Walt Odets review Chronoswiss Delphis

You can learn many things on Instagram if you follow the right people.

I learned about Walt Odets, and his extraordinary review of the Chronoswiss Delphis, from @crazywatches.pl.

The name meant nothing to me. Apparently, that simply means I arrived rather late to the right corner of the watch world.

Walt Odets was one of the most important watch writers of the early internet era, although watchmaking was neither his profession nor the work for which he was best known outside our small world. He was an American clinical psychologist and author who spent much of his professional life writing about the experiences of gay men and the psychological effects of the AIDS epidemic. He was also a pilot, a photographer and a very serious amateur watchmaker.

Odets was born in 1947, the son of playwright and screenwriter Clifford Odets, and died in July 2026 at the age of 79.

For watch collectors, his legacy is a body of writing called The Horologium, published through TimeZone. Odets did something that still feels unusually honest today: he bought watches, took them apart, photographed what he found under magnification and judged the work in front of him, not the name on the dial or the story in the press release.

He examined movements from Patek Philippe, Vacheron Constantin, Audemars Piguet, A. Lange & Söhne, IWC, Omega, Rolex and others. He looked at construction, finishing, lubrication, adjustment and performance. Decorative finishing did not automatically impress him, and a famous name did not receive special protection.

His best-known article is probably his examination of the Rolex Explorer 14270. He found a robust and accurate watch, but also internal work that he considered disappointing at its price. More than twenty years later, people are still arguing about it. That tells us something about both the influence of the article and the difficulty of separating an object from the mythology surrounding its brand.

Odets was not writing the usual watch “reviews.” He was investigating the watch as a machine.

And that brings us to the subject that concerns us: jumping hours.

The Chronoswiss Delphis

In September 2002, Odets published The Chronoswiss Delphis, a detailed examination of one of the most distinctive jumping-hour watches of its period.

The correct model name is Delphis, with an “s,” although it is often shortened accidentally to Delphi.

The original Delphis combined three completely different ways of displaying time:

The hour appeared digitally through an aperture and jumped instantaneously.

The minutes were indicated by a retrograde hand travelling across an arc.

The seconds were displayed conventionally on a small subdial at six o’clock.

That mixture was part of what attracted Odets to it. He called the Delphis arguably Chronoswiss’s most interesting and original watch, and noted that its three indications each communicated time in a different way.

The Delphis combines a jumping-hour aperture with retrograde minutes. Photograph by Walt Odets, originally published in The Horologium.

The conventional small-seconds display at six o’clock provides the third method of showing time. The oval cartouche carries the individual watch number.

The watch was also very recognisably Chronoswiss. It had the guilloché dial, onion crown and coin-edged case associated with the company under its founder, Gerd-Rüdiger Lang. But the real interest was hidden under the dial.

From Enicar to Chronoswiss

The Delphis used the Chronoswiss calibre C.124. Underneath the complication, its foundation was the automatic Chronoswiss C.122, which derived from the Enicar calibre 165 introduced in 1967.

Chronoswiss did considerably more than place its name on an old Enicar movement. Odets found better upper-plate finishing and several technical alterations. One clear example was the conversion of Enicar’s original bidirectional automatic winding system to unidirectional winding.

The visible movement, therefore, was attractive and carefully presented. The complication underneath the dial was a different matter: less beautifully finished, but much more interesting mechanically.

The large 24-hour ring

One of Odets’s photographs shows the complete hour ring surrounding the mechanism. It is the image that first caught my attention.

The ring is numbered from 1 to 23, with the Chronoswiss logo occupying the midnight position. In other words, this was a true 24-hour jumping display rather than a 12-hour disc repeating the same cycle twice per day.

The complete 24-hour ring fitted above the movement. The Chronoswiss emblem occupies the position corresponding to midnight.

It is also a useful reminder that the numeral seen through a small window may belong to a surprisingly large component. On the wrist, the owner sees only a single hour. Underneath the dial, an entire numbered ring surrounds the movement.

With the central cover and hour ring removed, the jumping-hour and retrograde mechanism becomes visible. Odets identified the principal components directly on the photograph. For someone thinking about the architecture of a jumping-hour watch, these photographs are more instructive than many polished movement renders. They show the real relationship between the movement, the complication and the display.

A very clever mechanism

What impressed Odets was the simplicity of the system. The jumping hour and retrograde minute display were not two unrelated complications stacked on top of one another. They were coordinated parts of the same mechanism.

The central mechanism: snail cam (1), minute-hand pinion (2), jumping-hour lever and rack (3 and 3B), spring lever (4) and retrograde spring (5).

A snail cam is driven continuously by the movement. Its outer edge acts against a plate attached to the jumping-hour lever. As the cam turns, a rack on that lever rotates the minute-hand pinion. The pinion moves the minute hand progressively across its scale while also acting on another rack that compresses the retrograde spring.

For most of the hour, everything happens slowly. The minute hand advances, the spring stores energy and the pawl connected to the hour lever slides across the teeth or notches beneath the hour ring.

During normal running, the minute-hand pinion turns clockwise while the retrograde spring is progressively compressed.

At the end of the hour, the trailing edge of the snail cam releases the lever.

