The Tourbillon and why it still matters

By A Collected Man

The tourbillon occupies a special place within the pantheon of horological complications. Since its inception over two centuries ago, it has taken different forms, from the overly restrained, classic approach, to the opulently displayed and technically innovative one. Regardless of its execution, no other complication has captivated the imagination of both collectors and watchmakers in quite the same way.  

It is possibly one of the most aesthetically pleasing and easy to grasp, at least on a visual level, complications of all. As the cage regularly rotates at a steady pace, it appears to be doing everything and nothing at the same time. It seems complex, yet simple.

Of course, it’s not just the visual appeal of the tourbillon which has generated the fascination which it enjoys today. Its history is unique in watchmaking, with a single, unarguable point of origin and an evolution over time full of intriguing details. As some may already know, it was invented by Abraham-Louis Breguet in 1795 and patented in 1801. No one before him had conceived of such a device and it would be some time before anyone could improve on it. In fact, it would take Breguet himself an additional four years to produce his first commercial project housing a tourbillon.

 

Three tourbillon watches showing the progression of the complication over time

The progression of the tourbillon, from an unsigned pocket watch movement to the complexity of a Richard Mille RM021.

 

It is only in recent times that the tourbillon has become so wildly popular. When it rose to prominence in wristwatches at the turn of the century, it became the benchmark for any watchmaking brand that aspired to be regarded as haute-horologerie. It is also considered a training ground for young watchmakers seeking to prove their worth to the world, with François-Paul Journe being a recent example from the last few decades. For many, it is synonymous with complication. Let’s try to figure out how we got here.

How does it actually work?

 

Many will undoubtedly be aware of what a tourbillon looks like while it’s functioning. The rotating cage, housing a pulsating balance wheel, is a familiar sight. In essence, its singular purpose is all about improving accuracy.

The escapement and balance wheel, two core components at the heart of the watch, are especially sensitive to external disruption, such as shocks, magnetism or moisture. A particularly salient issue is gravity, which can disrupt timekeeping by pulling these components downwards. The effects of gravity are worsened when the timekeeping device is kept in a stationary position, therefore making the disruption more consistent.

This is an especially relevant issue in clocks, which by their very design don’t move, or in pocket watches, which often remain in the same position when stored in a pocket. Despite a wristwatch being worn on the wrist, and therefore remaining in motion, this disruption remains problematic. Indeed, our wrist often finds itself adopting similar positions, whereby gravity can pull down on the core components and affect timekeeping.

 

George Daniels Blue tourbillon wristwatch shot by A Collected Man London
The tourbillon cage inside the F.P. Journe Tourbillon Souscription shot by A Collected Man London

Two refined examples of modern tourbillons in wristwatch form, from George Daniels and Francois-Paul Journe. 

 

In a tourbillon, the escapement and balance wheel are mounted within a rotating cage, the purpose of which is to counteract the disruption caused by gravity. In essence, the regular rotation of the tourbillon cage is intended to average out any positional errors and maintain greater accuracy.

It may sound relatively simple, but the execution is rather more complicated. Whilst we could do try to explain how it all comes together, we thought it best to leave this in much more capable hands. As such, we asked none other than Stephen Forsey, one half of Greubel Forsey and a master of complicated watchmaking, to shed some light. As he puts it,

“You have the escapement and the balance wheel all mounted together, on a rotating platform that is driven by the movement to rotate in a regular cycle. So, the idea is that your watch is moving in space in real time.

How does it do that? You have a planetary gear on the escape wheel and you have what’s called the fixed wheel. On a normal watch, you might have a small seconds hand that turns once a minute. So, in a tourbillon, that wheel is fixed to the plate, and because you drive the escapement platform, the only way it can turn is by the escape wheel moving around that fixed wheel.”

Essentially, the rotation of the tourbillon cage is entirely driven by an additional gear, which is attached to the escape wheel. The escape wheel works its way around the edge of this fixed gear, generating the rotation. This means that the power being released from the mainspring is not only driving the movement of the watch, but also simultaneously rotating the cage.

 

An early Girard-Perregaux three bridges tourbillon movement

An early creative take on the architecture of a tourbillon movement, courtesy of Girard-Perregaux, with this design still in use today.

