John Arnold & Son No. 326 Marine Chronometer
Record status
Individual type · partial
Period
circa 1788-1810
This one-day marine chronometer by John Arnold & Son originated as a pocket chronometer movement before being fitted into a gimballed three-tier mahogany box around 1810.
The full-plate gilt brass fusee movement features four pillars, Harrison's maintaining power, an Arnold-type spring detent escapement, and an Arnold OZ-type balance with bimetallic segments and a blued steel helical balance spring. The potence plate is engraved with the maker's signature along with serial and production numbers.
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
- Boxed marine chronometer
- Maker
- John Arnold & Son
- Balance
- Arnold OZ-type balance
- Dimensions
- 95 x 93 x 92 mm
- Escapement
- Arnold-type spring detent escapement
- Serial Number
- 326/627
- Place recorded
- United Kingdom
- Maker / attribution
- John Arnold & Son
Design
- Visible features
- • Gilt movement plate with engraved scrolling foliage on the balance cock • Engraved inscription reading 'John Arnold & Son London' and 'Inv.t et Fec.t' • Engraved serial marking 'No. 326 / 627' on the potence plate • Gimballed brass mounting ring set within a wooden casing corner • Blued steel balance spring and blued assembly screws visible on the potence plate
- Movement Construction
- The full-plate gilt brass movement features four pillars and a fusee with Harrison's maintaining power. The potence plate is engraved with the maker's signature and the serial number 'No. 326/627'. The fusee pipe remains angled on its upper rim, reflecting the geometry of its original pocket-watch casing. Modifications noted include a plugged hole where the maintaining power spring was previously situated and burrs found under the balance cock foot, which are interpreted as evidence of a new balance staff or repivoting.
- Conversion and Provenance
- The object originated as a pocket chronometer movement, which was later removed from its original metal casing and fitted into the current gimballed mahogany box around 1810. The box is constructed of mahogany with dovetailed corners and includes ink markings, including one referencing the Reverend G. Fisher. Internal evidence of the object's history includes a brass poising weight within the gimbal bowl, behind which is trapped a piece of paper marked with the date 'July 22nd 1836', which overwrites a faded inscription containing '1825'.
- Escapement and Balance Assembly
- The chronometer uses an Arnold-type spring detent escapement. The Arnold OZ-type balance consists of a three-arm steel central wheel and bimetal rim segments made of blued steel and 'Platina' metal. The system includes a blued steel helical balance spring. Technical anomalies on the potence plate include two small unthreaded holes adjacent to the centre pivot, a drilled dot within a patch of dull gilding, and a small hole in the edge of the three-arm steel wheel, all of which have unknown functions.
Identification
- Reference
- ZAA0067
- Serial number
- 326/627
- 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: The dial and external box exterior are not visible in the provided photo, which shows only the movement in the gimbal bowl.
- Research required: Source notes the chronometer was converted from a pocket chronometer to a boxed marine chronometer circa 1810.