The stored energy is released immediately. The minute-hand pinion rotates backwards and returns the minute hand to zero. At the same moment, the hour lever moves in the opposite direction and its pawl pushes the hour ring forward by one position. A separate jumper spring indexes the ring and holds the new hour correctly in the aperture.

One release creates both events: the retrograde return of the minutes and the instantaneous jump of the hour.

The release phase: the spring decompresses, the minute pinion reverses, the minute hand returns to zero and the hour ring advances.

It is a simple and intelligent solution. It is also an excellent example of why “simple” in watchmaking does not necessarily mean easy.

Where Odets found the weakness

This is where the article becomes more than an explanation of a clever mechanism.

Odets discovered that the hour change in the watch he examined was occasionally unreliable. The correct operation of the advancing pawl depended on a very precise adjustment of a small spring. He eventually reshaped the tip of the pawl and carefully adjusted the spring before the hour ring advanced dependably. Ain't this something we all suffer from with our jumping hour watches?

The hour-advancing pawl (6) and its tensioning spring (7). Odets found that reliable advancement depended on the precise adjustment of this small spring and the shape of the pawl tip.

That is a significant observation.

The Delphis did not fail because the basic idea was foolish or excessively complicated. On the contrary, Odets considered the design remarkably simple and clever. The weakness was concentrated in the relationship between a pawl, its spring and the teeth beneath the hour ring. A very small component and a very small adjustment determined whether the principal complication worked every time.

He also criticised the minimal finishing of the hidden complication plate and its operating parts. This was not primarily an aesthetic complaint. Odets distinguished between decorative finishing and functional finishing, and he would have preferred more attention in the mechanism itself, not merely on the parts visible through the caseback.

His photographs also documented substantial molybdenum grease on the high-load surface of the snail cam. This is particularly relevant today because, according to the watchmaker whose post led me to Odets, Chronoswiss did not issue a detailed service bulletin explaining exactly where and how the mechanism should be lubricated. A good technical teardown may therefore preserve practical knowledge that the manufacturer did not make easily available.

Odets’s verdict

Odets’s final assessment was balanced.

He admired the 38 mm case, the dial, the originality of the display and the value the watch offered compared with other mechanical complications. At the time, he believed the Delphis had no real competitor offering this kind of mechanism at anything close to its price.

But he did not confuse originality with perfection. He wanted better functional finishing beneath the dial and a more reliable method of controlling the tension on the jumping-hour pawl.

He described the Delphis as “a decent execution of a novel idea that speaks to many horological traditions.” That is not the exaggerated language normally associated with a watch review, but it is meaningful praise coming from him.

Why this old article still matters

The review was published in 2002, but it feels especially relevant now.

Today we are surrounded by excellent watch photography and beautifully produced launch material. What remains rare is an independent writer purchasing or obtaining a watch, dismantling it completely, understanding how it works and showing both the clever solution and the weak point.

For those of us interested in jumping hours, the article also contains a valuable lesson. The drama occurs once every sixty minutes, but reliability is created through thousands of small, repetitive interactions between the cam, lever, spring, pawl, jumper and hour ring.

A prototype that jumps correctly a few times is not necessarily a successful mechanism. It must continue to jump correctly as lubrication migrates, tolerances accumulate, the mainspring delivers different levels of torque and the components begin to wear.

That may be the most important thing I learned from Walt Odets: the interesting question is not only whether a mechanism works, but how it works, where it is vulnerable and whether the execution is worthy of the idea.

I came across his name by chance, through an Instagram post about servicing an old Chronoswiss. I ended up discovering one of the most important technical watch writers of the internet era, and one of the best examinations ever written about a jumping-hour mechanism.

Not bad for a morning on Instagram.

Sources and further reading

Walt Odets, The Chronoswiss Delphis, TimeZone, 16 September 2002.

The Walt Odets Archive, a curated guide to Odets’s technical watch writing.

Jack Forster, Walt Odets Made Me Do It, a personal account of Odets’s influence on watch journalism.

Walt Odets on His Five Favorite Watches, Beyond the Dial, 8 November 2022.

Walt Odets, official website and information about his work as a psychologist and author.

@crazywatches.pl, whose post led me to the Delphis article.

I collect jumping-hour watches for a very simple reason: I like seeing the hour jump. That sounds obvious. But spend enough time looking at jumping-hour watches and you begin to notice a surprisingly common design problem.

The hour is displayed through an aperture, often at 12 o'clock. The minutes are displayed with a conventional central hand. And precisely when the interesting thing is supposed to happen, when the minute hand reaches 60 and the hour changes instantaneously, where is that hand? Directly over the jumping-hour window.

You've designed an entire mechanical complication around something that happens once every sixty minutes. I've waited an hour to watch it happen. And then you've put a hand in front of it. Why? The jump is the show!

A jumping hour replaces the conventional hour hand with a numeral, usually carried on a rotating disc. At the change of the hour, instead of progressing gradually, the indication jumps instantaneously to the next numeral. If all I wanted was an efficient way to know the time, conventional hands would do the job perfectly well.

Part of the attraction of a jumping hour is the mechanical event itself. At 10:59:59 there is a 10 in the window. A second later, it is gone and 11 has taken its place. That's the moment I want to see.

There are hundreds of mechanical digital watches that avoid this issue completely by displaying both hours and minutes on discs. They aren't relevant to this discussion because there is no conflict to solve. The interesting design problem begins when you decide that you want both a jumping-hour aperture and a minute hand. What do you do with that hand when it reaches 60?