 

This is where things become complicated. A consistent struggle for those trying to make a tourbillon comes from ensuring that the power generated from the mainspring is sufficient to create motion of the cage, while staying regular enough to keep accurate time. Over the centuries, this process has become simplified with the advent of technology and design software, but it was not always this way. Designing, creating and regulating a tourbillon along more traditional methods, remains no small feat.

The Breguet Origin

 

The claim to inventing the complication is not a disputed one, as with many other things in horology. It can be pinpointed to one watchmaker: Abraham-Louis Breguet. Born in Neuchâtel, then a Prussian principality, Breguet would go on to pioneer significant technical and aesthetic innovations during his career, with his influence carrying through to the present day. It is no coincidence that he remains the most cited reference point for accomplished watchmakers centuries later, from George Daniels to François-Paul Journe.

First invented in 1795, the patent for the tourbillon was granted in 1801. After that, tracing its evolution becomes slightly more complicated. Breguet did not manage to sell a tourbillon for another four years, due to the complexity of putting together the complication, although it is believed that he gifted two between 1801 and 1805.

Though unconfirmed, it is believed that the first two tourbillon movements were adapted movements from John Arnold, a contemporary and close friend of Breguet's, hence why he did not sell them on as completed commercial projects. The complexity of constructing such a movement is also demonstrated in the fact that Breguet only managed to make thirty-five in his lifetime, of which only ten are known to exist today.

 

Drawing of the the first tourbillon from Abraham-Louis Breguet

One of the first drawings Breguet produced of his tourbillon, courtesy of Institut National de la Propriété Indistruelle in Paris.



There is more than meets the eye when it comes to Breguet’s tourbillon. The watchmaker was producing and developing these in the infancy of the lever escapement. For those unaware, the escapement is one of the crucial components of a timekeeping device, involved in delivering energy to the movement. It gives impulses to the timekeeping element and periodically releases the gear train to move forwards, advancing the hands. Perfecting the escapement of a watch has been one of the principal pursuits of watchmakers for centuries, with the most recent example being George Daniels, with his now celebrated co-axial escapement.

As Alex Barter, the previous Head of the Watch Department at Sotheby’s, and author of The Watch: A Twentieth-Century Style History tells us “Breguet used a range of escapements in his tourbillons, from the Peto Cross detent, an early lever escapement, to his own natural escapement.” The fact that Breguet was experimenting with different types of escapement shows just how exploratory the first tourbillons were. 

As previously mentioned,the first two tourbillon watches he produced, No. 22 and 169, both started life as John Arnold movements. An English watchmaker of great renown, Arnold also had a lasting impact on watchmaking, pioneering several advances, such as the invention of the overcoil balance spring, which is still to be found in most mechanical wristwatches to this day.

In combination, Breguet and Arnold are viewed by many as having birthed the modern mechanical watch. Both men shared a close personal relationship. No. 169 was later gifted to Arnold’s son, who spent two years apprenticing under the Swiss watchmaker. Breguet often used his own échappement naturel, or natural escapement, from the 5th or 6th piece onwards, according to Barter.

 

Abraham-Louis Breguet's No. 1188 tourbillon pocket watch

Breguet's No. 1188 showing the just how well preserved these early tourbillons can be.

 

From the early 1800s, through to the next century, the use of tourbillons was limited to observatory trials and high-paying clients, in no small part due to the immense skill and time it took to construct one. “It’s not easy to make a tourbillon” Forsey tells us, “and when you consider the rudimentary tools that Breguet was using at the time, it makes his first watches even more remarkable.”

 Thanks to the advancements being made in the lever escapement and the relative imprecision that the tools of the time afforded watchmakers, it was often more cost effective to create a pocket watch with a decent lever escapement than a tourbillon. This is why it is estimated that between 600 and 900 tourbillons were made from 1801 to 1945. That’s less than seven a year. Today, it’s certainly possible that more tourbillons are made within a single year than were produced over that century and a half. 

Rather than covering an extensive range of Breguet’s pieces, we thought we would dig deeper into a single one, which truly brings to life what was so remarkable about his work.

Possibly one of the most important early Breguet tourbillons has recently resurfaced, due to go under the hammer at Sotheby’s, in London. It has been over 20 years since it was last seen publicly and it is known as No. 1297. It is significant for a number of reasons, not least of which was its original owner, King George III of England. While he might be better known as Mad King George thanks to the Alan Bennett play, he was in fact the first king to receive a formal education in topics ranging from the sciences to the arts, and he would become a strong supporter of both in his time as monarch.

