fixed cam, while applying the equation of time indication to a centrally positioned hand on the reverse dial. However, in the accompanying image, the EOT hand is incorrectly displaced relative to the calendar hand’s position. It should accompany the calendar hand, deviating positively or negatively by a maximum of 15 minutes throughout the year.

Breguet No 1226 (ca. 1817). Image – Museu Medeiros e Almeida, Lisbon

The watch is housed in a gold case approximately 60 mm in diameter, featuring finely executed engine-turning. The front gold engine-turned dial displays hours, minutes, and seconds, along with a 36-hour power reserve indication. The reverse platinum dial incorporates a highly detailed calendar system, including indicators for the months, moon phase, day of the week, and date, as well as an EOT scale with a gold sun-adorned serpentine hand.

Breguet No 1226 (ca. 1817). Image – Museu Medeiros e Almeida, Lisbon

At its core, No. 1226 is regulated by a double-wheel Robin escapement, a hybrid system that combines elements of lever and detent escapements. The movement features a three-arm compensation balance, a spiral steel balance spring with a terminal curve, and a parachute suspension system. Additionally, the watch is equipped with a quarter-repeating function with a dumb mechanism, producing softer chimes for discreet use.

Breguet No 1226 (ca. 1817) movement, dial side, with the fixed negative EOT cam at its centre. Image – Museu Medeiros e Almeida, Lisbon

Breguet No. 1226 was purchased by Jean-Andoche Junot around the time he assumed command of the Napoleonic French forces in Portugal, where his early victories earned him the title of Duc d’Abrantes. However, after falling from favour, Junot died in 1813 from injuries sustained in a suicide attempt. His widow, Laure, known for her political manoeuvring and nicknamed “Petite Peste” by Napoleon, later sought the return of the Bourbons, possibly funding her efforts through the sale of the watch, an act unlikely to have pleased the ex-Jacobin Breguet.

The next known owner was William Noel Hill, Baron Berwick of Attingham, a British diplomat and close associate of General Rowland Hill, who later passed it to Arthur Wellesley, 1st Duke of Wellington. This transfer could have taken place after the withdrawal of the army of occupation in 1818, when Hill served as Wellington’s second-in-command, or in 1842 when Wellington succeeded him as General Commanding-in-Chief.

Eventually, No. 1226 entered the collection of the Portuguese collector Medeiros e Almeida in 1964 when he acquired it at auction for a then-record sum of £27,500 (approximately US$700,000 today). It is now housed at the Museu Medeiros e Almeida, where it remains a key piece in the institution’s horological collection.

Refinement and Standardisation: The Evolution of Subsidiary EOT Displays – 1827–1836

Following Breguet’s death in 1823, his workshop, under the direction of Antoine-Louis Breguet, continued refining the equation of time indication, preserving the principles and precision that had defined his legacy.

This period saw all EOT watches with subsidiary indications adopting the display at six o’clock, solidifying a design approach that would become increasingly standardised. The timepieces in this category, spanning from 1827 to 1836, exemplify not only advancements in mechanical execution but also the diversification of Breguet’s clientele, extending from aristocrats and industrial magnates to European monarchs.

Breguet No. 4214 (c. 1827)

No. 4214, sold in 1827 to Captain Richard Seymour-Conway, 4th Marquess of Hertford, for 7,800 francs, represents a key evolution in Breguet’s approach to the equation of time. The gold engine-turned case, measuring 41 mm, is decorated with an intricate map of France, covered in translucent enamel and encircled by a laurel wreath, underscoring its aristocratic ownership.

Breguet No. 4214 (ca. 1827) Half-Quarter Repeater, 7.5 minutes

This watch integrates a half-quarter repeating mechanism and an EOT display into a compact yet highly functional design. The movement incorporates a jewelled lever escapement, a compensation balance with parachute suspension, and a spiral steel balance spring with a terminal curve and regulator—features that reinforce both precision and resilience.

The silver dial features an eccentric chapter ring with Roman numerals, a jumping hour hand and symmetrically arranged subdials, one for the months on the right and one for seconds on the left. Additional apertures display the day of the week, the date, and the moon’s age and phase at the centre. A power reserve indicator sits above the main display, while the equation of time scale is positioned below.