Some very important watchmakers seem to have decided that covering the aperture was perfectly acceptable. I disagree.

Audemars Piguet: Really?

In 2009, Audemars Piguet introduced the Jules Audemars Répétition Minutes Heure Sautante, combining a jumping-hour indication with the vastly more complicated minute repeater. This was serious haute horlogerie with an enormous price attached to it. Yet look at the basic time display.

The jumping-hour aperture is at 12. The minutes are indicated by a conventional central hand. At exactly the moment the hour jumps, the minute hand reaches 12 and passes directly over it. Obviously, the extraordinary price of this watch reflected the minute repeater, movement construction, finishing and extremely limited production rather than merely the jumping-hour mechanism. Still, it's difficult to resist the question.

You can make a minute repeater. You can make a jumping hour. You can make a watch costing close to half a million dollars. But you couldn't find a way for me to see the hour jump unobstructed? Really, AP?

Patek Philippe did it twice

Patek Philippe provides an even more interesting example because essentially the same arrangement appeared generations apart. In 1927, Patek Philippe produced an important jumping-hour wristwatch with a tonneau-shaped case, an hour aperture at 12 and conventional central minutes. Then, in 1989, for the company's 150th anniversary, Patek returned to the design with Reference 3969. The 3969 deliberately echoed the earlier watch. Only 500 were produced, 450 in pink gold and 50 in platinum, powered by Patek Philippe's manually wound Calibre 215 HG. The hour aperture is at 12 and a traditional minute hand sweeps around the dial. Consequently, at precisely the moment the numeral changes, the minute hand arrives in front of it. In this case there is an obvious explanation: the 3969 was conceived as a historical tribute, and the layout was part of what Patek was recreating.

Historical fidelity explains the decision. It doesn't make me like it any more.

Breguet: A Solution That Goes Back Much Further

Breguet provides an interesting historical answer to the problem because the basic idea appears much earlier than the modern wristwatch examples in this article. Look closely at this vintage Breguet jumping-hour pocket watch. The jumping-hour aperture sits at 12, but the minute scale doesn't extend all the way out to it. Instead, the minutes occupy a smaller circle inside the dial, and the minute hand is correspondingly shorter. When the hand reaches 60, it points toward the jumping hour but stops well below it. The two indications have effectively been given separate territories.

Decades later, Breguet used essentially the same principle on the Ref. 3420 Heures Sautantes. Again, the jumping-hour aperture sits above the minute scale. Again, the minute track occupies a smaller radius. And again, the central minute hand is deliberately short enough that when it reaches 60 it never crosses the hour window. There is nothing complicated about the solution. Breguet simply designed the minute display around the jumping hour rather than placing one on top of the other. And remarkably, the earlier pocket watch shows that this wasn't a new idea.

Rolex: The Same Principle, Taken Further

The vintage Rolex Prince Jumping Hour approaches the problem in a similar way, but separates the indications even more clearly. The jumping hour has its own aperture at the top of the dial, while the minutes are moved onto a dedicated subdial below. The implementation is different from Breguet, but the principle is much the same: Give the jumping hour its own space.

Breguet achieves that by reducing the radius of the minute display and shortening the hand. Rolex achieves it by moving the minute indication into a separate register. Neither requires transparency, an opening in the hand or any other trick to reveal the jump. The minute hand simply never gets there.

Doxa also knew what to do

(Photo taken from SwissWatches Magazine)

Collector’s Choice: @jumphourking Ruud van Rijn Talks Jump Hour Watches

Some oe watchmakers recognized the problem

This is where the subject becomes more interesting. Other manufacturers clearly noticed that the minute hand and jumping-hour aperture were competing for the same piece of dial at exactly the wrong moment.

They tried to solve it, not always in ways that completely convince me.

Christopher Ward: transparent isn't invisible

Christopher Ward addressed the obstruction by using transparency in the minute hand. The reasoning is easy to understand. When the minute hand reaches the jumping-hour aperture, the numeral isn't simply hidden behind an opaque piece of metal. You can still see what is happening underneath. It is certainly an improvement.

For me, however, it doesn't completely solve the problem. I've waited sixty minutes for the jump and I'm still viewing it through another component, with the edges and reflections of the hand sitting between my eye and the hour disc. This is obviously a matter of preference. Someone else may consider the problem solved. I don't. Transparent isn't the same as invisible.

MEC-1 takes transparency further

The MEC Watches MEC-1 takes the same basic approach considerably further. Rather than simply opening part of the minute hand, MEC uses a centrally mounted sapphire minute hand. Transparency is also part of the wider architecture of the watch. The MEC-1 uses a smoked sapphire dial that exposes much of the mechanism beneath it.

The watch itself is technically interesting: a manually wound manufacture movement, instantaneous jumping hour and production limited to 50 numbered pieces. It's a coherent solution, and certainly more sophisticated than simply putting an opaque hand over the aperture. But my preference remains the same.

If the jumping hour is the feature I'm waiting to see, I'd rather have nothing between the aperture and my eye when it happens.

