Thomas Mercer Two-Day Marine Chronometer No. 19116
Record status
Individual type · partial
Period
2nd Quarter of 20th Century
This Thomas Mercer two-day marine chronometer is housed in a two-tier mahogany deck box. The instrument features a four-pillar single chain fusee movement with Harrison’s maintaining power and an Earnshaw-type spring detent escapement.
It includes a split bimetallic balance with cylindrical compensating weights and a helical palladium balance spring. The 4-inch circular silvered dial displays Roman numerals, a central subsidiary seconds dial, and a power reserve indicator marked UP/DOWN. Uniquely, the dial contains a side aperture exposing electrical contacts and terminals on the case side, configured to emit a one-second pulse. The chronometer is mounted in gimbals within a lacquered brass bowl with a shuttered winding aperture at the rear.
The mahogany box features a glazed viewing panel in the lid and an applied brass plate identifying the maker, location, and serial number.
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
- Maker
- Thomas Mercer
- Escapement
- Earnshaw-type spring detent
- Dial Features
- Power reserve and electrical contacts
- Movement Type
- Four-pillar single chain fusee
- Balance Spring
- Helical palladium
- Box Dimensions
- 17cm x 19cm
- Place recorded
- England
- Maker / attribution
- Thomas Mercer
Design
- Case and Housing
- The chronometer is enclosed in a lacquered brass bowl with a screw-down bezel. A shuttered aperture at the rear allows for winding. The instrument is suspended in gimbals. The entire assembly is housed in a two-tier mahogany deck box. The lid is fitted with a glazed viewing panel. A brass plate applied to the box identifies the manufacturer as Thomas Mercer Ltd of St. Albans, England, and repeats the serial number 19116.
- Visible features
- • The dial is engraved with the caution 'HANDS FORWARD ONLY'. • A subsidiary seconds dial at the centre is pierced to expose the seconds wheel. • Electrical terminals are visible on the side of the brass bowl. • The mahogany box includes a glazed lid section.
- Dial and Electrical Features
- The 4-inch silvered dial is engraved with Roman numerals and carries the maker's signature and serial number. It features a power reserve indicator at the top labeled UP/DOWN and a pierced subsidiary seconds dial. An aperture in the dial reveals electrical contacts which connect to external terminals. These contacts are designed to emit a one-second pulse. The dial also features an engraved caution reading 'HANDS FORWARD ONLY' around the circumference.
- Movement and Escapement Construction
- The movement is constructed as a four-pillar single chain fusee mechanism. It incorporates Harrison’s maintaining power to ensure continuous operation during winding. The escapement is of the Earnshaw-type spring detent variety. The regulation is controlled by a split bimetallic balance fitted with cylindrical compensating weights and a helical palladium balance spring. The backplate of the movement is spotted, and the pillars and backcock are secured with blued-steel screws.
Identification
- Serial number
- 19116
- 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 exact survey or astronomical purpose of the electrical pulse mechanism remains unconfirmed beyond the suggested likelihood.
- Research required: The functional status regarding accuracy is not verified by the auction description.