Breguet No 4214 (ca. 1827). Image – Breguet (1747-1823) by Sir David Salomons

The equation function operates via an annual rotating cam that regulates a pivoted lever, translating the variation in solar time into the movement of the equation hand along the display scale. This allowed the wearer to manually adjust time according to a sundial, compensating for the natural fluctuations between mean and solar time throughout the year.

Breguet No. 4308 (c. 1827)

Sold in 1827 to King George IV for 9,650 francs, No. 4308 stands apart as a rare example of a half-quarter repeating montre à tact with an EOT display. This design allowed the wearer to determine the time either visually or by touch, a feature that had been an important element of Breguet’s montres de souscription since the late 18th century.

Breguet No. 4308 (ca. 1827) Half-Quarter Repeating Montre à Tact

The outer, engine-turned gold case features touch pieces and a revolving tact hand, while the inner case houses a sliding mechanism that activates the repeater.

Breguet No 4308 (ca. 1827). Image – Watches & Clocks in the Sir David Salomons Collection, George Daniels & Ohannes Markarian

The silver, engine-turned dial includes an eccentric chapter ring with Roman numerals, subsidiary dials for seconds, days of the week, and months of the year, and apertures for the date and regulator. Below the main dial, a finely calibrated equation of time scale enables precise solar time adjustments. The movement employs a lever escapement, a compensation balance with parachute suspension, and a spiral balance spring with a terminal curve and regulator.

Breguet No 4308 (ca. 1827). Image – Watches & Clocks in the Sir David Salomons Collection, George Daniels & Ohannes Markarian

No 4308, movement, dial side, with EOT cam engraved with the months of the year visible on the right @ Watches & Clocks in the Sir David Salomons Collection, George Daniels & Ohannes Markarian.

King George IV’s patronage further underscores Breguet’s prominence among European royalty, while the watch’s later inclusion in Sir David Lionel Salomons’ collection highlights its enduring historical significance.

Breguet No. 3832 (c. 1828)

No. 3832, delivered in 1828 to Comte d’Archinto for 8,000 francs, represents a refinement in both precision and presentation.

The watch is housed in a 53 mm double-case design with an à tact hand and touch pieces on the outer case, allowing time to be read by feel. The inner case features a slide that activates the half-quarter repeater mechanism, which chimes hours, quarters, and an additional strike at the half-quarter interval.

Breguet No. 3832 (ca. 1828) Half-Quarter Repeater with Calendar and À Tact Feature. Image – Christies

Breguet No 3832 (ca. 1828). Image – Christies

The engine-turned silver dial is arranged for optimal readability, featuring an eccentric mean time chapter ring, a serpentine equation hand positioned on the EOT sector, and subsidiary dials for months and days of the week.

The EOT mechanism relies on a cam-and-lever system, with a pivoted lever tracking the cam’s profile and transmitting the correction via a rack and pinion system to the equation hand. The addition of a full calendar alongside the EOT display reflects the increasing focus on astronomical precision during this period.

The movement includes a jewelled lever escapement and a compensated balance, ensuring stability across temperature variations.

Breguet No. 4254 (c. 1828)

Watch No. 4254, sold in 1828, represents another advancement in EOT integration within a half-quarter repeating format. This watch maintains the same fundamental principles as No. 4214 but introduces refinements in mechanical efficiency and dial legibility. The equation indication, regulated by an annual cam, provides a real-time correction that is easily readable, allowing the wearer to apply the necessary adjustment for solar time.

Breguet No. 4254 (ca. 1828) Half-Quarter Repeater. Image – Breguet (1747-1823) by Sir David Salomons

The gold case features an eccentric chapter ring with subsidiary dials for seconds, the month, and a calibrated sector for the EOT. Additional apertures display the day of the week, the age and phase of the moon, and the date of the month. The repeater mechanism chimes the nearest 7.5-minute interval with clarity, reinforcing its dual function as both an astronomical instrument and a practical timepiece.

Breguet No. 4290 (c. 1829)

No. 4290, sold in 1829, marks one of Breguet’s early forays into ultra-thin designs incorporating an EOT complication.

While few details are available regarding its movement architecture, the watch is known to integrate an EOT display in a highly refined layout, optimising space efficiency while maintaining accuracy. This model serves as a precursor to later ultra-thin equation watches, balancing mechanical sophistication with elegant proportions.

