Only Online Auction

Geneva, Dec 08, 2022

LOT 178

L. Leroy & Co.
Chronometer pocket watch, split-seconds chronograph, minute counter, stop-seconds, Bulletin of the Astronomical Observatory of Besançon; silver

CHF 2,000 - 4,000

EUR 2,000 - 4,000 / USD 2,100 - 4,200 / HKD 16,400 - 32,700

Sold: CHF 2,500

Silver, open-face, keyless-winding, round-shaped, pocket chronometer, with subsidiary seconds at 6, stop-seconds (activated by the round push-piece located on the case-band at 9 o’clock), and three horological complications:
· 1/5 second chronograph (activated by the single round-shaped push-piece located on the winding-crown)
· Split-seconds (activated by the olive-shaped push-piece located on the case-band at 11 o’clock)
· 60-minute counter (subsidiary dial at 12 o’clock)

White colour enamel dial, with suspended Arabic numerals; blued steel “Spade” hands.

Case-back polished; cuvette (dome) polished.

19’’’, gilded brass, going barrel, straight-line lever escapement, cut bimetallic compensated Guillaume balance with gold poising screws and blued steel hairspring with terminal curve, polished steel index-regulator; chronograph work on the top plate; split-seconds work mounted under the dial; “viper’s head” stamp of the Besançon Observatory for a First Class Bulletin de marche.

Grading System
Grade: AA

Very good

Case: 3
Movement: 3*


Overhaul recommended, at buyer's expense

Dial: 3-71-01-05


HANDS Original

HANDS Luminous material reapplied

Brand L. Leroy & Cie, Paris (7, boulevard de la Madeleine)

Model “Horloger de la Marine”; having won a First Class Bulletin de marche from the Astronomical Observatory of Besançon

Year  circa 1923

Movement No.  No. 13 416

Case No. No. 14 856 (by Société Générale des monteurs de boîtes d’or, Besançon)

Material  silver

Diameter Ø 54.8 mm.

Caliber 19’’’, straight-line lever escapement, Besançon Observatory seal

Weight 110.4 gr. (approx.)

Signature dial, case and movement


The watch was delivered on July 27, 1923, to Mr. Germain-Alexis Doninelli, “Horloger-mécanicien de l’Observatoire”, Nice (5 bis traverse Longchamp) and paid on August 6, 1923, for the amount of 2 100 francs.

We would like to thank the Leroy Heritage department for kindly providing us with the above-mentioned historical information from the Manufacture’s archives.


Guillaume balance

The Guillaume balance is a compensated bimetallic balance, made of anibal (an alloy of steel and nickel) and brass, after the works of Dr. Charles-Edouard Guillaume (1861-1938), with which the middle-temperature error is practically eliminated. The middle- temperature error (or Dent’s anomaly), is the difference between the rate of a chronometer at the mean temperature and the average of the rates at extreme temperatures. This type of balance was used by the horological manufactories since 1904.