L. Leroy & Cie Oversized Pocket Chronometer No. 18902
Record status
Individual type · partial
Period
1939
This L. Leroy & Cie pocket chronometer, movement number 18902, is an oversized, keyless-winding scientific instrument featuring a split-seconds chronograph and an instantaneous 30-minute counter.
Constructed with a 66.3 mm silver open-face case, the watch contains a 21-ligne gilded brass movement with a straight-line lever escapement and a bimetallic compensated Guillaume balance with gold poising screws. The watch was adjusted by Albert Dessay and holds a First Class Bulletin de marche from the Astronomical Observatory of Besançon for the 1939 competition in the category A, "Chronométrie Epreuves Sportives."
It was delivered in 1941 to the Institute of Meteorology and Physics of the Globe of Algeria, serving as a tool for seismic and geophysical study. The watch is presented with a copy of its Observatory bulletin, a maker's archive extract, and a custom wooden box.
Evidence at a glance
- Linked sources
- 1
- Photograph views
- 1
- Catalogue references
- 0
Counts describe this entry’s documentation, not authenticity, rarity or completeness. Photographs may show one specimen; check each caption and licence.
Technical characteristics
- Type
- Split-seconds pocket chronometer
- Maker
- L. Leroy & Cie
- Balance
- Guillaume balance
- Adjustment
- Albert Dessay
- Case Number
- 27205
- Complications
- 1/10 second chronograph, split-seconds, 30-minute counter
- Movement Type
- 21 ligne gilded brass
- Place recorded
- France
- Movement Number
- 18902
- Date of delivery
- December 18, 1941
- Maker / attribution
- L. Leroy & Cie
Design
- Case and Dial
- The timepiece is housed in a 66.3 mm silver open-face case. The dial is white enamel and displays suspended Arabic numerals with blued steel "Spade" hands. A 30-minute register is positioned at the 12 o'clock marker, while constant seconds are tracked in a subsidiary dial at the 6 o'clock position. A round-shaped push-piece for the chronograph function is integrated into the winding crown. A secondary, rectangular-shaped push-piece on the case band at the 10:30 position controls the split-seconds function. The watch includes a snap-on case back and an engraved cuvette featuring the movement's technical specifications.
- Visible features
- • Case diameter is 66.3 mm. • Dial features a subsidiary 30-minute counter at 12 o'clock. • Split-seconds pusher is located on the case band at 10:30. • Movement features a viper's head observatory stamp.
- Movement and Chronometry
- The 21-ligne gilded brass movement is fitted with a straight-line lever escapement and a Guillaume balance, which uses anibal and brass to minimize middle-temperature error. The balance incorporates gold poising screws and a blued steel hairspring with a terminal curve. The movement was adjusted by the precision timer Albert Dessay of Besançon. The caliber includes a chronograph mechanism on the top plate and split-seconds work located under the dial. It bears the "viper's head" stamp from the Besançon Observatory, signifying it received a First Class Bulletin de marche in the 1939 "Chronométrie Epreuves Sportives" competition.
- Provenance and Documentation
- The watch was delivered to the Institute of Meteorology and Physics of the Globe of Algeria on December 18, 1941, for a sum of 10,000 francs. It functioned as a scientific instrument for seismology and geomagnetism research. The provenance documentation includes a copy of the Bulletin from the Astronomical Observatory of Besançon and an L. Leroy archive extract. The piece also comes with a custom wooden storage box.
Identification
- Serial number
- 18902
- Source note
- Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.
Catalogue references
No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.
Research required
- Research required: The exact origin of the ebauche is unconfirmed, though attributed to the Vallée de Joux.
- Research required: The extent of current functionality for the high-frequency complication remains unverified.