Breguet No. 4290 (1829) Ultra-Thin Equation of Time Watch. Image – Musée national suisse

Breguet No. 4290 (1829) Ultra-Thin Equation of Time Watch. Image – Musée national suisse

Breguet No. 4691 (c. 1831)

Sold in 1831 to Lord Henry Seymour Conway for 7,000 francs, No. 4691 represents Breguet’s most advanced ultra-thin equation of time execution. With a case thickness of just 7.7 mm, it embodies a remarkable synthesis of horological complexity and elegant proportions.

Breguet No 4691 (ca. 1831) prior to its restoration. Image – Sotheby’s

The movement is built on garde-temps principles, featuring a gilt brass lever escapement, a compensation balance with parachute suspension, and a spiral balance spring with a regulator for fine timekeeping precision.

Breguet No 4691 (ca. 1831). Image – Breguet

The guilloché silver dial is arranged for intuitive readability, featuring an off-centre mean time display with Roman numerals, subsidiary seconds dial at 9 o’clock, a month indicator at 3 o’clock, and apertures for the day and date. The EOT display, positioned between 5 and 7 o’clock, is marked with a blued steel serpentine hand featuring a gold sun motif. A moon phase display appears above 12 o’clock, while a power reserve indicator is positioned at the bottom. The watch was later acquired by the Breguet Museum in 2013 for US$1.1 million.

Breguet No 4691 (ca. 1831). Image – Breguet

Breguet No. 4517 (c. 1836)

No. 4517, sold in 1836 to Anatoly Demidoff, 1st Prince of San Donato, for 4,000 francs, is an exceptional ultra-thin pocket watch that refines Breguet’s equation of time execution within an elegant and highly compact case. Later part of the Belmont House Collection, it integrates an EOT display, temperature Gauge, moon phase, and annual calendar while maintaining mechanical precision in a remarkably slim form.

No. 4517 (ca. 1836) Ultra-Thin EOT with Moon Phase & Calendar. Image – Belmont House Collection

The engine-turned silver dial features a highly legible layout, with the EOT indication positioned below the main display, ensuring that the correction remains intuitive to read. The movement is built on chronometer principles, incorporating a lever escapement, compensation balance, and parachute suspension. This watch serves as one of the final refinements of the subsidiary EOT display in Breguet’s pocket watches.

The Running Equation: Differential Gearing in Breguet’s EOT Watches – 1805-1814

Breguet’s advancements in horology marked a pivotal shift from mechanically distinct EOT displays to the running EOT mechanism, a breakthrough in precision timekeeping. Early EOT pocket watches relied on discrete mechanical systems, such as cam-and-lever mechanisms, to indicate the difference between mean and true solar time. These designs required a manual calculation, with the wearer referencing a subsidiary display to determine meantime relative to solar time.

Breguet’s ingenuity, however, led to the application and development of the then-already-known running EOT system, where the equation correction was dynamically integrated into the motion work, allowing the displayed time to continuously account for solar variation without requiring user calculation.

By incorporating differential gearing and disengaging mechanisms, these watches applied solar time corrections in real-time, refining astronomical timekeeping while minimising operational friction and improving mechanical efficiency. Today, the running EOT system still represents a pinnacle of technical sophistication, blending horology’s artistic heritage with functional advancements that cater to both scientific precision and practical usability.

Among the most significant examples of Breguet’s innovation in this field are No. 1348, No. 1416, No. 2614, and No. 3862. Each represents a distinct phase in the evolution of differential running EOT systems, exploring variations in disengaging mechanisms, complex calendar integration, and adaptations tailored to the needs of the watchmaker’s international clientele.

Breguet No. 1348 (c. 1805)

Breguet No 1348 (ca 1805) running EOT with disengaging mechanism. Image – Antiquorum

Breguet No. 1348, produced in 1805 and sold to Messrs. Meyer and Tues, introduced a disengaging mechanism designed to minimise wear while ensuring precise solar time adjustments, engaging only once per hour. This innovation reduced unnecessary strain on the movement while maintaining the accuracy of the equation correction.

Breguet No 1348 (ca 1805) running EOT with disengaging mechanism. Image – Antiquorum

The watch also features a dual calendar system, accommodating both the Gregorian and Julian calendars, alongside a sectoral EOT display indicated by a serpentine Breguet hand. Housed in a 62 mm gold case signed by Guillaume Mermillod, No. 1348 remains a significant early example of Breguet’s advancements in disengaging EOT mechanisms.

