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The Encyclopedia of Horology

Marine chronometer · Two-day marine chronometer

Thomas Mercer Two-Day Marine Chronometer No. 18051

Partially verified

This two-day marine chronometer by Thomas Mercer Ltd, St. Albans, England, features a silvered dial mounted in a brass gimbal and bowl assembly within a stained walnut box. The dial is engraved with Roman numerals, an outer minute track, a 56-hour state-of-wind indicator below the XII numeral, and a subsidiary seconds register enclosing serial number 18051 at the VI numeral. Blued steel hands indicate the time. The auction catalogue notes that the stained walnut outer box cover is inlaid in marine ivory with the depiction of a whale.

Dial and gimbal assembly of Thomas Mercer two-day marine chronometer no. 18051
Dial and gimbal assembly of Thomas Mercer two-day marine chronometer no. 18051 — Nesbits Auctions Ltd. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.the-saleroom.com
Category
Marine chronometer · Two-day marine chronometer
Maker / attribution
Thomas Mercer Ltd
Reference
Not recorded
Catalogue / lot identifier
358
Source-reported date
Not established
Country
United Kingdom
Source-reported serial
18051

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

Dial Inscriptions and Subsidiary Registers

The timepiece features a silvered dial bearing Roman hour numerals and two distinct subsidiary registers. Across the centre, the dial is signed 'THOMAS MERCER LTD / ST. ALBANS, ENGLAND.', identifying the maker and origin.

A state-of-wind indicator is located directly below the XII numeral, calibrated from 0 to 56 hours and marked 'DOWN' and 'UP'. Above the VI numeral sits the subsidiary seconds register, graduated in ten-second increments and engraved with the serial number 18051.

Evidence for this section
  • “Silvered dial signed 'THOMAS MERCER LTD / ST. ALBANS, ENGLAND.' across the centre.”
  • “State-of-wind dial positioned below XII calibrated from 0 to 56 hours and marked 'DOWN' and 'UP'.”
  • “Subsidiary seconds dial above VI marked with ten-second increments and engraved with serial number 18051.”

Gimbal Assembly and Box Mountings

Direct visual inspection reveals the cylindrical chronometer bowl fashioned in brass and held within an outer brass gimbal ring. A dedicated locking arm for stabilizing the assembly is visible at the lower right of the mounting.

The gimballed chronometer sits within a stained wooden box, showing brass fittings at the visible corners. The saleroom description specifically lists the case as a 'stained walnut box, the cover inlaid in marine ivory with a whale'.

Evidence for this section
  • “Brass chronometer bowl mounted in a brass gimbal ring with a locking arm visible at lower right.”
  • “Housed in a stained wooden chronometer box with brass corner fittings visible.”
  • “in stained walnut box, the cover inlaid in marine ivory with a whale”

Source Evidence and Mechanism Limitations

The catalogue defines the object as 'A Two-Day Marine Chronometer by Thomas Mercer, St. Albans, England', supported by the 56-hour winding scale on the dial face. However, no internal images or technical descriptions of the movement, escapement, or balance assembly are provided in the source documentation.

Furthermore, while the auction entry records that the box cover features a whale inlaid in marine ivory, this ornamentation cannot be verified from the single dial view provided, remaining strictly a seller-reported attribute.

Evidence for this section
  • “A Two-Day Marine Chronometer by Thomas Mercer, St. Albans, England”
  • “the silvered dial with Roman numerals, subsidiary dials and numbered 18051”

Open research questions

  • What specific escapement configuration, balance type, and internal markings are present on the unexamined movement?
  • What is the physical appearance, execution, and composition of the whale inlay reported on the exterior cover of the walnut box?

Source evidence

Recorded claims and source quotations for Thomas Mercer Two-Day Marine Chronometer No. 18051
FieldSource-reported valueSource quotation
Maker and OriginThomas Mercer, St. Albans, England“A Two-Day Marine Chronometer by Thomas Mercer, St. Albans, England”
Dial Features and Serial NumberSilvered dial with Roman numerals and subsidiary dials, numbered 18051“the silvered dial with Roman numerals, subsidiary dials and numbered 18051”
Box DescriptionStained walnut box with marine ivory whale inlay“in stained walnut box, the cover inlaid in marine ivory with a whale”
Auction LotLot 358“Lot 358 A Two-Day Marine Chronometer by Thomas Mercer, St. Albans, England”
Auction Sale Date13 Nov 2019“Sale Date(s) 13 Nov 2019 10:30 GMT”

Visible details

  • Silvered dial signed 'THOMAS MERCER LTD / ST. ALBANS, ENGLAND.' across the centre.
  • State-of-wind dial positioned below XII calibrated from 0 to 56 hours and marked 'DOWN' and 'UP'.
  • Subsidiary seconds dial above VI marked with ten-second increments and engraved with serial number 18051.
  • Brass chronometer bowl mounted in a brass gimbal ring with a locking arm visible at lower right.
  • Housed in a stained wooden chronometer box with brass corner fittings visible.

Research qualifications

  • The external whale inlay described in the catalogue text is not visible in the presented dial view.
  • Movement escapement and balance details are unexamined and not illustrated.

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

Consulted source

A Two-Day Marine Chronometer by Thomas Mercer, St. Albans, England, the silvered dial with Roman

Reviewed 2026-10-21 · Record 36b41be244

Terms in this record

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

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