Omega turned the problem into the solution

Omega approached the same problem very differently. And this is one of the solutions I like most. Omega kept the conventional central minute hand. The jumping-hour aperture remained at 12. In other words, the geometry that causes the problem was still there. But look at the end of the minute hand. Instead of a solid pointer, there is a large circular opening. As the minute hand reaches 60, that opening arrives at the jumping-hour aperture. Rather than covering the numeral, the hand surrounds it. The minute hand becomes a moving window frame. I find this much more satisfying than making the hand transparent. Omega doesn't try to pretend that the minute hand isn't there. Its arrival at 12 becomes part of the presentation. The circular opening draws your eye directly toward the aperture at the moment the hour changes. The component that would normally cause the problem becomes part of the solution.

Cartier replaced the hand with a disc

The Rotonde de Cartier Jumping Hour takes another approach that deserves inclusion because, unlike conventional digital-minute watches, it still gives us a moving analogue-style indication of the minutes. But it does so without a conventional hand.

Instead, Cartier uses a rotating minute disc beneath a fixed reading point. The minutes still progress continuously around the dial, but there is no physical hand extending from the center and sweeping across the jumping-hour aperture. This distinction is important. Cartier hasn't simply replaced the minutes with another digital window. It has retained the visual idea of minutes travelling around a dial while eliminating the component that causes the obstruction. The jumping hour remains isolated. I would drop the Roman Numerals if I were you though...

Sartory-Billard made the hand disappear

The modern Sartory-Billard SB10 offers another interpretation. Here the indications are carried by ultra-thin sapphire discs rather than conventional hands. One carries the jumping hour, while another rotates continuously to indicate the minutes. The minute indication therefore retains movement around the dial without placing an opaque hand over the hour aperture. Sartory-Billard also enlarged the jumping-hour aperture to improve the visibility of the numeral and its transition. That's a detail I appreciate because it suggests that seeing the jump wasn't treated merely as a consequence of the mechanism. It was considered part of the experience.

My preferred solution: retrograde minutes

There are clearly many ways to deal with this problem. Move the indications apart | Put an opening in the minute hand. | Make the hand transparent. | Replace it with a disc. | Use sapphire. But if I were choosing the solution, I'd take a different approach.

Retrograde minutes.

Not simply because a retrograde minute hand can avoid the jumping-hour aperture. Because it gives me something else to watch. A retrograde minute hand progresses along an arc from zero to sixty. When it reaches the end, it doesn't continue around the dial. It snaps back to zero. Now synchronize that with a jumping hour. At 10:59:59, both mechanisms are waiting. The hour disc jumps from 10 to 11. At virtually the same moment, the minute hand flies from 60 back to zero. Two jumps. At once. Instead of treating the minute hand as something that needs to be kept away from the jumping hour, you've turned it into part of the event.

Gérald Genta made it a signature

Gérald Genta repeatedly combined jumping hours with retrograde minutes, and the arrangement became one of the recognizable features of watches produced under his own name.

The hour gets a dedicated aperture. The minute hand travels across a large arc. At the end of the hour, the two indications act together.

The Retro Classic used the arrangement in a relatively restrained form. The Retro Sport (as seen in the image) applied the same principle in a much more contemporary case.

There were also the well-known Disney character watches, where a character's arm serves as the retrograde minute hand.

While these aren't personally among my favorite Genta designs (sorry not sorry, Disney) they demonstrate just how central the retrograde mechanism was to his approach.

In those watches the movement of the minute indication becomes very literal: the character's arm progresses across the scale and returns at the change of the hour. Whether the dial is restrained or playful, the underlying idea is the same. The minute indication doesn't interfere with the jumping hour. It participates in the event.

Vacheron Constantin made the same choice

Unlike the two other brands of the Holy Trinity the Vacheron Constantin Saltarello Ref. 43041, introduced in 1997, is another particularly good example. The jumping hour occupies an aperture at 12. Below it, the retrograde minute scale forms a broad arc across the upper half of the dial. The minute hand travels progressively from zero to sixty.

At the top of the hour, the numeral changes and the minute hand returns to zero. The Saltarello was produced in a total of 500 examples across white, pink and yellow gold and used Vacheron Constantin's ultra-thin automatic Calibre 1120/2 with the additional jumping-hour and retrograde mechanism. What matters to this discussion, though, is the display architecture.

Vacheron didn't have to find a way for the minute hand to pass over the jumping-hour aperture without obscuring it. The minute hand never needs to go there. And the return of the retrograde hand gives the wearer a second instantaneous event to watch at precisely the same moment as the jumping hour. For me, that's preferable to merely solving the obstruction. It adds something.

You don't need to be Holy (or Gerald Genta)

This same principle appears at a very different price level. Xeric has experimented with several unconventional approaches to jumping-hour displays and, importantly, seems consistently aware that the jumping indication should remain visible. Their designs are modern, fun and original (usually), but their watch I took as an example, is the Retroscope, their Quartz affordable wrist watch.

Its Retroscope combines jumping hours with retrograde minutes. The minute hand travels toward the end of its scale. At the change of the hour, it returns to zero while the hour indication advances. The execution and movement are obviously in a completely different category from Vacheron Constantin or Gérald Genta, but the basic design principle is the same.

And that illustrates something important about this entire subject. This isn't fundamentally a question of price. It's a question of thinking about what the wearer is supposed to experience.

So is covering the jump actually bad design?