Breguet No. 1416 (c. 1812)

Breguet No 1416 (ca 1812) running EOT with Half-Quarter Repeater. Image – Sothebys

Breguet No. 1416, produced in 1812 and sold to Prince Antoine de Bourbon, took a similar approach to EOT correction by integrating a half-quarter repeater with a dual-hand display. Instead of relying on a subsidiary dial, the watch employs two minute hands, one for meantime and the other for solar time, allowing for instantaneous visual comparison.

The equation correction is dynamically adjusted via an annual wheel system, and the repeater mechanism, chiming at 7.5-minute intervals, further enhances the watch’s usability, providing both visual and auditory means of tracking time. Now part of the Belmont House Collection, No. 1416 exemplifies an advanced execution of real-time equation correction in a dual-hand configuration.

Breguet No. 2614 (c. 1814)

Breguet No 2614 (ca 1814) Montre Turque with running EOT. Image – The Art of Breguet, George Daniels

Breguet No. 2614, produced in 1814, is one of the rare Montre Turque EOT pocket watches specifically crafted for the Ottoman market. No. 2614 integrates a differential gear system that continuously adjusts for solar time variations in real time, ensuring seamless accuracy.

Breguet No 2614 (ca 1814) Montre Turque with running EOT. Image – The Art of Breguet, George Daniels

Beyond its advanced equation function, the watch incorporates an annual calendar and a lunar display, with a subsidiary dial referencing both Islamic and European calendars, highlighting its dual-purpose design.

Breguet No 2614 (ca 1814) Montre Turque with running EOT. Image – The Art of Breguet, George Daniels

The dial, signed in Turkish script and featuring Ottoman numerals, reflects Breguet’s adaptability to international clientele, demonstrating his ability to tailor complex horology to the specific cultural and technical requirements of different regions.

Dual-Time Clarity: Watches with Separate Solar and Mean Time Dials – 1817-1829

Breguet’s development of the equation of time complication evolved towards greater clarity and mechanical efficiency. Unlike earlier models that employed a concentric running equation hand, this group of watches introduced dual-display designs, separating mean and solar time and applying the differential principle to calculate and display the equation correction. This refinement resulted in a series of significant timepieces that include Nos. 2807 (1817), 3832 (1828), 3862 (1821/24), 3863 (1824), 4111 (1827) and 4112 (1829). Though unified by their astronomical function, each represents a distinct approach to balancing complexity, legibility, and mechanical ingenuity.

Breguet No. 2807 (c. 1817)

Breguet No. 2807 (ca. 1817) EOT on differential with optimized energy efficiency. Image – Antiquorum

Sold in 1817 to Russian General Alexis Petrovich Yermoloff, Breguet No. 2807 introduced a new differential-based EOT mechanism aimed at reducing mechanical strain and optimising energy efficiency. Instead of maintaining continuous engagement with the train, its equation function activates only once every two hours, minimising friction while ensuring precise solar time adjustments. This mechanism operates via a specialised double-wheel and double rack-and-pinion differential system, governed by an equation cam mounted at the centre of the annual wheel, allowing seamless calculation of the discrepancy between mean and true solar time.

Housed in a 53 mm gilt brass case, the movement features a going barrel and a straight-line calibrated lever escapement, ensuring stable timekeeping performance. The dial, crafted by Louis Tavernier (1754–1840), presents a well-balanced layout with separate sub-dials for true solar time and mean time, complemented by complications such as moon phases and a date aperture. Tavernier’s father, Jean-Pierre (1714–1795), had already published a work entitled Table de différence du temps vrai au temps moyen in 1754, reinforcing the family’s deep engagement with astronomical timekeeping.

Breguet No. 3862 (c. 1821-1824)

Breguet No. 3862 (ca. 1821/24) EOT on differential, completed only in the 1960s. Image – Maison Breguet

Breguet No. 3862, started between 1821 and 1824 but left unfinished until its completion in the 1960s, further refined the differential-based approach by integrating a perpetual calendar system. Designed to complete one annual rotation, its equation cam interacts with the differential gearing to continuously adjust the solar time display, ensuring precise and automatic equation corrections throughout the year.

