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The Encyclopedia of Horology

Pocket watch · Deck chronometer

Longines Observatory Calibre 26.99 deck chronometer

Partially verified

This large Swiss deck chronometer by Longines features caliber 26.99, an observatory-grade movement housed in a tiered base metal case fitted inside a wooden block. The white enamel dial displays stylized Arabic numerals, an outer railway minute track, and subsidiary seconds at 6 o'clock with blued steel hands. Fitted with movement number 2971458, the watch competed in the 1920 Neuchâtel Observatory chronometer competition and the 1930 Geneva Observatory trials under regulator David Perret of St-Imier, according to auction documentation. The movement is reported to include a lever escapement, Guillaume compensation balance, and blued Breguet balance spring.

Front view of the Longines deck chronometer mounted inside its fitted wooden case
Front view of the Longines deck chronometer mounted inside its fitted wooden case — Auktionen Dr. Crott. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.invaluable.com
Category
Pocket watch · Deck chronometer
Maker / attribution
Longines
Reference
Cal. 26.99
Catalogue / lot identifier
128
Source-reported date
circa 1913
Country
Switzerland
Source-reported serial
2971458

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

Object Identity and Provenance

This Longines deck chronometer is identified by movement number 2971458 and is dated to approximately 1913. The movement, caliber 26.99, was reserved exclusively for use in observatory competitions by the manufacturer's regulation department.

The movement has a recorded history of participation in institutional trials, specifically the 1920 Neuchâtel Observatory chronometer competition ('Chronomètres de Poche 1re Classe') and the 1930 Geneva Observatory competition. In both instances, the regulator was identified as David Perret of St-Imier.

Evidence for this section
  • “Movm. No. 2971458”
  • “Cal. 26.99”
  • “circa 1913”
  • “reserved exclusively for use in the observatory competitions”
  • “This Longines chronometer movement participated in the 1920 Neuchâtel Observatory chronometer competition "Chronomètres de Poche 1re Classe"”
  • “In 1930, it successfully participated in the Geneva Observatory competition.”
  • “The regulator in both cases was David Perret of St-Imier.”

Construction and Dial

The watch is housed in a tiered, base metal case with a glazed movement. It is fitted within a square-profile wooden block that is stamped with the number 2971458 on the lower right front. A fluted winding crown with an oval top bow protrudes from the wooden case.

The watch features a white enamel dial with stylized Arabic numerals and blued hands. A subsidiary seconds subdial is located at the 6 o'clock position.

Evidence for this section
  • “Case: Base metal, tiered, glazed movement.”
  • “Dial: Enamel.”
  • “Fitted in a square-profile wooden block stamped with 2971458 on the lower right front”
  • “Fluted winding crown with an oval top bow protruding from the wooden case”
  • “White enamel dial with stylized Breguet-style Arabic numerals and blued hands”
  • “Small seconds subdial located at the 6 o'clock position”

Technical Specifications

The movement is a bridge construction featuring a lever escapement, a Guillaume gold screw compensation balance, and a blued Breguet balance spring with two terminal curves by Phillips. The balance and mainspring barrel were enlarged to accommodate the movement's dimensions.

Regarding historical performance, the chronometer achieved a score of A=13.70 points in the 1920 Neuchâtel trials with a mean daily rate deviation of 0.17 seconds.

Evidence for this section
  • “Movm.: Bridge movement, lever escapement, Guillaume gold screw compensation balance, blued Breguet balance spring with 2 terminal curves by Phillips.”
  • “Because of the larger dimensions of the movement, both the Guillaume balance and the mainspring barrel were enlarged accordingly.”
  • “with a mean daily rate deviation of 0.17 seconds, achieved a score of A=13.70 points”

Open research questions

  • Verify if the physical extracts by Andreas Hidding and the Geneva Observatory register mentioned in the description are present with the lot, as they are described but not pictured.
  • Clarify the current condition of the movement, noted as 'capable of running, cleaning recommended'.

Source evidence

Recorded claims and source quotations for Longines Observatory Calibre 26.99 deck chronometer
FieldSource-reported valueSource quotation
Movement Number2971458“Movm. No. 2971458”
Calibre26.99“Cal. 26.99”
Dimensions68 mm“Dimensions 68 mm”
Weight241 g“Weight 241 g”
OriginSchweiz“Origin Schweiz”
RegulatorDavid Perret of St-Imier“The regulator in both cases was David Perret of St-Imier.”
Total Weight241 g“Weight 241 g”

Visible details

  • White enamel dial with stylized Breguet-style Arabic numerals and blued hands
  • Small seconds subdial located at the 6 o'clock position
  • Fitted in a square-profile wooden block stamped with 2971458 on the lower right front
  • Fluted winding crown with an oval top bow protruding from the wooden case

Research qualifications

  • Rear case and movement interior are not visible in the provided image
  • Extract documents mentioned in the description are not pictured

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

Consulted source

At Auction: Longines - Observatory Caliber

Reviewed 2026-10-25 · Record 054b20d6d1

Terms in this record

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