 

The side and back of the case of King George III's watch made by Breguet

The razor sharp engraving of King George III's 200 year old watch.

 

Another reason this watch is so significant, both to the history of Breguet and the tourbillon, is that it is believed to be the first commercially sold tourbillon Breguet produced. After pieces one and two were given away as gifts, this was the first one made for a paying client. Not the worst of first clients either. 

Barter is keen to point-out just how historically significant it is that this client was the King of England, as the Napoleonic Wars were still raging and there was a ban on goods being traded with France’s enemies. This may go some way to explain the odd and interesting wording which appears on the watch. Indeed, all of the text is in English, as King George III was a native English speaker, unlike his grandfather King George II.

 

Macro shot of the tourbillon cage and platform of the King Geogre III's watch made by Breguet
Macro shot of the tourbillon cage of King George III's watch made by Breguet

 The only mention of the man who made this watch is subtly engraved on the tourbillon platform. 

 

As a result, this tourbillon features a rather curious translation of “Régulateur à Tourbillon” on the dial, where it instead reads “Whirling About Regulator”. Considering there has never been a translation of tourbillon into English, and that this one was picked by Breguet himself, it may just be the most valid. We certainly think it could be brought back.

Another noteworthy feature of this watch is the escapement Breguet chose for it. The Robin escapement, a hybrid of the lever escapement and the chronometer escapement, was invented by Robert Robin in 1792 and worked via a single impulse in one direction. This was an escapement that Breguet had used before, however, this would be the only time it would appear in one of his tourbillons.

An interesting point that Barter brought to our attention is that George Daniels’ book The Art of Breguet doesn’t mention this watch anywhere, nor does it mention a tourbillon made by Breguet with a Robin escapement. This is despite the fact that the watch, as well as notes made by King George III on the watch, were displayed at an exhibition in 1955 called Five Centuries of British Timekeeping, held at Goldsmiths’ Hall. Considering Daniels’ book was published some twenty years later, it’s unclear why this piece was not included.

 

Breguet's translation of the word tourbillon on the dial of King George III's watch
The common seconds sub-dial on King George's III's watch made by Breguet

All the wording on the watch is in English, especially for the King of England, with a few rather curious translations. 

 

Barter highlights the layout of this model as being rather important, considering it marked the beginning of what he calls “possibly the first serially made tourbillons.” Between 1808 and 1815, Breguet made a series of four-minute tourbillons, with the same dial configuration and a much slimmer movement than any that came before. All tourbillons created since owe a debt to these early models. 

While Barter points out that the numbers on these models is in no way sequential — working out Breguet’s numbering system is no easy task — they all appear to be made one after another, based on a very similar design. While the King George III piece is the only one to house a thermometer, it could be argued that it still belongs to this series, which George Daniels first highlighted in his aforementioned book.

The watch will be going up for auction on July 14th at Sotheby’s in London, which will actually be the second time it has come under the gavel at the auction house. In November 1999, it hammered for £551,500. A rather considerable sum. Barter was still working at Sotheby’s at the time and distinctly remembers how clean and crisp the detailing and finishing is on the watch. As he puts it, “it’s practically like new, you could cut yourself on the engine turning on the back it’s so sharp.”

 

The hand construction of the a tourbillon cage at Greubel Forsey

The tradition of hand making a tourbillon cage is being kept alive by a select few craftsman. 

 

The story of the tourbillon does not stop with Abraham-Louis Breguet’s death in 1823. Not only was one of his first tourbillons sold by his son after his death, but the brand that bears his name continued creating his inventions through to the modern era. In fact, Breguet were actually one of the first brands to introduce the tourbillon back into the wristwatch. More on that later on.

The Great Rivalry of the Tourbillon and the Carousel

 

As the tourbillon required significant skill, not only to produce its delicate components but also to adjust it to function properly, other watchmakers started to look for easier alternatives which still produced similar results. Enter Bahne Bonniksen, a Danish watchmaker working out of Coventry, England in the late 19th century. In 1892, Bonniksen invented the Karrusel, otherwise known as the carousel. While at first sight it may appear to be the same as a tourbillon, it operates according to very different mechanics. 

“The difference between a tourbillon and a carousel”, Forsey explains, “is that the part of the mechanism that drives the tourbillon is part of the gear train. But in a carousel, you have a branch that drives the escapement through a planetary gear, but it drives it like a platform, and then you have another branch that makes the whole platform rotate.”