Breguet No. 3862 (ca. 1821/24) EOT on differential, completed only in the 1960s. Image – Maison Breguet

The movement is gilt-finished, featuring a straight-line lever escapement with 21 jewels, a bimetallic compensation balance with straight parachutes on both pivots, a spiral steel spring with a terminal curve, and a steel regulator with a gold index.

The silvered engine-turned dial presents two symmetrical sub-dials: the left displays solar time with Arabic numerals and an applied gold sun symbol above 12 o’clock. At the same time, the right indicates mean time with Roman numerals and an applied gold star symbol. An outer ring is calibrated for the annual calendar, indicated by a central blued steel serpentine hand. Additionally, the watch features a small subsidiary seconds dial, a weekday window, and a fan-shaped aperture displaying moon phases and the lunar calendar.

The case, crafted from 18K gold with an engine-turned finish, measures 61 mm in diameter and includes a numbered and signed gold cuvette. The movement remained incomplete until the mid-20th century, when it was finished with a newly designed dial, moon disc, hands, and case. It is now part of the Montres Breguet collection.

Breguet No. 3863 (c. 1824)

Breguet No. 3863 (ca 1824) EOT on differential à tact. Image –  The Art of Breguet, George Daniels

By 1824, Breguet had further refined the differential EOT system with No. 3863. The silver engine-turned dial of this watch features a sweep centre date hand and two subsidiary dials, with solar time on the left and meantime on the right. Above and separating both dials is a subsidiary seconds indication. Below, two apertures display the moon’s age and phase alongside the day of the week indicated by its first letter. The engine-turned case incorporates an à tact hand on the back and touch pieces along the edge.

Breguet No. 3863 (ca 1824) EOT on differential à tact. Image –  The Art of Breguet, George Daniels

Mechanically, No. 3863 employs a lever escapement, a two-armed compensation balance, a spiral steel spring with a terminal curve and regulator, and Breguet’s signature parachute suspension system for shock absorption. Its EOT mechanism adjusts both the hour and minute hands of the solar time display with minimal resistance, using a double spring-loaded wheel connected via two pivoted racks and a pinion for precise adjustments.

Breguet No. 3863 (ca 1824) EOT on differential à tact. Image –  The Art of Breguet, George Daniels

Breguet No. 4111 (c. 1827)

Breguet No. 4111 (1827) EOT with Half-Quarter Repeater, 7.5 min. Image – Christies

No. 4111, produced in 1827, represents an ultra-thin execution of the differential EOT complication with a dual-dial system. Originally sold to Mr Peyronnet before being resold in 1834 to Count Charles de l’Espine, the watch features a half-quarter repeater that chimes every 7.5 minutes, enhancing its practical utility as an astronomical timepiece. As previous models in this category, it arranges separate off-centre subdials, solar time on the left and meantime on the right, allowing for an intuitive reading of the equation correction.

Built on chronometer principles, its movement incorporates a lever escapement, a compensation balance, and a parachute suspension system for enhanced shock resistance, ensuring reliability despite its slim proportions.

Breguet No. 4112 (c. 1829)

Breguet No. 4112 (1829) EOT with Half-Quarter Repeater, 7.5 min. Image – Watches & Clocks in the Sir David Salomons Collection, George Daniels & Ohannes Markarian

Building upon this lineage, No. 4112 was introduced in 1829, integrating the advancements of its predecessors while also incorporating a half-quarter repeater. Sold to Mr Goding for 8,128 francs, this watch not only displayed the difference between solar and mean time but also made it audible through a striking mechanism that chimed every 7.5 minutes.

Breguet No. 4112 (1829) EOT with Half-Quarter Repeater, 7.5 min. Image – Watches & Clocks in the Sir David Salomons Collection, George Daniels & Ohannes Markarian

Housed in a 56 mm gold engine-turned case, it features a crystal cuvette, offering a clear view of the movement. A centrally placed equation cam governs solar time corrections through a precise lever mechanism. At the same time, additional complications include a leap year cycle, an age and phase of the moon display, and a fast/slow regulation indicator at 6 o’clock.

Breguet No. 4112 (1829) EOT with Half-Quarter Repeater, 7.5 min. Image – Watches & Clocks in the Sir David Salomons Collection, George Daniels & Ohannes Markarian

Conclusion

Breguet’s EOT watches mark a significant chapter in the development of mechanical horology, showcasing his ability to tackle complex astronomical indications with clarity and ingenuity. He treated such complications as serious technical challenges, integrating them into functional instruments that served both scientific and practical purposes.

