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The Encyclopedia of Horology

Pocket watch · Split-seconds chronograph pocket watch

Dent, London Yellow Gold Open-Faced Keyless Split-Seconds Chronograph Pocket Watch, No. 26507

Partially verified

This open-faced keyless split-seconds chronograph pocket watch, numbered 26507, dates to 1870–71 and is signed by Dent, London. The 18k yellow gold case measures 49 mm in diameter and carries London hallmarks for 1870 with maker's initials AN for Adolph Nicole, featuring a pin for hand setting and a crown locking slide on the band. The source reports a gilt three-quarter plate lever escapement movement with Nicole Nielsen winding and bi-metallic compensation balance. The eccentric white enamel dial features black Roman numerals and blued steel hands, housing a single-button split-seconds chronograph mechanism without reset operated through the crown.

Front view of Dent, London yellow gold open-faced keyless split-seconds chronograph pocket watch No. 26507
Front view of Dent, London yellow gold open-faced keyless split-seconds chronograph pocket watch No. 26507 — Sotheby's. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.sothebys.com
Category
Pocket watch · Split-seconds chronograph pocket watch
Maker / attribution
Dent, London
Reference
Not recorded
Catalogue / lot identifier
428
Source-reported date
1870-71
Country
United Kingdom
Source-reported serial
26507

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 Configuration and Visual Characteristics

The pocket watch presents an open-faced configuration featuring an eccentric white enamel dial. The primary timekeeping chapter ring, formed of black Roman numerals, is visibly shifted downwards relative to the dial center. Time is indicated by blued steel spade-tipped hour and minute hands, while two blued central seconds hands serve the chronograph complication.

According to cataloguing details, the dial is signed 'Dent, 33 Cockspur St., London, 26507'. Above the dial assembly, the yellow gold case is fitted with a fluted winding crown, accompanied by a crown bow showing a small stamped punch mark.

Evidence for this section
  • “Frontal view of an open-faced yellow gold pocket watch with an eccentric white enamel dial.”
  • “Black Roman numeral hour chapter ring offset downwards relative to the center.”
  • “Blued steel spade-tipped hour and minute hands accompanied by two central chronograph seconds hands.”
  • “Fluted winding crown with crown bow bearing a small stamped punch mark.”
  • “eccentric white enamel dial, Roman numerals, signed Dent, 33 Cockspur St., London, 26507”

Case Construction and Hallmarking

The 18k yellow gold case measures 49 mm in diameter and includes functional exterior controls consisting of a pin for hand setting and a crown locking slide positioned along the band.

The auction entry records that the case is numbered 26507, stamped with casemaker's initials 'AN' attributed to Adolph Nicole, and bears London hallmarks corresponding to 1870. The case back exterior and inner hallmarks cannot be evaluated from the single frontal image provided.

Evidence for this section
  • “18k yellow gold, pin for hand setting, crown locking slide on the band, case stamped with London hallmarks for 1870, casemaker's initials AN for Adolph Nicole, and numbered 26507”
  • “Diameter: 49 mm”

Reported Movement and Chronograph Operation

The movement is not exposed in the visual documentation, but the source describes it as a gilt three-quarter plate lever escapement movement with Nicole Nielsen keyless winding and a bi-metallic compensation balance. The backplate is catalogued as signed 'Dent, Watchmaker to the Queen, 33, Cockspur Street, London, Patent, No. 26507'.

Functionally, the mechanism is described as an unusual single-button split-seconds chronograph operated through the crown without a standard zero-reset. The source specifies a three-stage sequence: an initial crown depression splits the hands and stops the lower hand while the upper hand continues running; a second depression stops the second hand; and a third depression causes both hands to rejoin and resume running simultaneously.

Evidence for this section
  • “Nicole Nielsen winding, lever escapement, gilt three-quarter plate movement, bi-metallic compensation balance, the backplate signed Dent, Watchmaker to the Queen, 33, Cockspur Street, London, Patent, No. 26507”
  • “This unusual split-seconds chronograph is activated via the crown. The action is as follows: first depression splits the hands and stops the lower chronograph hand; the upper chronograph seconds hand continues to run second depression stops the second chronograph hand third depression rejoins the two chronograph hands and they simultaneously start running again”

Open research questions

  • What specific hallmark symbols are present inside the case back to confirm the 1870 London date letter and gold standard?
  • Does the movement plate display Nicole's patent numbers or additional stamps alongside the Dent Cockspur Street signature?
  • What is the condition of the chronograph wheelwork and castle-wheel mechanism responsible for the continuous-run split sequence?

Source evidence

Recorded claims and source quotations for Dent, London Yellow Gold Open-Faced Keyless Split-Seconds Chronograph Pocket Watch, No. 26507
FieldSource-reported valueSource quotation
MovementNicole Nielsen winding, lever escapement, gilt three-quarter plate movement, bi-metallic compensation balance“Nicole Nielsen winding, lever escapement, gilt three-quarter plate movement, bi-metallic compensation balance”
DialEccentric white enamel dial with Roman numerals“eccentric white enamel dial, Roman numerals, signed Dent, 33 Cockspur St., London, 26507”
Case18k yellow gold with London hallmarks for 1870 and casemaker's initials AN for Adolph Nicole“18k yellow gold, pin for hand setting, crown locking slide on the band, case stamped with London hallmarks for 1870, casemaker's initials AN for Adolph Nicole, and numbered 26507”
Diameter49 mm“Diameter: 49 mm”
FunctionSingle-button split-seconds chronograph watch without reset“single button split-seconds chronograph watch without reset”
Backplate InscriptionDent, Watchmaker to the Queen, 33, Cockspur Street, London, Patent, No. 26507“the backplate signed Dent, Watchmaker to the Queen, 33, Cockspur Street, London, Patent, No. 26507”
Casemaker MarkAN for Adolph Nicole“casemaker's initials AN for Adolph Nicole”

Visible details

  • Frontal view of an open-faced yellow gold pocket watch with an eccentric white enamel dial.
  • Black Roman numeral hour chapter ring offset downwards relative to the center.
  • Blued steel spade-tipped hour and minute hands accompanied by two central chronograph seconds hands.
  • Fluted winding crown with crown bow bearing a small stamped punch mark.

Research qualifications

  • Internal movement, caseback exterior, and inner hallmark stamps are not visible in the supplied single frontal photograph; mechanism details are source-reported.

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

Consulted source

Dent, London | A rare yellow gold open-faced keyless single button

Reviewed 2026-10-21 · Record adbf5f9ed0

Terms in this record

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

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