In essence, by sitting the escapement on a rotating platform, you still counteract the effect of gravity on the balance spring, but the same level precision is not needed in the manufacturing process, as there is no cage balanced on a pinion. It goes to show just how forward-thinking and skilful Breguet was, that following the invention of the tourbillon, the immediate reaction of many watchmakers was to take a less challenging approach.

 

A Bonniksen karrusel watch next to an early tourbillon pocket watch

Here you can see an original Bonniksen Karrusel pocket watch (left) next to an early tourbillon (right). 

 

This form of gravity correction proved to be massively popular, especially with British watchmakers. So much so, that out of the fifty-two watches which obtained the highest marks at the Kew Observatory trials in 1902, forty of them either contained a tourbillon or a Karrusel movement. This large-scale adoption of Bonniksen’s movement was only possible thanks to his encouragement of others to use it in their watches.

Unfortunately, over the longer term, the Karrusel was doomed to become a footnote to its older brother, the tourbillon. This is due to a range of factors. Forsey believes that the Karussel didn't take off because it hadn't been developed sufficiently by the time the wristwatch came along. It wasn't ready to be miniaturised, whereas the tourbillon was. Nowadays, the most well-known brand to use the Karrusel is Blancpain, while tourbillon watches are included in the catalogues of brands from Tag Heuer to Audemars Piguet and Patek Philippe. It seems Breguet won the race.

Pushing the Tourbillon forwards

 

The British connection to this story doesn’t stop with the Karrusel. The flying tourbillon was invented by a British watchmaker named Robert Benson North, who was granted the patent for it in 1904. You can actually still find a copy of this patent online.

In it, North states that his invention has the same aim as Breguet’s tourbillon, but that he also hopes “to attain a cheap and practical form or mode of mounting the revolving platform which carries the escapement.” This patent actually contradicts what many believe to be the origins of the flying tourbillon, as it has long been linked to Professor Alfred Helwig, who was working out of the Glashütte School of Watchmaking in 1920.

 

A patent filed by Robert Benson North for his early version of a flying tourbillon

The drawings submitted by North that were attached to his patent. 

 

The basic principle is identical to the standard tourbillon. The main distinguishing factor is that a flying tourbillon has no upper bridge for the cage; it is supported only from below. The distinction is evident when looking at a flying tourbillon, because the upper bridge which connects the top of the pinion to the main plate is missing.

As a result, the bearing on which the tourbillon is rotating is below the cage, with the spinning platform balanced on top of that bearing. It still has the fixed gear that Forsey mentioned earlier, with a planetary gear working its way around it, but with no bridge or bearing above holding it in place.

This is why North’s invention, while not named a flying tourbillon, fit all the criteria, while being 16 years earlier than the German. Whether Helwig knew of North’s invention at the time of his work, we’ll never know, but we can be certain that both knew of, and probably worked on, tourbillons before they released their own creations.

 

Two tourbillon movements made by Derek Pratt, one normal and one flying

A regular and flying tourbillon, both made by the great watchmaker Derek Pratt. 

 

Despite the flying tourbillon being invented later than the Karrusel, it appears to have had more success in the modern era of wristwatches. Its influence has been long-lasting, to be found in the work of some of the greatest contemporary watchmakers. Derek Pratt, the skilled hands behind the resuscitation of Urban Jürgensen, is one such example.

Among other creations, he is probably most famous for the three oval pocket watches with flying tourbillon, remontoir, détente escapement, power reserve and Réaumur scale, which he completed between 1987 and 1992. Every single one required 4,000 hours of work. That’s over 166 days of continuous work, excluding any time for sleep.

 

Derek Pratt, George Daniels and the Audemars Piguet Sales Director for the UK

George Daniels, the Sales Director in the UK for Audemars Piguet and Derek Pratt, stood in front of one of Daniel's classic racing cars. Courtesy of Philip Wilson Publishers.

 

Whereas more contemporary interpretations of the flying tourbillon have been taken by the likes of Richard Mille and Audemars Piguet, Pratt’s approach is clearly steeped in tradition. It is an homage to some of the important watchmakers we’ve had the chance to discuss, notably Abraham-Louis Breguet, John Arnold and Alfred Helwig.