I guess I'm being a little provocative. Putting a minute hand over a jumping-hour aperture doesn't make a watch badly made. It doesn't make the Patek Philippe 3969 historically unimportant, and it certainly doesn't diminish the technical achievement of an Audemars Piguet minute repeater.

Someone else may own any of those watches and never be bothered by this issue. I am. Because I don't collect jumping-hour watches merely because they're an unusual way of displaying time. I enjoy what happens at the change of the hour.

And once you look at the complication that way, the minute indication creates a surprisingly interesting design question: How do you display the minutes without spoiling the best moment of a jumping-hour watch? Some manufacturers accepted the obstruction.

Christopher Ward and MEC used transparency.

Omega turned the minute hand into a window.

Rolex separated the indications.

Cartier replaced the conventional hand with a rotating disc.

Sartory-Billard used transparent discs.

And Gérald Genta, Vacheron Constantin and others took the approach I prefer. They didn't try to hide the minute hand, they gave it something else to do. Make it jump too.

Because if I've waited sixty minutes for the show, I want a good view.

That's what I am talking about

A beautiful watch by Corum, but I can't see it jump

In 2018, IWC celebrated its 150th anniversary with an unusual watch: the Tribute to Pallweber Edition “150 Years”. At first glance, it looks almost modern. Instead of conventional hour and minute hands, the time appears through windows: one number for the hour and two for the minutes.

That first glance must have been very different 130 years ago when Josef Pallweber, a watchmaker working in Salzburg, presented his invention: a mechanism for a watch that is completely digital - it shows the hour and the minute in numbers, instead of on a dial. The system used three rotating discs: one for the hours, one for the tens of minutes and another for the individual minutes. Pallweber's American patent describes this arrangement, with the minute disc advancing once every minute, the tens disc every ten minutes and the hour disc once an hour. The first watchmaker to adopt this revolutionary mechanism was IWC that began making watches based on Pallweber's system in 1884.

Around 20,000 were eventually made in Schaffhausen before production ended in 1890. However, convincing numbers to jump brings about quite a mechanical challenge. A normal watch movement turns its wheels continuously. A digital display needs the numbers to remain still and then suddenly move to the next position.

An article by Joseph Flores in Horlogerie Ancienne examines several surviving jumping-display pocket watches from roughly this period and shows that watchmakers found different solutions to the same problem. One uses a small spring that is armed and released at regular intervals. Another relies on interrupted gearing. The most interesting example has a 50-tooth wheel that initially seems incompatible with the required gear ratio. Looking closer reveals the trick. Some of the teeth are effectively bypassed and one leaf of the driving pinion is deliberately cut away. At a specific point in its rotation, this unusual geometry allows the display wheel to advance suddenly. Something that might look like damage is actually part of the mechanism. This also illustrates one of the difficulties with these early watches.

Moving relatively large discs instantaneously requires energy. IWC acknowledges that the original Pallweber watches suffered from a relatively limited power reserve because of the energy needed to advance their displays. More than a century later, IWC approached the same problem differently. The 2018 Tribute uses the hand-wound calibre 94200. Instead of simply reproducing the old mechanism, IWC gave the jumping display a separate wheel train and its own barrel. Every 60 seconds the mechanism releases it briefly to advance the single-minute disc. Every ten minutes the tens disc advances, and once an hour the hour display jumps. The main timekeeping train therefore doesn't have to provide the sudden bursts of energy required by the display.

That is what I find most interesting about the Pallweber rebirth story. The 2018 IWC is not a retro watch. It connects beautifully with a legacy of a mechanical challenge that watchmakers have been struggling with since the 1880s and solves it, without sacrificing the tradition and history it is built on.

One of the things I find interesting about collecting 1970s jumping hours is how often familiar movements, designs and even complete watches appear under completely different names.

But there is an important distinction to make. Using the same movement doesn't make two watches the same.

I have three good examples in my own collection. My Tressa Spaceman jumping hours, my Tressa Saltomatic and a Tenor-Dorly are all powered by the A. Schild AS 2072. I have opened the Tenor-Dorly myself, so there is no mystery about the movement inside it.

Yet nobody would mistake these three for the same watch. Their cases, dials and displays are completely different. They simply share the same mechanical base.

Then it gets more interesting.

The Tressa Saltomatic has several close relatives carrying other brand names that look remarkably similar. This wasn't unusual in the Swiss watch industry of the period. Movement manufacturers supplied ébauches, while cases, dials and other components could come from specialist suppliers. The company whose name appeared on the dial was not necessarily responsible for everything underneath it.

The Spaceman takes this idea further.

André Le Marquand designed the original Spaceman for Catena, and versions of the design subsequently appeared under numerous names, including Tressa Lux, Fortis, Zeno, Jules Jurgensen, Octo, Omax, Vialux and Harlem. These weren't simply unrelated watches that happened to use the same movement. They belonged to the same recognizable design family.

The jumping-hour version is much less common than the broader Spaceman family. My Tressa jumping-hour examples use the AS 2072, although I haven't found reliable documentation proving that every jumping-hour Spaceman used that caliber, so I prefer not to make that claim.

There is another good example in my collection.

I own four Mondia automatic jumping-hour chronographs powered by the TDBK 1376. The initials refer to the companies involved in its development: Tenor-Dorly, Dubois-Dépraz, Brac and Kelek. The result combined an automatic movement, mechanical digital time display and chronograph.

