Joseph Banister Marine Chronometer 'Patent No. 1'
Record status
Individual type · partial
Period
1830-1840
Source cataloguers describe this marine chronometer as produced by Joseph Banister of Colchester between 1830 and 1840. Contained within a standard brass drum with a leather travelling box, the movement features an experimental constant-force escapement where a spiral spring impulses the balance roller through a three-armed pivoted lever.
The silvered brass dial is engraved and filled with black wax, displaying Roman numerals, subsidiary seconds, and an up-and-down reserve dial marked to 48 hours. The movement bears ebauche stamp 'J.M.' alongside internal numbers 5000 and 500, a fusee with maintaining power, and a bimetallic balance with a helical spring.
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 with constant-force escapement
- Ebauche mark
- J.M.
- Museum number
- 1958,1006.1949
- Place recorded
- United Kingdom
- Escapement type
- Constant-force escapement
- Movement number
- 5000
- Dial inscription
- Banister Colchester. Patent No. 1
- Production place
- Colchester
- Maker / attribution
- Joseph Banister
Design
- Visible features
- • Silvered dial with engraved Roman hour numerals and outer closed minute track • Upper subsidiary dial for state of winding marked WIND 48 to UP 0 • Lower subsidiary dial for running seconds with Arabic numerals at ten-second intervals • Engraved signature across the dial centre reads 'Banister, Colchester. PATENT. No 1' • Dial plate secured by two countersunk screws visible near the III and IX hour numerals
- Attribution and Context
- The chronometer is dated by the source to 1830–1840. Joseph Banister (1778–1875) obtained patent No. 7083 on 7 May 1836, which covered a gravity escapement for a precision regulator and improvements applicable to watches and chronometers. The source notes that while it is assumed this chronometer represents the improvement mentioned in the patent, it is not clear what the specific improvement referred to in the patent actually is.
- Movement and Escapement
- The movement features a full-plate construction with hand-spotted plates and a fusee with maintaining power. Ebauche marks 'J.M.' are punched on the dial side of the front plate. The movement is numbered '5000' under the maintaining detent and '500' on the inside of the front plate. The constant-force escapement utilizes a three-armed pivoted lever to impulse the balance via a spiral spring. The system is designed for one-way impulse and incorporates a jewelled discharge roller. Observers note that the escapement components, particularly the two-part balance cock, exhibit comparatively crude workmanship, suggesting that a standard chronometer movement was modified and fitted with these parts by Joseph Banister.
- Dial and Exterior Construction
- The object features a silvered brass dial with engraved Roman numerals and an outer minute track, filled with black wax. It includes an upper subsidiary dial for the winding reserve and a lower subsidiary dial for running seconds. The hands are gold for the hours and minutes, and blued steel for the subsidiary indications. The movement is housed in a brass drum with a threaded bezel and a flat glass. The drum displays filled-in holes previously used for gimbal mounting and a spring-loaded escutcheon plate in the base. The dial is held by two countersunk screws and a positioning peg, and is signed: 'Banister Colchester. Patent No. 1'.
Identification
- Reference
- Patent No. 1
- Serial number
- 5000
- 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 leather travelling box, brass drum case, and key described by the source are not shown in this dial photograph
- Research required: Movement details and constant-force escapement mechanisms are concealed behind the dial