Many watch aficionados have been lamenting the fact that many watch movements have gotten bigger over the past two decades. Enter the Jaeger-LeCoultre Caliber 101. This is a lesson in miniaturization that some modern brands should take heed of. So, what cutting-edge 2023 technologies were used to produce it? None. It is almost a century old!
The Jaeger-LeCoultre Caliber 101 is an impressive feat of engineering and watchmaking. I have had the privilege of handling several of these, and the scale is uncanny. I will do my best to convey some of the awe I experienced in this article.
Image: Amsterdam Watch Company
Jaeger-LeCoutre Duoplan
Before we get to Caliber 101, we have to back up a bit. JLC’s journey into miniaturization began in the 19th century with Antoine LeCoultre’s invention of the Millionometre. This tool allowed measurements down to one micron. Impressive on its own merit, it would turn out to influence the path of the brand down the line.
Antoine’s grandson Jacques-David LeCoultre merged the family business with French watchmaker Edmond Jaeger in 1903. One of the early projects they tackled together was the Duoplan technology.
The backwinder crown on a slightly larger Cal. 104 — Image: Amsterdam Watch Company
In an effort to scale down watch calibers, the traditional movement architecture was broken in two and stacked. Duoplan, literally meaning “two levels,” was born. The crown was placed flush against the backside, making these so-called “backwinding” movements. The Duoplan technology was specifically designed for jewelry watches. Remember that this was still very much back in the era of pocket watches.
Image: Amsterdam Watch Company
Duoplan Caliber 101
Come 1929, the early Duoplan calibers found their smallest footprint. Caliber 101 was born, pushing the split-level concept to its absolute maximum. Or minimum, I should say. Measuring just