L.Leroy Split-Seconds Chronometer Chronograph – 1912


Considering the exceptional well preserved condition and the fact that it is accompanied by its original hardwood protection box and the extract of archives issued by the Besançon Observatory, we say with confidence that this is a rare opportunity to enrich your collection with one of the finer rattrapante chronometer pocket watches offered for sale at the moment. Scroll down to read more about this exceptional piece.

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Offered for sale is a scarce and highly interesting pocket watch by L. Leroy et Cie – Paris.
This timepiece features a high precision chronometer movement with highly interesting splits-seconds/rattrapante complication made out of the highest standards used for scientific purposes.

Considering the exceptional well preserved condition and the fact that it is accompanied by its original hardwood protection box and the extract of archives issued by the Besançon Observatory, we say with confidence that this is a rare opportunity to enrich your collection with one of the finer rattrapante chronometer pocket watches offered for sale at the moment.

Leroy is a traditional watch brand and beneficiary of an extraordinary inheritance which has been handed down from generation to generation ever since 1747, the year when Basile Le Roy began his apprenticeship with Sr. Quentin, master watchmaker in Paris.
It’s workshops, officially installed in the arcades of the Palais Royal in 1785, have written some of the most beautiful pages in the history of French watchmaking and timekeeping, drawing deeply on the passion of two dynasties of craftsmen whose genius has been inspired as much by the applied arts as by science.

We thank the observatory of Besançon for the information provided. The Observatory certificate issued for this example is included in the sale, as well as a photograph of the pages archive book (see pictures).

The presented watch features an immaculate white enamel dial with black Arabic hour and minute indication. The aesthetically pleasing dial is perfectly balanced in sizing of markers, placement of signature and the use of large sub-dials. All this together with the perfectly manufactured golden spade hands and blued steel chronograph hands fitted in the large and heavy silver casing with subtle accents of rose gold result in an incredibly attractive and intriguing timepiece.
Note that the full watch including the hands, crown and bow are completely unrestored and remain in exceptionally good condition.

The silver case features five ‘crab’ hallmark indicating that the case was produced in Paris (1838 – 1962) accompanied by two makers hallmarks. The case and movement are both stamped with the serial number 9500, which is confirmed by the extract of the Observatory. The case shows normal signs of wear (superficial scratches), no further dents or faults. All lids closing tightly.

The breathtaking movement features stunning mirror polished bridges, large red rubies, a ‘vipers head’ stamp and a large ‘Guillaume’ balance (see below to read more about this special balance wheel and the origin of the ‘vipers head hallmark’). The movement, as expected, runs with incredible accuracy as the time grapher indicates the movement is running only one second short every 24 hours (-1s/d).

‘The Viper Emblem’: Represented by the head of the reptile – certifies a nested mechanical watch as a “stopwatch”, provided that it meets the requirements of ISO 3159 for reliability and accuracy. The watches tested at the Observatoire de Besançon are tested for sixteen days, during which time they are placed in five successive positions and undergo three different temperatures. Only the best timepieces come out of this fire baptism successfully.
The peculiarity of vipers Hallmark, in comparison with other existing hallmarks (independent or belonging to watch brands), is to certify completed watches, as they will be marketed, and not movements alone. This specificity allows the Observatory – and its head viper – to ensure an absolute level of quality, without risking a possible disruption of movement at the time of its nesting. In this sense, the Viper Punch is a truly definitive certification; and the bulletin of march, issued at the end of the tests, thus validates a total reliability.

‘Guillaume Balance Wheel’: Nobel Prize winning physicist Charles Édouard Guillaume had managed to create accurate measuring devices with specific nickel alloys. Under extreme temperature changes, many precision instruments would expand and contract, skewing any measurements made. At least until Guillaume discovered the nickel-steel alloys of invar and elinvar.
Invar had a near zero coefficient of thermal expansion, while elinvar had almost no modulus of elasticity, which meant any object would experience only microscopic change in size from heat and cold. As the son of a horologist, Guillaume applied his discoveries to marine chronometers, coating the balance wheel in a variation of invar, allowing the ticks to remain in a better matching pattern.

According to the extract we find that this specific example, one of very few, was given a certificate in the ‘1st class’ category. The watch was delivered to the observatory on March 18, 1912.
Beneath you will find the deviations in seconds per day on different positions;

– Valeur maximale de la marche moyenne pendant les épreuves: 4,62 s/d
– Maximum value of the average rate during the tests: 4,62 s/d

– Valeur Maximale de l’écart moyen pour une meme periode 0,37 s/d
– Maximum value of the average deviation for the same period 0,37 s/d

– Valeur maximale de la difference de marche moyenne entre deux periodes non thermiques 1,58 s/d
– Maximum value of the average path difference between two non-thermal periods 1.58 s/d

– Variation ou difference de marge moyenne être les deux plats 0,20 s/d
– Average margin variation or difference on both sides 0.20 s/d

– Variation ou difference de marche moyenne du plat au pendu 0,00 s/d
– Average variation or difference in rate from flat to hanged 0,00 s/d

– Ecart moyen ‘a’ de la marche diurne ±0,19 s/d
– Mean deviation ‘a’ of the diurnal rate ±0.19 s/d

– Ecart moyen ’b’ correspondant a un changement de position ±0,34 s/d
– Average deviation ‘b’ corresponding to a change of position ±0.34 s/d

– Erreur de compensation ±0,003 s/d
– Compensation error ±0.003 s/d

– Reprise de marche ‘ ‘ ou difference de marche moyenne entre les periodes extremes -0,64 s/d
– Rate recovery ‘ ’ or average rate difference between the extreme periods -0.64 s/d

– Cette montre a obtenu un bulletin en categorie “1ere classe”.
– This watch has obtained a certificate in the “1st class” category.

The watch is accompanied by its original wooden presentation box which is a treat on its own.
Made out of fine birchwood with sturdy double hinged mechanism this travel/presentation box adds up to this timepiece’s collectability and completeness. Even more so as it will be delivered together with the extract from the archives of the Besançon Observatory indicating the finesse of this true Chronometer time capsule.

More information, pictures and video’s can be send upon request.
Feel free to ask us whatever question you have about this timepiece.

Please note that all our watches are bank stored, therefore we handle a 24 to 48 hour processing time between payment and shipment.





Sterling Silver


151,2 Grams


Split-Seconds / Rattrapante

Year Of Production



56,5mm / 70,5mm / 79,3mm


Original Box & Observatory Records