These creations reflect the maturity of late 18th- and early 19th-century watchmaking, and they helped establish mechanical solutions to celestial problems as a legitimate pursuit within the field. The influence of these pieces remains visible in modern horology, where the equation of time continues to be explored as a mark of technical refinement and historical awareness.

Breguet’s contribution thus stands as a benchmark in watchmaking—where intellectual rigour, mechanical skill, and purpose-driven design converged to advance the discipline.

Sources and Bibliography

Primary sources

● Breguet Official Website:
○ For information on Breguet’s history, innovations, and some watch models. (www.breguet.com)
● Musée du Louvre, Paris:
○ For access to Breguet timepieces and related historical documents.
● Musée des Arts et Métiers, Paris:
○ For information and images of Breguet No. 92.
● L.A. Mayer Museum for Islamic Art, Jerusalem:
○ For information and images of Breguet No. 160.
● Museu Medeiros e Almeida, Lisbon:
○ For information and images of Breguet No. 1226.
● Christie’s Auction House:
○ For auction records and images of Breguet No. 217 and No. 4111.
● Antiquorum Auctioneers:
○ For information and images of Breguet No. 2807.
● Montres Breguet S.A. Collection:
○ For information and images of Breguet No. 3862.
● Sir David Salomons Collection:
○ Historical documentation and information about the watches within this collection.

Secondary sources

● Daniels, George. The Art of Breguet. London: Sotheby Parke Bernet Publications, 1975.
○ Essential for information on many of the Breguet watches discussed.
● Engel, Thomas. A.L. Breguet, Watchmaker of Kings. London: Sotheby’s Publications, 1994.
○ Provides detailed historical context and analysis of Breguet’s work.
● Clutton, Cecil, and George Daniels. Watches. London: B.T. Batsford Ltd., 1965.
○ A classic horological reference with information on Breguet.
● Daniels, George, and Ohannes Markarian. Watches & Clocks in the Sir David Salomons Collection. London: Sotheby’s Publications, 1980.
○ Provides information about the watches that were once owned by Sir David Salomons.

While the invention of the spiral hairspring by Christiaan Huygens in 1675 kickstarted a revolution in terms of portable precision timekeeping, the concept was far from fully developed. It was arguably only with the later invention of the overcoil hairspring that the ideal oscillator in portable watches emerged.

For many years horologists — theoreticians and artisans alike — worked to perfect the balance-hairspring assembly to optimise its performance, notably in terms of isochronism. True isochronism became a sort of holy grail for watchmakers all around the world, who all sought to ameliorate the inherent quirks of the sprung oscillator.

The recent Breguet Soucription features an overcoil hairspring of non-magnetic Nivachron alloy

The need for end curves

The quest for isochronism was a true challenge for horologists. Isochronism is the ability of the balance-hairspring assembly the have the same period of oscillation for small and large amplitudes alike. In other words, the balance oscillation takes the same period of time regardless of the degree travelled.

This is very important, since a balance usually swings with high amplitude with a fully wound mainspring and then runs at progressively smaller amplitude as the barrel unwinds. As a timepiece is required to keep good time regardless of  its winding state, an oscillator whose period is independent from its amplitude is needed. (Another solution to this is to optimise the energy delivery from the mainspring with a constant force mechanism, which is another topic entirely.)

Huygens’ drawing of an early hairspring embodiment

The balance-hairspring model is theoretically isochronous — but only on paper with ideal conditions assumed. In practice friction and slight equilibrium defects can disrupt the oscillator’s ideal running, making the timepiece’s accuracy dependent on the state of winding. 

A large issue that was noticed early by watchmakers was the uneven development of the hairspring. This happens due to a geometrical constraint of the system, with the fixed outer pinning point not allowing the hairspring to “breathe” concentrically. We explained this a little more in our piece on the Ulysse Nardin Freak and the development of the silicon hairspring. 

The uneven development of the hairspring harms the oscillator in two distinct ways: the eccentric movement of the coils displaces the spring’s center of gravity away from the balance’s axis, creating a disequilibrium and the uneven development strains the pivots because the coils apply unwanted side pressure to the axle. 

The displacement in the centre of gravity was found to be negligible, since it tends to virtually cancel out during two alternations — so the net centre of gravity vector displacement over one full oscillation is not really a concern. 

