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The Encyclopedia of Horology

Marine chronometer · Marine chronometer

Longines Marine Chronometer

Partially verified

This marine chronometer, identified by Longines serial number 8278725, was produced in the 1940s. The instrument is housed within a two-body oak box, featuring a brass hinged bowl mounted in a gimballed suspension system. The matte silver dial presents a 24-hour indication with Arabic numerals and an outer minute ring, complemented by a sector display for the 36-hour power reserve. It utilizes blued steel spade hands. The internal mechanism is the caliber 21.29, a 21-jewel movement finished with rhodium plating and fausses côtes decoration. It features a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, a self-compensating Breguet balance-spring, and a cam-type micrometer regulator. The chronometer is accompanied by two keys, and both the dial and movement bear the Longines signature, with the case displaying the serial number.

Longines Marine Chronometer, serial number 8278725, in its gimballed oak box.
Longines Marine Chronometer, serial number 8278725, in its gimballed oak box. — Antiquorum. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
catalog.antiquorum.swiss
Category
Marine chronometer · Marine chronometer
Maker / attribution
Longines
Reference
Cal. 21.29
Catalogue / lot identifier
118
Source-reported date
1940s
Source-reported place
Switzerland
Source-reported serial
8278725

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Case and Dial Construction

The chronometer is enclosed in a two-body oak case, constructed with brass hinges and a dedicated brass bowl mounted via a gimballed suspension to maintain level in marine environments. The case exterior dimensions are recorded as 15 x 15 x 10 cm, while the internal bowl measures 90 mm in diameter. Two keys are included for winding and adjustment.

The matte silver dial displays a concentric 24-hour numerical sequence, which is supplemented by an outer minute ring and a specific sector for the up-and-down power reserve indication. Time is read using blued steel spade-pattern hands, which provide contrast against the silver surface of the dial. The dial itself is signed by the manufacturer.

Evidence for this section
  • “Two-body, made from oak, brass hinged, brass bowl and gimballed suspension.”
  • “Matte silver with Arabic numerals, concentric 24-hour indication, outer minute ring, sector for the up-and-down indication. Blued steel ?spade? hands.”
  • “Dim. Bowl 90 mm. Box 15 x 15 x 10 cm.”

Movement and Escapement

The movement powering this instrument is the Longines Caliber 21.29. It features 21 jewels and a rhodium-plated finish with fausses côtes decorative detailing. The escapement is a straight-line lever type. Technical precision is managed by a monometallic balance adjusted for five positions and temperature, paired with a self-compensating Breguet balance-spring.

Regulation of the rate is performed using a cam-type micrometer regulator, allowing for adjustments to the chronometer’s performance. The movement is signed to verify its origin, and the overall state is reported with a grade of 3, with an overhaul recommended for optimal performance.

Evidence for this section
  • “Cal. 21.29, rhodium-plated, "fausses côtes" decoration, 21 jewels, straight line lever escapement, monometallic balance adjusted to temperature and 5 positions, self-compensating Breguet balance-spring, cam-type micrometer regulator.”
  • “Dial and movement signed, case numbered.”
  • “Overhaul recommended, at buyer's expense”

Signatures and Documentation

The chronometer is formally identified by the Longines serial number 8278725, which is cited on the case. Further authentication is provided by the manufacturer’s signature on the dial and the movement. The item is dated to the 1940s.

Condition reporting provided by the auction description includes grades for the case, movement, and dial, identifying them as generally good, though technical maintenance is advised. The assembly includes two keys used for the operation of the instrument.

Evidence for this section
  • “No. 8278725. Made in the 1940s.”
  • “Accompanied by two keys.”
  • “Dial and movement signed, case numbered.”

Open research questions

  • What specific maritime vessel or institution was this chronometer originally commissioned for?
  • What is the exact year of production within the 1940s for this specific serial number?

Source evidence

Recorded claims and source quotations for Longines Marine Chronometer
FieldSource-reported valueSource quotation
MakerLongines“Longines”
Serial Number8278725“No. 8278725”
MovementCaliber 21.29“Cal. 21.29”
Power Reserve36 hours“36-hour powerreserve”
Case MaterialOak and brass“Two-body, made from oak, brass hinged, brass bowl and gimballed suspension.”
Dial Features24-hour indication“concentric 24-hour indication”
Balance SystemMonometallic“monometallic balance adjusted to temperature and 5 positions”
DimensionsBowl 90mm, Box 15 x 15 x 10 cm“Dim. Bowl 90 mm. Box 15 x 15 x 10 cm.”

Visible details

  • Oak box with brass hardware
  • Gimballed brass mounting
  • 24-hour dial layout
  • Power reserve indicator on dial

Research qualifications

  • Movement overhaul recommended by auction house
  • Specific production year within the 1940s is not defined

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

'Marine Chronometer' Longines, Swiss, No. 8278725. Made in the 1940s. Fine, center-seconds, brass marine chronometer with 36-hour powerreserve and 24-hour dial. Accompanied by two keys.

Reviewed 2026-10-26 · Record 39c3d33041

Terms in this record

Glossary explanations for terms named in this object’s record.

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