It will come as no surprise, on account of his skill and respect for tradition, that Derek Pratt was a close friend of George Daniels for many years. He was also actively involved with Daniels in his efforts to get the Swiss industry to adopt the co-axial escapement.

 

Tourbillon pocket watch made by Derek Pratt

Getting up close and personal with a tourbillon made by Derek Pratt.

 

In Pratt’s extensive obituary, written by George Daniels himself in the Horological Journal, Daniels made sure to point out the following, “His pocket tourbillon chronometers are exquisitely made and finished and are now in the hands of some of the most knowledgeable horologists to be found in Europe. His work was almost always made by hand methods because he enjoyed the feel of the tools and the freedom of introducing alterations as he worked. His workshop was innocent of CAD and repetitive tooling. Serious horologists were always welcome to see and discuss his methods.”

Indeed, nowadays, with the advent of modern technology and computer-aided design, creating a tourbillon has become that bit more accessible. That is partially why, at the beginning of the early 21st century, many brands were able to incorporate a tourbillon model into their collection. The greater ease of production, coupled with the perception of craftmanship and exclusivity associated with the complication, resulted in great commercial success for the tourbillon during that period. Though many were produced, it is worth pointing-out that few were made according to the more traditional, painstaking methods introduced by Breguet and followed by others. Let’s look a bit more closely at how the complication has evolved in more modern times.

The Tourbillon in Modern Times

 

Nowadays, the complication has become far more popular than Breguet could ever have imagined when he invented it over 200 years ago. While Forsey affirms that, “yes, you can machine-make a tourbillon these days”, crafting the complication according to more traditional, exacting methods remains challenging.

Touching upon the work of George Daniels is crucial. Daniels was one of the few watchmakers who built complete watches by hand, from his workshop on the Isle of Man, at a rate of around one watch per year. His truly hand-crafted pieces have set the standard for contemporary independent watchmaking. During his life, and even more so recently, they have proven that the interest in fine, artisanal tourbillons is still very much alive.

 

Macro shot of the movement of a tourbillon pocket watch made by George Daniels

The fine craftsmanship of a George Daniels pocket watch.

 

At the time when he was working, assembling watches by hand, especially ones housing such obscure complications, was nothing short of contrarian. As Barter points out,

“Daniels was working at a time in the industry when the quartz crisis had really taken hold. Many big companies were more interested in how to make the best electronically powered movement, rather than investing in high end, technical complications.”

Of course, he integrated his famed co-axial escapement into his pocket watches, as well as the small handful of wristwatches, he made housing a tourbillon. Initially catering to a select demographic of passionate horological collectors, the appreciation and understanding of Daniels’ work has expanded over the years.

 

Design drawing for George Daniels Blue wristwatch
Design drawing for George Daniels Blue wristwatch

The technical drawings of George Daniels' unique Blue watch, featuring a tourbillon.

 

It has inspired multiple independent watchmakers to follow down his path, adding an additional reference point to their list of inspirations. One such watchmaker is François-Paul Journe, who cites George Daniels alongside Abraham-Louis Breguet as one of his most significant influences. 

Journe famously decided that his first ever watch should be a tourbillon, modelled on the work of those he admired. When contemplating how to establish his own brand in 1999, he equally decided that his first production wristwatch should be a tourbillon with a remontoire. Whereas some close to him have said that Journe initially wanted to produce a time-only watch as his first model, he realised the need to prove his skill as a watchmaker. The tourbillon seemed like the obvious choice.

It’s rather interesting to think that, over time, the aura which surrounds the tourbillon has grown to such an extent that it is now seen as a rite of passage for any watchmaker aspiring to greatness. Its visual appeal, the great watchmakers who have worked on it and the skill needed to assemble one according to more traditional methods, have all contributed to this.

 

The unique design of the tourbillon cage that helped launch F.P. Journe's career.

 

The desire to tackle this complication held by young, ambitious watchmakers is obvious when examining the work of Rémy Cools, who only recently announced his first ever production watch as an independent. Following in the steps of those he admires, Cools has decided that his first model would be a Souscription Tourbillon. The souscription, or subscription, model is borrowed from Breguet, and Journe after him. The basic idea is to encourage collectors to purchase a watch by placing a deposit up front in order to finance its completion, in exchange for a discount on its future price. “It requires enormous precision and concentration to manufacture a tourbillon”, Cools tells us, “personally I think it is one of the most beautiful complications.”

