Feature: How The World’s Smallest Movement Was Made (Part 2)

Last time, we discovered how the partnership of Edmond Jaeger and Jacques-David LeCoultre would form to bring cutting-edge design and manufacture together in the shape of the world’s thinnest movement, the calibre 145. But that was only the beginning for the duo—the real challenge still lay ahead: to design and build the world’s smallest movement, the calibre 101.

Although Edmond Jaeger had joined Jacques-David LeCoultre to form the Jaeger-LeCoultre watch company, Jaeger’s other concerns were still thriving. One of those surrounded the growing automotive industry, in the design, manufacture and supply of dash instruments like tachometers and speedometers.

By the middle of the 20th century, Jaeger supplied instruments to no less than Citroën, Panhard, Renault, Bugatti, Delage, Aston Martin, Triumph, Rover, Vauxhall and Bentley, as well as working in partnership with suppliers to Ferrari, Fiat and Alfa Romeo. But, unfortunately, Edmond Jaeger would not get to see this incredible success himself, because he had fallen gravely ill.

It was a critical time for Jaeger-LeCoultre, having signed an exclusive deal to provide Cartier with miniaturised movements for its jewellery watches for the next fifteen years. The quest for the smallest movement in the world was no longer just a challenge between friends—it would decide the fate of the company altogether.

The company Jaeger, despite Edmond Jaeger’s ill health, had to go on. Jaeger and co-founder Edmond Audemars—a distant cousin of Audemars Piguet co-founder Jules Louis Audemars, record-breaking aviator and the first to fly from Paris to Berlin, and beneficiary of pioneering World War 1 pilot Roland Garros’ will—then decided to appoint one Henri Rodanet as Technical Director of Jaeger.

The Jaeger-LeCoultre calibre 101 is the world’s smallest watch movement

Rodanet came from a line of Parisian watchmakers, and was a man plagued by misery. His father died when he was four, his mother when he was eight, and one of his sisters when he was nine. The remainder of his family moved in with their uncle, a watchmaker, who saw in Rodanet a talent and enrolled him in watchmaking school. His flair was quickly spotted by Edmond Jaeger, who brought him into the fold, and soon Rodanet was promoted into management.

But World War 1 struck, and Rodanet was mobilised onto the front line as a British Army interpreter. Yet despite the ongoing war, he found time to continue with his designs, making notes and penning sketches whenever he could, developing special instruments for the Allied effort. He alone would amass over 500 patents.

Wartime instrumentation was not the only thing on Rodanet’s mind, however, as the contract with Cartier loomed. On his return from the front, he received his promotion to Technical Director, and was tasked with the challenge of saving not only the reputation of the newly formed Jaeger-LeCoultre, but the business itself.

Rodanet put his technical nous to work, distilling the very essence of the mechanical movement and reassembling it in his mind. He knew that if he wanted to retain the accuracy for which LeCoultre was famous, the balance wheel of the watch, its beating heart, could not be shrunk—at least, not with the technology they possessed at the time. This one component was the seemingly insurmountable wall placed in front of him, the limitation that meant a traditional movement could shrink no further. But he wasn’t to design a traditional movement—he had a better idea.

The Jaeger-LeCoultre calibre 101 is 14mm in length, 4.8mm in width and 3.4mm thick

The idea took Rodanet several years to develop, working with the best minds at Jaeger-LeCoultre to push material technology to its maximum. What he proposed was unlike anything ever seen before, and its realisation was not going to happen overnight. A basic mechanical movement is typically made up of the following: a winding mechanism to add power, a mainspring to store it, a gear train to subdivide that power into hours and minutes and feed it to the hands, and an escapement to control the unwinding mainspring and regulate its power.

These components are usually seated along a single plane, one after the other, to ensure the movement is as thin as possible, maximising the width of the watch’s display to fit it all in. But Jacques-David LeCoultre had demonstrated with his advanced manufacturing techniques that the construction of a movement need no longer be determined by the constraints of thickness.

So, here was Rodanet’s idea: take the escapement and the winding mechanism and seat them side-by-side, not too dissimilarly to a traditional movement, but then bundle up the mainspring and the gear train and seat them directly underneath on an entirely new level. Now the movement could be as wide as just the balance wheel, and thanks to the technical achievements of the company’s manufacturing abilities, it could remain at a reasonable thickness as well.

This new movement, called the Duoplan, was the first to offer the performance of a larger movement in a small package. So proud were Jaeger-LeCoultre of this mechanism that, for just an additional two percent over the asking price, customers could purchase a comprehensive warranty that covered not just manufacturing defects, but water damage and even theft!

The Jaeger-LeCoultre calibre 101 can be found within the 101 Feuille bracelet and 101 Ring

A success for Jaeger-LeCoultre, the Duoplan revolutionised miniature watchmaking—but Rodanet knew there was more to come. Successively he developed iteration after iteration, rearranging the components, challenging the manufacture, finding every last micron of wasted space and eliminating it. There were four iterations in total, with the fourth and final, released in 1929, the smallest Duoplan of all: the calibre 101.

At just 14mm in length, 4.8mm in width and a scarcely believable 3.4mm thick, the calibre 101 became—and still is—the smallest mechanical movement ever made. With individual components weighing in the tenths of milligrams, the total weight is barely a single gram. Yet thanks to the combined expertise of companies Jaeger and LeCoultre, this tiny device still operates at a thoroughly contemporary 21,600 beats per hour, delivering the accuracy and usability expected of this prestigious organisation.

And there are no two examples of this record-breaking movement alike. For the calibre 101 to work, every single one if its ninety-eight components must be custom built, unique for every example. It’s this dedication to extreme performance that makes watches like the 101 Feuille bracelet, similar to the one worn by Queen Elizabeth II during her coronation, and the incredible 101 Ring to become possible. It was a rare moment of collaborating genius that has never been replicated since.

So now when you hear Jaeger-LeCoultre referred to as the watchmaker’s watchmaker, you’ll have a better understanding of how this incredible company came to earn that incredible reputation, how a meeting of minds and the thrill of a challenge brought the future of the watchmaking industry closer than ever before. The calibre 101 is not just a movement—it’s a line in the sand, the moment when excellent became exceptional, but most of all, an emblem of what can be achieved when we work together.

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