Asmus Johanneson 56-Hour Ship's Marine Chronometer
Record status
Individual type · partial
Period
1900 - 1920
According to dealer documentation, this antique marine chronometer is signed by London maker Asmus Johanneson and houses a 56-hour movement. The instrument is gimbal-mounted within a three-tier brass-bound mahogany deck box featuring recessed side handles and a locking mechanism.
Its engraved, silvered dial displays Roman numeral hours, a subsidary seconds register, and a power reserve state-of-wind indicator positioned below twelve o'clock. An original ratcheted winding key is docked in the upper corner of the case interior. The seller dates the chronometer to circa 1900–1920, with external dimensions measuring 19 cm in height, 19 cm in width, and 17 cm in depth.
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
- Ship's marine chronometer
- Maker
- Asmus Johanneson of London
- Movement
- 56-hour movement in gimbals with locking lever
- Place recorded
- United Kingdom
- Dial description
- Engraved and silvered dial with seconds and up-and-down registers
- Case construction
- Three-tier mahogany case bound in brass
- Maker / attribution
- Asmus Johanneson
- Dealer Internal Reference
- 1618
Design
- Visible features
- • Chronometer movement bowl mounted in a brass gimbal suspension within an open mahogany box • Silvered dial with Roman numerals, a subdial for running seconds, and an up-and-down state-of-wind indicator below XII • Gimbal locking lever and corner-mounted winding key clearly visible in the case interior • Brass corner reinforcements, hinges, keyhole escutcheon, and recessed side plate on the mahogany case
- Dial and Suspension
- The instrument features a brass bowl suspended within a gimbal system held in an open mahogany deck box. The silvered dial incorporates black Roman numeral hour markers, an auxiliary running seconds register, and an "Up-and-Down" state-of-wind indicator dial set directly below Roman numeral XII. Mounted adjacent to the suspension ring in the top corner of the box interior is a slotted ratcheted winding key, while a gimbal locking lever is positioned along the side of the mounting ring to secure the mechanism during transport.
- Box Construction and Hardware
- The chronometer is housed within a three-tier mahogany box fitted with protective brass corner reinforcements, external hinges, and a central brass keyhole escutcheon on the upper case segment. The lower tier incorporates flush-fitted recessed brass side plates and carrying handles designed for shipboard stowage. Externally, the box measures 19 cm in height, 19 cm in width, and 17 cm in depth according to dealer physical specifications.
- Maker Attribution and Documentation Limits
- The seller attributes the chronometer to Asmus Johanneson of London, dating the instrument broadly to 1900–1920 or the 1900s. Johanneson is noted by the dealer as the head of a firm at 149 The Minories that supplied chronometers to the British Admiralty between 1890 and 1910. No internal movement photographs, escapement details, plate engravings, or instrument serial numbers are documented in the listing. Claims of internal mechanical completeness, full operational status, and specific Admiralty affiliation rely entirely on dealer statements and are not verified by photographic evidence.
Identification
- Reference
- 1618
- 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: Internal movement plates, balance assembly, escapement, and serial numbers are not pictured or specified
- Research required: Attribution to Asmus Johanneson, operational status, and date range rely on dealer claims