O for Observatory

In a partnership between Phillips, LVMH-owned Zenith, and renowned independent watchmaker, Kari Voutilainen, a never-before-sold series of vintage Zenith 135-O movements (regulated by Charles Fleck and René Gygax in the mid-twentieth century for observatory trials) are being expertly finished, cased, and brought to market.

Featuring a stunted escape wheel to accommodate a larger balance wheel for improved rate stability, the movement architecture is akin to the Peseux 260, another vintage, observatory-grade chronometer, which Voutilainen based his own series of Observatoire timepieces on. However, unlike the Peseux 260, the Zenith 135 has an extra pinion in the gear train for a center-seconds hand, and can readily be set up to indicate either central seconds or subsidiary seconds. Whereas the Peseux 260 is architected specifically for a sub-seconds layout. That said, like Voutilainen's Observatoire timepieces and as with the Zenith 135-equipped timepieces that have preceded this set, Zenith has opted to go with sub-seconds.

It's also worth noting that, while Voutilainen converted the Peseux 260 to a free-sprung balance system for improved isochronism, he was very intentional about his team leaving the regulating components in the Zenith 135-O calibers they received exactly as they found them:

“The persons working on these movements were the best watchmakers at the time. They had the know-how to make things precise. That precision doesn’t disappear after 70 years. Our duty was not to touch that performance.”

Image credit Voutilainen / Zenith SA

Rexhep Rexhepi Chronomètre Contemporain II

The original Chronomètre Contemporain by Rexhep Rexhepi, which debuted in 2018, was a masterclass in movement layout and finishing. The follow-up from Rexhepi packs greater complexity under the hood, while retaining its visual identity on the dial side.

Surpassing the movement that preceded it in specs on paper, that increased complexity lends the new movement an altogether different visual appeal that falls a stride short of the supreme elegance of its forebearer. The supersized breadth of the anglage and oversized spokes on the balance wheel seem almost caricature-like when posed next to the original.

I would be interested to hear more from Rexhepi himself about the thinking that went into bifurcating power delivery and, in particular, the changes to the balance wheel. In addition to the unusually large spokes, the modifications to the variable-inertia weights on the balance render it moderately more tedious to make precise timing adjustments in such tight quarters. Robin Nooy, over at Monochrome, has reported that the balance screws are responsible for the 60% increase in inertia at the balance wheel. However, it is clearly the increased girth of those spokes that account for the majority of that increase. Ideally, though, you want to move as much of that weight as possible to the outer rim, or felloe, of the balance wheel to optimize rate stability. Time will tell if this new balance design has staying power or whether it will mirror the trajectory of Voutilainen's Carbontime Fused Quartz Balance in the Rexhepi timeline.

At the end of the day, the execution of the finishing remains world class and it retains a free-sprung balance, so it's still got it where it counts.

Image credit Akrivia