Again, Mondia wasn't alone. The same TDBK 1376 appears in watches carrying other names, with examples known under Waltham, Tenor-Dorly, Kelek, Sandoz, Elgin and Precimax, among others.

This is where collecting obscure Swiss watches becomes a little like detective work.

Two watches can look completely different but share the same movement. Two others can look almost identical while carrying different names. And sometimes essentially the same watch was offered by a whole collection of brands.

So when I find an unfamiliar name on a 1970s jumping hour, I don't dismiss it.

I start looking for its brothers.

Sources

Fratello Watches André Le Marquand's Timeless Spaceman Audacieuse

Peter Doensen Watch: History of the Modern Wrist Watch

The Watch Spot Nivada Chronograph, TDBK Cal. 1369 Technical history of the TDBK 1369 and 1376 family

Hodinkee They Made Some Pretty Terrible Watches In The Good Old Days Too

Watchismo 1974 Waltham Jump Hour Chronograph

Sometimes you buy a watch knowing exactly what it is. And sometimes you buy one because you like it, and only afterwards discover what you actually bought.

This Gianni Bulgari Enigma belongs firmly in the second category.

I don't usually buy quartz watches. There is nothing wrong with quartz, of course, but as a collector I am naturally more attracted to mechanical movements. This one was different. I loved the design from the moment I saw it: the strange horseshoe-shaped dial, the single minute hand, the jumping-hour window at six and the beautifully integrated bracelet. It looked unlike almost anything else in my collection.

Then I started researching it.

The Gianni Bulgari Story

Gianni Bulgari was a member of the third generation of the Bulgari family and served as chairman and CEO of the family company before leaving during the 1980s. He subsequently established his own business in Switzerland, eventually producing watches under the GB Enigma name.

That alone makes these watches interesting to me. They come from someone intimately connected with one of the great names in Italian jewellery, but working independently and putting his own name and ideas behind the watches.

There is also an interesting historical coincidence. Bulgari would later acquire the Gérald Genta and Daniel Roth brands in 2000, bringing some very serious complicated watchmaking into the Bulgari universe. By then, Gianni had long since gone his own way.

And among his independent creations was a jumping hour.

Finding the Dahl

Identifying my particular watch took some work.

Eventually I found a 1993 Europa Star report showing two Gianni Bulgari designs: the Timeo and, unmistakably, my watch, identified as the “Dahl.”

The contemporary description calls the Dahl a jumping-hour “BITIME” and says that its complex mechanical feature is “piloted by an ETA module.” The wording is rather confusing, especially because the watch is unquestionably quartz.

Fortunately, another piece of original documentation helped. The instruction booklet that came with my watch actually calls it a GB B·I·Time.

So Bi-Time isn't a modern nickname or something invented by sellers. It was GB's own terminology.

Quartz, But Not Quite as Simple as It Sounds

This is where the watch became much more interesting.

The Dahl uses an ETA quartz movement as its base. Based on photographs of a disassembled example, we can safely place it within the ETA 955 series, although I don't yet have enough evidence to claim the exact caliber.

But the jumping-hour mechanism isn't simply a standard ETA function.

A watchmaker and collector known as Crazywatches documented the mechanism while working on one. At first glance, he wrote, it appeared to be “a simple jump module fitted onto a common ETA quartz movement.”

After examining it, his opinion changed considerably.

He described it as an uncommon and surprisingly sophisticated proprietary GB Enigma design, based around a large multilayer actuating star wheel containing a thin spring. Six raised “wings” on the inner edge of the hour disc interact with a semi-rotating dual lever that releases the disc and prevents it from advancing too far.

He later described the system as “pretty overengineered and complex despite the limited number of parts.”

I rather like that description.

So yes, it is a quartz watch. But the quartz movement is effectively the engine driving a rather clever mechanical jumping-hour mechanism developed specifically for the watch.

For someone who normally prefers mechanical watches, that makes the Dahl much easier to love.

Number 800

The original instruction booklet provided another little discovery.

GB explains that every Bi-Time carries an identification number engraved on the side of the case. The first digit is the serial code, followed by the individual serial number.

Mine is engraved:

0.800

That means serial code 0, serial number 800.

Normally that would have been a nice little detail and probably the end of the investigation.

It wasn't.

The Khanjar

On the back of my watch is the crowned Khanjar, the national emblem of Oman, together with “CREATED BY GIANNI BULGARI.”

Omani-signed watches have a fascinating history. During the reign of Sultan Qaboos bin Said Al Said, watches were commissioned and presented as gifts to officials, military personnel, dignitaries and others. Famous examples exist from Rolex, Omega, Patek Philippe and several other manufacturers.

But an emblem alone isn't enough for me to invent a provenance.

Fortunately, this watch came with something much better.

Inside the original set is a presentation card carrying the same Omani emblem. Translated into English, it reads:

“By Special Order of His Majesty The Sultan Qaboos Bin Said Al Said

With Best Regards

Minister of the Royal Diwan”

You can see the original card in the cover photo, here is an image of a translated card, created by AI:

That changes things considerably.

It's surely not the “Sultan Qaboos's watch.” There is no evidence that he personally owned or wore it, nor do I know who originally received this particular example.

What the surviving documentation does appear to establish is something much more precise: this GB Enigma was specially ordered under Sultan Qaboos and presented through the Royal Diwan.

