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The Encyclopedia of Horology

Marine chronometer · One-day marine chronometer

Thomas Earnshaw No. 365/2536 One-Day Marine Chronometer

Partially verified

This one-day marine chronometer by Thomas Earnshaw features a 3-inch silvered dial with Roman numerals, subsidiary seconds, plain blued steel hands, and signatures reading 'Thos. Earnshaw, INVT ET FECIT, No 365, ONE DAY'. The four-pillar movement is signed 'Thos. Earnshaw, Invt et fecit, No 365, London 2536' and incorporates an Earnshaw-type spring detent escapement, a bimetallic Z-balance with brass weights, and a helical spring. Housed in a brass bowl with a skirt counterweight, it is presented in an associated mahogany box.

Dial and brass bowl of the chronometer fitted in an opened mahogany box
Dial and brass bowl of the chronometer fitted in an opened mahogany box — Woolley and Wallis. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.woolleyandwallis.co.uk
Category
Marine chronometer · One-day marine chronometer
Maker / attribution
Thomas Earnshaw
Reference
Not recorded
Catalogue / lot identifier
760
Source-reported date
circa 1805
Country
United Kingdom
Source-reported serial
365/2536

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 and Exterior Observations

The chronometer features a 3-inch silvered dial with black Roman numerals and an outer minute track. A subsidiary seconds dial is positioned above the 6 o'clock mark, accompanied by plain blued steel hands.

The dial is signed 'Thos. Earnshaw, INVT ET FECIT, No 365, ONE DAY'. The movement is contained within a brass bowl featuring a skirt counterweight.

Evidence for this section
  • “the 3 inch silvered dial signed Thos. Earnshaw, INVT ET FECIT, No 365, ONE DAY”
  • “subsidiary seconds, plain blued steel hands, Roman numerals”
  • “in typical Earnshaw brass bowl with skirt counterweight”

Movement Construction

The four-pillar movement bears the signature 'Thos. Earnshaw, Invt et fecit, No 365, London 2536'.

The mechanism utilizes an Earnshaw-type spring detent escapement, a bimetallic Z-balance with brass compensation weights, and a blued steel helical spring.

Evidence for this section
  • “the 4 pillar movement signed Thos. Earnshaw, Invt et fecit, No 365, London 2536”
  • “Earnshaw type escapement with spring detent, bimetallic Z balance with brass compensation weights”
  • “blued steel helical spring”

Case and Associated Components

The device is presented in a later associated mahogany box measuring 5 inches (12cm) square. The box features an aged paper label inside the upper lid and a re-engraved ivory plaque reading 'Earnshaw 365 Deckwatch'.

The original gimbal and brass locking arms are noted as lacking.

Evidence for this section
  • “(gimbal and brass locking arms lacking)”
  • “in a later associated mahogany box with re-engraved ivory plaque Earnshaw 365 Deckwatch”
  • “box 5in. (12cm) square”

Open research questions

  • What is the significance of the dual numbering (365 and 2536) in the context of Earnshaw’s numbering system?
  • Does the re-engraved ivory plaque 'Earnshaw 365 Deckwatch' suggest a prior misidentification of the object's function in the secondary market?
  • Is there evidence to confirm if the movement (2536) was originally paired with the dial (365) or if this represents a historical marriage of parts?

Source evidence

Recorded claims and source quotations for Thomas Earnshaw No. 365/2536 One-Day Marine Chronometer
FieldSource-reported valueSource quotation
Dial SignatureThos. Earnshaw, INVT ET FECIT, No 365, ONE DAY“signed Thos. Earnshaw, INVT ET FECIT, No 365, ONE DAY”
Movement SignatureThos. Earnshaw, Invt et fecit, No 365, London 2536“signed Thos. Earnshaw, Invt et fecit, No 365, London 2536”
Escapement and BalanceEarnshaw type spring detent escapement with bimetallic Z balance“Earnshaw type escapement with spring detent, bimetallic Z balance with brass compensation weights”
Box Dimensions5 inches (12 cm) square“box 5in. (12cm) square”
Approximate Datingcirca 1805“circa 1805”

Visible details

  • Silvered dial with black Roman hour numerals and an outer minute track
  • Large subsidiary seconds dial positioned above the 6 o'clock mark
  • Open wooden box displaying an aged paper label attached inside the upper lid
  • Brass chronometer bowl seated within the wooden case opening

Research qualifications

  • Source notes that the gimbal and brass locking arms are lacking
  • Housed in a later associated mahogany box with a re-engraved plaque

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

Consulted source

Thomas earnshaw no.365/2536. a one day marine chronometer | Woolley and Wallis

Reviewed 2026-10-22 · Record 7758fb0f17

Terms in this record

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

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