A. Johannsen & Co. Two-Day Marine Chronometer No. 8644
Record status
Individual type · partial
Period
late 19th century
Dating to the late 19th century, this two-day marine chronometer by A. Johannsen & Co. is housed in a brass gimbal within a mahogany box. According to the source, the four-inch circular silvered dial features Roman and Arabic numerals, subsidiary seconds, an up/down state-of-wind dial, and the maker's signature numbered 8644.
The source reports a circular single fusee movement with four pillars, Harrison's maintaining power, an Earnshaw-type spring detent escapement, a split bi-metallic balance, a helical balance spring, and an engine-turned backplate. The case lacks its original upper section and bears a later ivorine plaque.
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
- Two-day marine chronometer
- Dial Size
- 4 inches
- Case Condition
- Lacking upper section
- Place recorded
- United Kingdom
- Case Dimensions
- 16.8 cm high, 18.5 cm wide
- Maker Signature
- A. Johannsen & Co., MAKERS TO THE ADMIRALTY, THE INDIAN GOVT & ROYAL NAVIES OF ITALY, SPAIN & PORTUGAL, 149 Minories, London
- Movement Details
- Single fusee with four pillars, Harrison's maintaining power, Earnshaw-type spring detent escapement, split bi-metallic balance, and helical balance spring
- Maker / attribution
- A. Johannsen & Co.
Design
- Visible features
- • Chronometer bowl is mounted within a brass gimbal ring inside the mahogany case. • A winding key rests in a brass socket at the right corner inside the case. • The open viewing section has an aperture and carries an ivorine plaque on its upper rim. • Brass fittings, latching mechanisms, and a keyhole escutcheon are visible on the exterior of the box.
- Identity and Dial
- This marine chronometer is signed 'A. Johannsen & Co.' and identified by serial number 8644. The maker's signature specifies their role as suppliers to the Admiralty and several international navies, listing the firm's address at 149 Minories, London. The timepiece features a 4-inch silvered dial displaying both Roman and Arabic numerals. It includes subsidiary seconds and an up/down dial to indicate the remaining power reserve.
- Construction and Housing
- The chronometer bowl is held within a brass gimbal ring, housed in a mahogany case. External hardware includes brass fittings, latching mechanisms, and a keyhole escutcheon. The case is described as lacking its original upper section. It also carries a later ivorine plaque on the rim.
- Movement Technical Description
- The movement is a circular single fusee type constructed with four pillars. It utilizes Harrison's maintaining power. The escapement is an Earnshaw-type spring detent design, paired with a split bi-metallic balance and a helical balance spring. The movement backplate is reported to be engine-turned.
Identification
- Serial number
- 8644
- 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: Source reports the mahogany case lacks its upper section.
- Research required: Internal movement features are source-reported and not visible in the photograph.