And unlike an isolated watch that has appeared decades later with a Khanjar engraved on its case, this one still has its original GB documentation, guarantee material, presentation card and box.

There is one more reason this watch matters to me, and it has nothing to do with Oman, provenance or rarity.

I simply think it is beautiful.

I'm normally reluctant to buy quartz watches, but the Dahl works exceptionally well as one. It has the visual theatre of a jumping hour without the worry of wearing a complicated vintage mechanical watch every day. It feels solid, the integrated bracelet is excellent, and that strange horseshoe design gives it a personality of its own.

It has also become one of the most beautiful jumping hours in my collection, in my opinion.

I bought it because I liked the design.

Then I discovered Gianni Bulgari's story. Then the Dahl name. Then the unusual proprietary jumping mechanism. Then serial number 800. And finally the Omani provenance and the original Royal Diwan presentation card.

That's one of the things I enjoy most about collecting old watches.

Sometimes the watch is only the beginning of the story.

If you, like me, spend enough time hunting affordable Swiss jumping hour watches from the 1970s, sooner than later you will encounter a pin-lever movement.

I certainly have. Many of the inexpensive digital-display watches from this period used them, which makes the pin-lever an important part of the story of the jumping hour revival of the 1970s. The British Museum even preserves a Swiss digital wristwatch dating from 1972 to 1978 with a pin-pallet escapement, so this wasn't limited to obscure collector lore.

The idea, however, was already more than a century old.

In 1834, Swiss clockmaker L. Peron developed a pin-anchor escapement. Georges-Frédéric Roskopf took that idea further in 1867 when developing the inexpensive watch that became associated with his name. His goal was straightforward: make a mechanical watch that could be manufactured cheaply enough for ordinary people to afford. The Science Museum describes Roskopf's watch as the first satisfactory cheap watch and notes that the design was copied extensively in Switzerland.

That philosophy fits remarkably well with the jumping hour watches of a century later. During the 1970s, manufacturers could combine adventurous cases and mechanical digital displays with inexpensive movements and still produce relatively affordable watches. For the smaller Swiss brands whose jump hours I collect, the pin-lever was a very practical solution.

Its long career eventually came to an end for a fairly obvious reason: quartz.

By the late 1970s and into the 1980s, quartz could provide far greater accuracy at very low cost. The Seiko Museum notes that pin-lever watches virtually disappeared as cheaper quartz watches became popular. The Swiss lever wasn't really the movement that "replaced" the pin-lever at this point. It had already existed alongside it, in better-quality mechanical watches. Quartz simply took over the inexpensive mass-market role that pin-lever movements had filled so successfully.

So what is actually different?

Both are lever escapements, but their construction is not identical.

In a Swiss lever escapement, the escape wheel alternately locks against two shaped jewel pallets mounted in a pivoting pallet fork. As the escapement unlocks, impulse is transmitted through the pallet system and the fork to the roller jewel attached to the balance. The familiar Swiss club-tooth form evolved from Thomas Mudge's detached lever escapement of around 1756 and became dominant because its geometry reduced wear and allowed accurate adjustment of the pallet stones.

A Roskopf-type pin-lever simplifies that system. Instead of shaped jewel pallets, hardened steel pins mounted on the lever interact with a differently shaped escape wheel. British Museum examples also show the characteristic long lever, steel pallet pins and a separate impulse finger. These choices made the escapement cheaper to manufacture, but with more wear and less potential precision than a good jeweled Swiss lever.

There is also an interesting ancestor worth mentioning. Around 1715, George Graham developed the deadbeat escapement for precision pendulum clocks. Thomas Mudge had trained under Graham and later adapted ideas from the deadbeat principle when creating his detached lever escapement for watches. Mudge inserted a lever between the escape wheel and balance, reducing the direct interaction and friction that made the clock escapement unsuitable for a portable watch. That development eventually led to the Swiss lever we know today.

There are many other escapements in horological history, from the verge and cylinder to the marine chronometer's detent and, much later, George Daniels' co-axial. But for the watches most of us encounter, the comparison between pin-lever and Swiss lever is the important one.

I don't consider a pin-lever movement a sign of a bad watch. It tells me what the watch was designed to be. These weren't meant to compete with high-end Swiss movements. They were designed to be inexpensive, functional mechanical watches, and they helped put some wonderfully eccentric jumping hours onto people's wrists.

More than fifty years later, that's precisely why I find them interesting.

Sources:

The lever escapement - The Seiko Museum

Pin-lever -Science Museum

Roskopf pin-pallet movements — British Museum

One of the questions I get asked most often is why one jumping hour watch is worth around $1,500 while another can sell for well over $100,000. At first, the answer seems obvious. It must be the brand, or perhaps simply rarity. After years of collecting, I've come to believe the answer is much more interesting. Rarity is only the starting point. Take two watches I know well: the Spaceman and the TDBK automatic jumping hour chronograph.

Both were sold under numerous Swiss brand names during the 1960s and 1970s, and both can be remarkably difficult to find today. I own two Tressa Spacemans and four Mondia examples of the TDBK, so I know from experience how long the search can take. Yet despite their scarcity, excellent examples generally remain in the low thousands of dollars.

Now compare that with the Rolex Prince Jump Hour.