 

Remy Cools tourbillon souscription on his wrist
The tourbillon of Remy Cools Tourbillon Souscription

The work of young watchmaker Rémy Cools.

 

Cools, who started watchmaking at the age of 11, worked with Greubel Forsey on their latest Hand Made 1 model, having only recently setup his own workshop. Citing Breguet, Daniels and Journe as his inspirations, you can clearly see the design language of these three craftsmen throughout his work.

The timepieces which Cools is now creating are traditional in their design, using a modified Swiss anchor escapement inside his 60 second tourbillon. Compare these to the work of his former employer, Greubel Forsey, and the difference is stark. Whereas Greubel Forsey certainly understand and master traditional techniques, they aim for technical innovation and to push the boundaries of watchmaking. Indeed, the brand is known for being the innovators of the double tourbillon 30°, as well as the famed quadruple tourbillon.

“Because of the 30° angle, we could have a larger balance wheel than we would have if the tourbillon was placed at 90°”, Forsey explains. “This resulted in our double tourbillon maintaining a rate of 0.3 and 0.8 seconds a day during the Concours International de Chronométrie test.” This was in 2011, where Greubel Forsey took home the top prize of that year’s competition, with an impressive final score of 915 points. In essence, despite their contemporary aesthetic, it could be argued that Greubel Forsey are much more loyal to the original purpose of the tourbillon than many others. After all, they are building on its original purpose, namely improving timekeeping through innovation.

 

Greubel Forsey sketch of their Art Piece Edition Historique

A sketch of the Greubel Forsey Art Piece Edition Historique with their double tourbillon 30°.

 

Of course, independents aren’t the only ones tackling the tourbillon. In fact, much of the popularity which has built-up around the complication in the last few decades was born-out of the efforts of more established brands. For example, in 2016, Tag Heuer announced the Carrera Heuer-02T which was the cheapest Swiss made tourbillon on the market at the time, at CHF 15,000.

This model was released shortly after Jean-Claude Biver took over control of the brand, refocusing it on the more accessible end of the market. Whilst it could not be more different in nature than the work of others we’ve discussed, the impact of these more commercially minded pieces should not be ignored, as they contribute to the expanding allure which surrounds the complication. It also poses a key question to the rest of the industry, namely, why do tourbillons have to be so expensive? In some cases, the answer is clear. In others, less so.

On the other end of the spectrum is the new style of tourbillon which Jaeger-LeCoultre introduced in 2004, the multi-axis, gyrotourbillon. This is a watch that was born of the computer age, as the design was only made possible with the advent and advancement of CAD design. Now that the potential of this technology has gone even further, this movement has seen its fifth generation released at SIHH last year. Despite adding a Westminster chime and a calendar the movement, it is now smaller and thinner than ever before.

 

Greubel Forsey hand Made one setting of the tourbillon by hand

The mounting of the tourbillon into the Greubel Forsey Hand Made 1.

 

This idea of a multi-axis and multi-cage tourbillon was then taken to another level by the independent watchmaker, Vianney Halter, with his Deep Space tourbillon. Within the dramatically domed sapphire, the escapement sits inside the tourbillon cage which rotates on its first axis once a minute — so far, so normal. This is then sat inside another cage which is rotating on an axis perpendicular to the first, once every six minutes. This whole construction is then mounted on a cradle, that is being turned around a set of gear teeth, which hugs the inside of the minute track that travels around once every 30 minutes. A mesmerising and complex contraption, one wonders what Breguet would have thought if he saw the creative ways in which people have approached his invention today.

 

Vianney Halter Deep Space tourbillon watch with its domed sapphire crystal

The Deep Space tourbillon from Vianney Halter could be floating in zero gravity. 

 

The tourbillon is, and will likely remain, one of the most popular and captivating complications out there. With the likes of the independents pushing the boundaries of creativity and what is mechanically possible, while the big brands continue to bring the tourbillon to new audiences around the globe, it doesn’t look set to stop. Appearing in a whole range of different configurations in the last 200 years, it’s anyone’s guess what the tourbillon might look like another two centuries from now.

Our thanks to Stephen Forsey, Alex Barter, Rémy Cools, Sotheby's and Breguet for generously offering their time and providing the images to help illustrate this article. We would also like thank the AHSOC for providing archival observatory trail records. 



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