Thin and ultra-thin watches might seem like a boring topic, because you can’t talk about these watches without discussing many of technical details.
It's all about the technical details, as this is an extremely complicated area of watchmaking reserved for the most skilled masters. Yet it's easy to forget about all the technical details when you hold one of these really slim finished pieces in your hands. It's one of those moments when the magic of watchmaking really shines through, which can transform something purely technical into a true emotion.
Thin watches probably elicit the strongest emotional response of all complicated clockwork devices that belong to haute horlogerie. The pinnacle of fine watchmaking is where highly complicated watches meet slim watchmaking. That’s because there would be no highly complicated watches in the art of watchmaking without thin and ultra-thin movements — it's simply unimaginable.
Oddly enough, the characteristic features of the earliest mechanical timepieces manufactured from around the 13th century were their imposing dimensions. The first were turret clocks housed in clock towers, and they were usually made by blacksmiths, hence why they were made of strong iron at a time when no one really cared about how thick the clocks were.
Early portable or personal timepieces appeared at the beginning of the 16th century and are associated with the legend of Peter Henlein from Nuremberg, who is often hailed as the inventor of the world's first wearable watches known as pomander watches. They're sometimes referred to as the first pocket watches, but that isn't exactly true, because this category of pocket watches wasn't developed by watchmakers until some time later.
It's worth pointing out that Henlein probably shouldn’t be credited with the invention of the first wearable watch, as the Italian architect Filippo Brunelleschi is considered the inventor of the spring-driven clock (around 1410). It was thanks to this invention that the first personal timepieces appeared in the 15th century, powered by a wound mainspring, the earliest of which were chamber clocks or lantern clocks, followed by mantel clocks.
This was the first step towards reducing the size of mechanical clocks, which could hardly have been achieved with a torsion pendulum. What we do have Peter Henlein to thank for is his skillful marketing of portable clocks, and for managing to give these compact clocks by contemporary standards a 40-hour power reserve.
The Melanchthon-Uhr made by Henlein in 1530 is the earliest surviving example of portable clocks from this era, and it offers a good impression of what they were like. You can tell from its shape and design that these timepieces were worn as pendants, attached to belts and necklaces, or attached to dresses as a broach, yet these spherical cases were around 50 mm thick. The movements and the timepieces housing them generally became thinner as watchmaking technology progressed.
The movements of small Baroque mantel alarm clocks from the 17th century were usually around 60 mm thick, while the movements of portable clocks from the same period were just over 30 mm. A seemingly insignificant event in the history of watchmaking technology occurred toward the end of the 18th century. In 1766, King Charles II of England and Scotland ordered his court to wear waistcoats known as Persian vests at the time. It’s believed that he wanted to wean the aristocrats off dressing with a decadent French fashion sense, in clothes dripping with ornaments.
The thick waistcoats which emphasized the cut spread across England and then throughout Europe, and it became fashionable to carry watches in the waistcoat pockets, which is when they rightly became known as pocket watches. Watchmakers had no other choice but to adhere and adapt to the new rules as much as they possibly could by making smaller watches, and most importantly thinner watches.
The English master clockmaker Daniel Quare was influenced by this fashion at the beginning of the 18th century, who went on to make relatively thin watches and invent the minute repeater. Further progress in making watch movements thinner is attributed to the work of French master watchmaker Jean-Antoine Lépine.
The caliber Lépine designed in 1764 and 1765 was built without a fusee. Its balance wheel was placed on a single plate along with the main wheel system on one side, the bulky spindle was replaced by a compact cylinder escapement, and bridges were mounted on the back of the movement instead of using a second plate, which also made it easier to assemble the watch (and to disassemble it for servicing).
Lépine's caliber was a real breakthrough. The Lépine Caliber's design made it possible to manufacture significantly slimmer movements and slimmer pocket watches to house them, compared to the design of earlier watches which had used two plates and had the balance wheel positioned outside the top plate.
Abraham-Louis Breguet used the Lépine caliber to manufacture a variety of watches that were simply remarkably thin by contemporary standards, including watches with complicated features. For example, the case of the No. 3306 watch he made in 1819 was only 8 mm thick.
The pinnacle of thin watchmaking was reached at the beginning of the 19th century, when even slimmer watches became fashionable. That was when Swiss watchmakers created small pocket watches and pendent watches with movements using the cylinder escapement, which they managed to slim down to no more than 1.9 mm or even 1.7 mm.
This was mainly thanks to an invention called the bagnolet caliber that the Swiss watchmaker Philippe Samuel Meylan created around the 1830s or 1840s. Meylan's calibers had an interesting feature — the dial for reading the time was placed on the same side of the movement as the bridges, and the thinnest pieces had a movement plate which doubled up as the case back, making it possible to create an even thinner watch.
Another Swiss watchmaker who specialized in making thin watches at the beginning of the 19th century was Jean-François Bautte, who founded the company Girard-Perregaux. It wouldn't be right to say that thin watches had a significant measurable share of the market at that time. That share was occupied by the exotic rarities manufactured to demonstrate a watchmaker's outstanding skill.
It took a lot of time to manufacture thin watches, which was spent on gradually slimming down the width of each component in the movement and adjusting how they function, as a thinner movement also meant less space separating the moving parts. Far from every watch buyer was informed about the real value of these watches, which is why thin watches were often perceived as unreasonably expensive, and are even still perceived as such.
There was a resurgence of interest in thin watches and movements at the end of the 19th century, when a number of watch firms began designing and producing thin and ultra-thin calibers based on the lever escapement technology which had already been developed by that time. For example, Haas Neveux & Cie unveiled a 2 mm movement in 1896, which was the thinnest movement on the market at that point in time.
It was later pared down to 1.3 mm. LeCoultre released the Caliber 145 in 1907, which was 1.38 mm thick. Other firms that specialized in making exquisitely thin pocket watches at the beginning of the 20th century were Vacheron Constantin, C. H. Meylan, Touchon, Henry Capt, and Cartier etc.
In 1921, Audemars Piguet made a number of pocket watches based on the ultra-thin Caliber 17SVF, with movements that were 1.32 mm thick. The firm could have gone further though in terms of technical complexity, and to ensure a sufficient level of reliability. Vacheron Constantin struggled with the same challenges, and the company released just three pocket watches with a 0.9 mm movement in 1931.
Apart from calibers with a simple functionality, ultra-thin movements were designed at the beginning of the 20th century with additional complicated functions, including chronographs and minute repeaters. In 1910, LeCoultre launched the ultra-thin Caliber 19 RMCCVEP with a minute repeater and chronograph in a movement that was just 3.55 mm thick. The era of pocket watches ended as watchmakers gradually began taking a greater interest in wristwatches — read about this transition in Part Two.