What is a Chronomètre?
There is a very long history of the quest for ultimate timekeeping – the production of a timepiece that can keep precise and accurate time over long periods – a.k.a. Chronometry. Plenty has already been written about the timepieces that were subsequently created in the search for horological perfection, particularly on the importance of marine chronomètres in seaborne navigation. For more broad historical reading on the topic, I can recommend books such as “Wristwatch Chronometers: Mechanical Precision Watches and Their Testing” by Fritz von Osterhausen, “Marine and Pocket Chronometers” by Hans con Bertele, and “The Marine Chronometer: Its History And Development” by Rupert T Gould.
Competitive chronometry extended into wristwatches in the 20th century, and the Swiss watch industry successfully lobbied to introduce laws where a watch needed to pass official precision tests to be called a “chronomètre”. Originally carried out by independent Swiss testing observatories (where methods had slight variations) certification was centralised in 1973 by the foundation of the COSC (Contrôle Officiel Suisse des Chronomètres). Chronometry competitions had become more and more popular, and as such many watch companies were competing with their timepieces to see who could produce the most accurate wristwatch in the world. This includes Universal Genève, who through the 1950s and 1960s were producing a significant number of chronomètre-rated watches. These highly accurate calibers were available throughout much their catalogue, including many of the Polerouter references.
“Chronomètre” rated Polerouters
The Polerouters were given the option to have chronomètre-rated movements throughout the 20-plus year production timeline, from the early “bumper” caliber 138ss references through most of the later Microtor references. We know this from both examining the examples that have surfaced in watch collections, as well as from vintage advertisements from the 1950’s and 1960’s.
What does a Polerouter Chronomètre look like?
It is not immediately obvious to identify a Chronomètre Polerouter, particulary to a non-expert, as the aesthetic differences are very minor. Chronomètre-rated references are visually identical to their non-chronomètre reference counterparts, with only the small and inconspicuous text “Chronomètre” added to the dial. The main differences were of course internal, in the construction and calibration of the calibers that power them. Each had an uniquely numbered movement, which had been tested and certified to have a Chronomètre rating. Like the dial text, these unique 4-digit caliber serial numbers were applied discreetly and varied in location depending on the caliber and its production period.
On 138ss, a 4-digit Chronomètre number was engraved on the train wheel bridge, as below. Some early 215 and 215-9 had their 4-digit number engraved on the barrel bridge, but most often the number appeared on the train wheel bridge. 138ss chronomètre movements were understandably missing the “Unadjusted” text that appeared on their no Chronomètre counterparts. For the Microtors, it was only the US-market calibers that featured “unadjusted” text on the train wheel bridge. All of the other Microtor calibers (both non-chronomètre and chronomètre) for other markets did not have this text.
The Chronomètre testing method for Polerouters seems to have become more rigorous during the Microtor production period. The early Microtors were tested in “2 Positions and Temperature” (below left), whereas the later Microtors were tested in “5 Positions and Temperature” (below right).
How many were made?
We have assembled a database of over 150 UG Chronomètres from within the Polerouter production period. This includes the 138ss and various Microtor calibers that powered Polerouters. Around 20% of these are Polerouters, and the individual movement numbers span a range of approximately 3100 movements. Assuming this is an approximately representative subsample, this would mean there would have been around 500-700 Polerouter Chronomètres produced in total. This is including ALL Polerouter references, from their entire production timeline of 20-plus years. So yes, any reference number Polerouter Chronomètre is quite rare to find, and therefore very collectible.
What are the most common Polerouter Chronomètre references?
So far, the most commonly found Chronomètre-rated Polerouter reference is the 104601-1, followed by the 10357-3. In general, it seems that Chronomètres are more commonly found powering 18k case references than steel or gold-cap/-plate case references. One would assume that since the 18k case references were already in the order of 3x the price of other case materials, then the increased pricing for a Chronomètre caliber was less significant.