Rolex is arguably the most recognizable name in watchmaking today, and the Prince is a genuinely rare model from the late 1930s. Interestingly, Rolex had not yet become the global luxury powerhouse we know today when the Prince was produced. Much of the brand's prestige was built in the decades that followed. Even so, today's Rolex name undoubtedly adds to the watch's desirability. Yet a rare Rolex Prince Jump Hour still sells for far less than the most celebrated vintage jumping hour watches from Patek Philippe, Cartier or Audemars Piguet. That comparison says a lot about how collectors think. Brand and rarity both matter, but neither is enough on its own. One change I've noticed over the years is that collectors have started paying much closer attention to the people behind a watch. A respected watchmaker or designer can sometimes influence desirability almost as much as the name on the dial. Daniel Roth is a perfect example. So is François-Paul Journe, whose early work on the Chaumet Pléiade Jump Hour has made that watch highly sought after. The same applies to Gérald Genta. While some of his quartz watches remain relatively affordable, his most important designs have become some of the most collectible watches in the world. In each case, collectors are rewarding the creator as much as the brand. Technical quality also plays an important role. The finest vintage jumping hour watches were often built to a much higher standard, with better movements, superior finishing and greater attention to detail. Add historical importance, originality, provenance and strong collector demand, and you have the ingredients that create exceptional value. The longer I collect, the less interested I become in asking how rare a watch is. I'm much more interested in understanding why collectors value it. Sometimes the answer is the manufacturer. Sometimes it's the watchmaker, the designer or the movement itself. Sometimes it's the role the watch played in the history of the complication. Those are the watches that keep me searching. Collector's Note The comments about the Spaceman and the TDBK automatic jumping hour chronograph are based on my own collecting experience, having owned multiple examples of both models. The pricing observations reflect long-term market observation and discussions with other collectors, including Ruud, rather than fixed market values. References • Phillips Auctions, Chaumet Pléiade Jump Hour auction result, highlighting the early François-Paul Journe connection. • Phillips, Christie's and Monaco Legend Auctions, auction archives for vintage jumping hour watches by Patek Philippe, Cartier and Audemars Piguet. • Contemporary Chrono24 dealer listings for the Rolex Prince Jump Hour. Asking prices are used only as an indication of the current market and should not be interpreted as realized sale prices.

The Thrill of the Hunt If there's one thing collecting jumping hour watches has taught me, it's that the best finds almost never appear when I'm actively looking for them. They usually show up when I least expect them: hidden in a poorly photographed online auction, sitting in a small antique shop, or buried deep in pages of unrelated listings. Those are the moments that make the pulse quicken. Every collector knows the feeling—could this really be what I think it is? Part of the appeal is that jumping hour watches have always been something of a niche within watchmaking. Unlike conventional three-hand watches, they were produced by relatively few manufacturers, and many of the most interesting examples came from independent Swiss brands during the late 1960s and 1970s. When much of the Swiss watch industry was disrupted during the economic and technological upheaval commonly known as the Quartz Crisis, many of those brands disappeared, leaving their watches as reminders of a remarkably creative era. Over the years I've learned that patience is probably the most valuable tool a collector owns. I've walked away from watches that didn't feel quite right, only to find a better example months later. It isn't always easy, but it almost always pays off. Looking back, I realize I'm collecting more than watches. Every piece carries the memory of where I found it, the research that led me to it, and the excitement of recognizing something special before anyone else. That's the part of collecting that never gets old. Further reading Stephen Foskett, "Debunking the Quartz Crisis," Europa Star (2022). Chris Antzoulis, "A Guide to the Jump Hour Complication," European Watch Company Journal (2026), for a concise overview of the history of the complication.

Buying a Name or Buying a Heritage? Not every watch carrying a historic name has a historic lineage. Some famous brands disappeared decades ago during the Quartz Crisis. Years later, the trademarks were purchased by completely unrelated companies, which now produce new watches under the original name. That doesn't automatically make the watches bad. But it does mean they're part of a different story. Compare that with brands such as Patek Philippe or Cartier, whose modern jumping hour watches are a continuation of their own uninterrupted history. Then consider brands that have been revived only as trademarks. The watches may be attractive, well made, and enjoyable to own, but they don't have the same historical continuity. For collectors, that's an important distinction.

Are Chinese Jumping Hour Watches Worth Buying? Absolutely. As long as you know what you're buying. Modern Chinese manufacturers have introduced thousands of collectors to the jumping hour complication at prices that would have been unthinkable twenty years ago. Some are original designs. Some clearly borrow inspiration from vintage Swiss watches. Some offer remarkable value, while others cut corners in finishing or quality control. Like watches from any country, they're not all the same. For many collectors, an affordable Chinese jumping hour becomes the gateway into vintage Swiss collecting. And there's nothing wrong with that. Collecting should be driven by curiosity, not by price.

Browse enough vintage catalogues from the 1970s and you'll notice something interesting. Many brands didn't advertise these watches as "jumping hours." They called them Digital Watches. Today that sounds strange because we associate the word digital with quartz electronics. Back then, the word simply referred to the display. These watches showed numbers instead of hands, making them "digital" despite being entirely mechanical. It's a small detail, but it says a lot about the era. Swiss manufacturers weren't just selling a different way of telling time. They were trying to convince customers that mechanical watches could still feel like the future.