The torque directed onto the pivots however is the larger issue, since the pivots themselves distribute that force into their jewels, increasing friction and creating wear patterns in time. This pressure can’t be cancelled out and the generated friction force actively disrupts the oscillator’s isochronism.

A logical solution to this would be to force the hairspring to develop concentrically so that the residual couple applied to the inner pinning point — thus to the pivots — would be as close to zero as possible. This is where end curves come into play.

An overcool in the Lange Zeitwerk L043.3

A short history of end curves

As early as the 17th century a French watchmaker by the name of Gourdain used a sort of courbes tâtées  — literally “touched” (or more accurately, “corrected”) curves. Empirically formed by the artisan, these curves seemed to improve the balance spring’s “breathing”.

A great breakthrough later came from John Arnold (1736-1799) who shaped the ends of his cylindrical hairsprings into sharp inward curves connecting the spring ends to the balance collet and the upper bridge pinning point respectively. 

Modern cylindrical hairspring in a Moser tourbillon

Abraham-Louis Breguet (1747-1823), a friend of Arnold’s, borrowed from his work and adapted the Englishman’s end curves to flat balance springs — giving birth to the Breguet overcoil. The talented watchmaker noticed that raising the last coil of the hairspring into a plane parallel to the other coils and curving it slightly towards the outer pinning point made the spring “breathe” concentrically. 

Edouard Phillips

These early overcoils were empirically shaped by watchmakers, who adjusted and bent the curve as they saw fit after observing how the timepiece performed over a period of time. There was no rigorous theory involved in forming the end curves and watchmakers didn’t have a definitive explanation for how and why the method worked. 

This is where the French engineer and mathematician Edouard Phillips (1821-1889) stepped in and assembled a rigorous mathematical theory of end curves — which still stands as a reference today. 

By trade Phillips was a “mine engineer” who focused on material and structure sciences. He developed his own theories on blade springs of different geometries and the torques they could provide. During his lifetime he was chair of mechanics at the prestigious École Polytechnique and a member of the Académie des sciences. 

During the latter part of his life, Phillips dedicated himself to the study of horology, more precisely to the study of the hairspring — a particular embodiment of a blade spring, after all. In 1860 he published a groundbreaking paper, Mémoire sur le spiral réglant des chronomètres et des montres, where he studied the behaviour of an end curve. Phillips concludes by giving some rules for shaping an ideal hairspring, which are now known as “Phillips conditions”. 

Extract from E. Phillips’ “Mémoire sur le spiral réglant des chronomètres et des montres”

The outer end curve

In his paper Phillips started out by assuming the uneven development of coils exerts some torque on the pivots. Then he started out mathematically exploring what would cancel out that unwanted torque. 

Through a lengthly process involving integral calculus, he applied his own theories of elasticity to the hairspring model and came up with a method of keeping the spring’s coils centred on the balance’s axis. The conditions he found gave birth to the Phillips end curve — a perfected overcoil which reduces the lateral pivot pressure to the point of virtually canceling it out.

The Phillips conditions for overcoils can be summed up in a few words and a short mathematical expression:

The centre of gravity of the terminal curve has to be placed on a radius perpendicular to the line joining the spiral’s centre of gravity and the point where the curve breaks off from the spiral. The distance of the curve’s centre of gravity to the spiral’s centre of gravity needs to be equal to the spiral’s radius squared, divided by the length of the end curve. 

The concept might seem complicated but is straightforward enough to implement in real hairsprings. The figure below may be more suggestive for grasping the proportions. The starting point of the overcoil A is coincident with axis Ox. The gravity centre G of the end curve sits perpendicular to that axis, on Oy.

Interestingly, Phillips’ condition doesn’t mandate any sort of particular geometry of the overcoil; as long as the equation is satisfied the end curve can take on any shape. This explains why different brands and watchmakers use slightly different overcoil geometries. Phillips also noticed that the overcoils were more effective for larger hairsprings. 

Common shapes of overcoils

One of the simplest types of overcoils (which satisfies Phillips’ equation) is the circle arc end curve. The plain shape breaks off from the spiral and arches towards the pinning point. The curve is uniform and circular while the arc it describes is fairly short. Below is figure by L. Defossez, detailing the particular geometry of such a curve. 

