Thomas Mudge Marine Timekeeper No. 1
Record status
Individual type · partial
Period
1771-1774
Thomas Mudge created this eight-day marine timekeeper between 1771 and 1774, known as his Marine Timekeeper No. 1. According to the British Museum, it was constructed in Plymouth though inscribed London on the back plate.
The movement is powered by two separate mainsprings housed in a single barrel driving a fusee fitted with Harrison's maintaining power. It features Mudge's constant-force escapement and thermal compensation utilizing two bimetallic strips. The gilded brass dial plate contains three white enamel subsidiary dials calibrated in time and degrees, alongside an arc-shaped up-and-down indicator calibrated from 1 to 7 days. The timekeeper is housed within an octagonal glazed mahogany inner case.
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
- Eight-day marine chronometer
- Maker
- Thomas Mudge
- Signature
- Thos Mudge Invt et fect London
- Escapement
- Mudge's constant force escapement
- Museum Number
- 1958,1006.2119
- Place recorded
- United Kingdom
- Movement Duration
- Eight-day movement
- Maker / attribution
- Thomas Mudge
- Mainspring Configuration
- Two separate mainsprings housed in single barrel
Design
- Visible features
- • Octagonal mahogany case with rectangular glazed viewing windows set into each facet. • Gilded dial plate displaying three white enamel subsidiary circular dials and an arc-shaped up-and-down indicator sector. • Blued steel hands on the circular sub-dials and reserve indicator. • Pillar and gear train components visible through the side glass apertures.
- Dial and Indication
- The gilded-brass dial plate hosts three subsidiary white enamel dials displaying hours, minutes, and seconds. The dials are calibrated in time units and degrees, intended for longitudinal calculations. An arc-shaped indicator sector at the top, numbered 1-7 and flanked by 'U' and 'D', displays the state of winding. The hands are fashioned from blued steel, and the assembly is secured by silver scrolled spandrels.
- Mechanism and Escapement
- The movement features a single-barrel configuration containing two separate mainsprings driving a fusee with Harrison's maintaining power. The constant-force escapement incorporates two spiral springs and pivoted pallet arms, isolating the balance from the going train. Thermal compensation is achieved via two bimetallic strips. The balance staff pivots on a diamond endstone and is supported by four anti-friction rollers, though inspection indicates prior mechanical issues, including a nicked roller, pallet score marks, and balance pivot wear.
- Case and Exterior Construction
- The timepiece is housed in an octagonal inner mahogany box, described by the maker as wood instead of brass for economic reasons. The inner box features glazed panels in each facet and is reinforced by internal brass rings; it is designed to be dust-tight with overlapped joints. A separate mahogany outer carrying box exists, which contains padded side panels lined with faded red velvet. The inner box utilizes a seven-knuckle hinge, a push-piece catch, and a pierced bottom that allows access to the winding mechanism via an escutcheon plate.
Identification
- Reference
- 1958,1006.2119
- 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 outer octagonal carrying box described in the source is not shown in this photograph.
- Research required: The source notes production was claimed to be London on the signature plate but made in Plymouth.