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The Encyclopedia of Horology

Marine chronometer · Two-day marine chronometer

A. Johannsen & Co. Two-Day Marine Chronometer No. 8644

Partially verified

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.

A. Johannsen & Co. two-day marine chronometer in an open mahogany box with brass gimbal
A. Johannsen & Co. two-day marine chronometer in an open mahogany box with brass gimbal — Woolley and Wallis. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.woolleyandwallis.co.uk
Category
Marine chronometer · Two-day marine chronometer
Maker / attribution
A. Johannsen & Co.
Reference
Not recorded
Catalogue / lot identifier
194
Source-reported date
late 19th century
Country
United Kingdom
Source-reported serial
8644

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

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.

Evidence for this section
  • “signed 'A. Johannsen & Co., MAKERS TO THE ADMIRALTY, THE INDIAN GOVT & ROYAL NAVIES OF ITALY, SPAIN & PORTUGAL, 149 Minories, London' and numbered '8644'”
  • “the circular 4in silvered dial, with subsidiary seconds and up/down dials and Roman and Arabic numerals”

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.

Evidence for this section
  • “mounted on a brass gimbal”
  • “the case lacking its upper section”
  • “with a later ivorine plaque”

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.

Evidence for this section
  • “the circular single fusee movement with four pillars and Harrisons maintaining power”
  • “with an Earnshaw type spring detent escapement and split bi-metallic balance and helical balance spring”
  • “with an engine turned backplate”

Open research questions

  • Does the later ivorine plaque contain specific serial or inventory identifiers that could verify the 1944-1971 Admiralty records?
  • Are there any visible marks on the mahogany case that indicate the original structure of the missing upper section?
  • Is the movement's engine-turned pattern consistent with other known Johannsen chronometers of the late 19th century?

Source evidence

Recorded claims and source quotations for A. Johannsen & Co. Two-Day Marine Chronometer No. 8644
FieldSource-reported valueSource quotation
Maker SignatureA. Johannsen & Co., MAKERS TO THE ADMIRALTY, THE INDIAN GOVT & ROYAL NAVIES OF ITALY, SPAIN & PORTUGAL, 149 Minories, London“signed 'A. Johannsen & Co., MAKERS TO THE ADMIRALTY, THE INDIAN GOVT & ROYAL NAVIES OF ITALY, SPAIN & PORTUGAL, 149 Minories, London'”
Movement DetailsSingle fusee with four pillars, Harrison's maintaining power, Earnshaw-type spring detent escapement, split bi-metallic balance, and helical balance spring“the circular single fusee movement with four pillars and Harrisons maintaining power, with an Earnshaw type spring detent escapement and split bi-metallic balance and helical balance spring”
Dial Size4 inches“the circular 4in silvered dial”
Case Dimensions16.8 cm high, 18.5 cm wide“16.8cm high, 18.5cm wide”
Case ConditionLacking upper section“the case lacking its upper section”
DatingLate 19th century“A late 19th century mahogany cased two day marine chronometer”
DocumentationFacsimile Admiralty record sheet 1944-1971“accompanying facsimile of its Admiralty record sheet from 1944 to 1971”

Visible details

  • 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.

Research qualifications

  • Source reports the mahogany case lacks its upper section.
  • Internal movement features are source-reported and not visible in the photograph.

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

Consulted source

A late 19th century mahogany cased two day marine chronometer by a. johannsen & co. | Woolley and Wallis

Reviewed 2026-10-22 · Record b0960257ae

Terms in this record

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

Other two-day marine chronometer records