Overcoil made of one circle arc. Image – L. Defossez

Other overcoils are made of two circle arcs of different radiuses, giving the final curve an elongated shape. Some movements with a spring regulator use this geometry, as the second arc’s centre coincides with the spring’s centre and a traditional raquette can be employed.

Overcoil made of two circe arcs with different radiuses. Image – L. Defossez

An early 20th century Patek Philippe pocket watch movement with a classic high-end chronometer hairspring set up

Today most brands use a simpler geometry, that of two circle arcs linked by a straight segment. Compared to the purely circular end curve, this shape is easier to bend. Variations of this geometry can be seen in industrially manufactured movements from the likes of Rolex or IWC. 

Overcoil model with two circle arcs joined by a segment. Image – L. Defossez

The MB&F LM QP movement sports a very prominent overcoil

Straight terminal curve which satisfies Phillips’ condition. While theoretically sound, such an overcoil was never used to the author’s knowledge. Image – L. Defossez

The inner (or Grossmann) curve

Edouard Phillips based his studies on helical springs, which would feature two symmetrical curves, one joining the outer pinning point and the other the inner pinning point. This model does not fit entirely with flat springs, which have different diameters for their outer and inner ends. 

Voutilainen tourbillon movement with a hairspring featuring an inner Grossmann curve.

While overcoils may counteract most of the uneven development of the hairspring, reducing the side pressure on the pivot, some argue the innermost coils of the spiral have their own destructive effect as they unwind against the collet. 

The collet is the piece which joins the hairspring with the balance staff. Of circular shape, the collet has its own interactions with the inner coils of the hairsprings, which can exert some side pressures that the overcoil can’t cancel out. 

Jules Grossmann, a respected regleur from Le Locle, found Phillips’ discoveries consistent with his own extensive experience and observations adjusting overcoils. While he recognised the utility of calculus, he could not truly comprehend nor entirely follow Phillips’ methods. The subject stated with him nevertheless. 

Even in chronometers using theoretically perfect overcoils, Grossmann still noticed some running differences between horizontal positions — issue which he addressed by enunciating a set of attach point rules. These rules concern how many full turns a hairspring has and where the inner pinning point sits, relative to the outer pinning point. 

Grossmann also learnt at some point calculus all by himself, using available courses and books on the subject. Using his newly-acquired knowledge, Grossmann adapted Phillips’ theory on the inner end of flat hairsprings, creating the inner — or Grossmann — curve. This adjustment of the inner spiral seeks to cancel out any side pressure from the innermost coils of the hairspring.

Edouard Phillips eventually payed a visit to Jules Grossmann in Le Locle in 1871. The two horologists remained in contact until Phillips’ death in 1889. In his latter years Grossmann wrote an extensive, 450-page volume about precision watch regulation, Théorie du reglage. 

The practical utility of the inner curve is still debatable. George Daniels suggests in Watchmaking that “due to the difficulty of forming so small a curve accurately the results are uncertain”. He is indeed right, as Grossmann inner curves are very difficult to execute, requiring the hand of a highly skilled watchmaker.

Hairspring with both an outer Phillips overcoil and inner Grossmann curve. Image – L. Defossez

Inner curves are a rare find, with Voutilainen being one (if not the only) watchmaker to employ Grossmann curves consistently across his movements. The Vingt-8 series of calibers comes with a large balance, complete with a hairspring with both a Phillips overcoil and Grossmann inner curve. 

Makers using silicon hairsprings also seem to implement a kind of inner curve, which is easy to obtain with an etching process that can accommodate any kind of planar geometry. 

The Voutilainen Vingt-8 balance

Conclusions

The subject of overcoils and terminal curves remains a quite a fascinating topic for horologists. While the first solid theory of overcoils is over 160 years old, new technologies make way for novel end curve types which were inconceivable during Phillips’ time. De Bethune employs a proprietary hairspring, made of two separate pieces, one for the spiral and the other for the flat end coil. De Bethune claims the device performs as well as classic overcoils.

Manufacturers of silicon hairsprings have been employing specialised terminal curves since the beginning. While their approach is different from the likes of Edouard Phillips or Jules Grossmann, today’s engineers are experimenting with intricate geometries and new materials in crafting isochronous springs with little effort. The downside of these advancements is that traditional hand adjusting of end curves is becoming an increasingly rarer skill.