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The Encyclopedia of Horology

Pocket watch · Deck watch

Patek Philippe Ref. 738 Pocket Chronometer

Partially verified

This Patek Philippe Ref. 738 pocket chronometer, manufactured in 1921, is described as a "Deck-Watch" intended for scientific use. Housed in a 0.925 silver open-face case measuring 60 mm in diameter, the watch features a silver-colored dial with large Arabic numerals and blued steel spade hands. The movement is a rhodium-plated 19''' caliber, featuring a going barrel, straight-line lever escapement, and a bimetallic compensated Guillaume balance with gold poising screws. It is regulated by a polished steel index system with a swan-neck spring and micrometric screw. The movement was adjusted by H. Wehrli and bears the "Poinçon de Genève" hallmark twice. Documentation confirms the watch received a First Class Bulletin de marche with an honourable mention from the Astronomical Observatory of Geneva during the 1934 timing contest. Accessories include an Extract from the Archives and historical bulletins.

The Patek Philippe Ref. 738 pocket chronometer alongside its associated documentation.
The Patek Philippe Ref. 738 pocket chronometer alongside its associated documentation. — Antiquorum. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
catalog.antiquorum.swiss
Category
Pocket watch · Deck watch
Maker / attribution
Patek Philippe
Reference
738
Catalogue / lot identifier
476
Source-reported date
1921
Source-reported place
Switzerland
Source-reported serial
191 008

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

Case and Dial

The watch is presented in an open-face case constructed from 0.925 silver. It features a round profile designed for functional use as a deck watch. The exterior maintains a simple, utilitarian aesthetic consistent with its intended application for precision scientific observation and shipboard navigation.

The silver-colored dial displays large, suspended Arabic numerals. The time is indicated by blued steel spade hands, with a subsidiary seconds register positioned at the 6 o'clock mark. Both the dial and case exhibit minor signs of wear, including light scratches, as noted in the auction description.

Evidence for this section
  • “Very fine, silver (0.925), open-face, keyless-winding, round-shaped, pocket chronometer”
  • “Silver colour dial, with large suspended Arabic numerals; blued steel “Spade” hands.”

Movement and Escapement

The movement is a rhodium-plated 19''' caliber utilizing a going barrel and a straight-line lever escapement. Chronometric precision is facilitated by a bimetallic compensated Guillaume balance, which incorporates gold poising screws and a blued steel hairspring with a terminal curve.

Regulation is managed by a polished steel index system equipped with a swan-neck spring and a micrometric screw. The movement was adjusted by H. Wehrli of Geneva and displays the Poinçon de Genève hallmark in two locations, indicating its adherence to established quality standards at the time of assembly.

Evidence for this section
  • “19’’’ movement, rhodium-plated, going barrel, straight-line lever escapement, cut bimetallic compensated Guillaume balance”
  • “polished steel index-regulator with swan-neck spring and micrometric screw, adjusted by the precision timer “régleur” H. Wehrli, Geneva, “Poinçon de Genève” (Geneva Quality Hallmark or Geneva seal) stamped twice.”

Observatory Performance

In 1934, this specific chronometer participated in a timing contest at the Astronomical Observatory of Geneva. It achieved a First Class Bulletin de marche and an honourable mention, scoring 624 points out of a possible 1,000.

The watch was produced in 1921 and eventually sold on January 30, 1942, as verified by the Extract from the Archives provided with the object. Copies of the original observatory bulletins from 1932 to 1934 accompany the watch to document its historical performance record.

Evidence for this section
  • “At the timing contest organised in 1934 at the Astronomical Observatory of Geneva, this chronometer was awarded a First Class Bulletin , with Honourable mention.”
  • “The Extract from the Archives, dated November 8, 2017, mentioned that this watch was made in 1921 and sold on January 30, 1942.”

Open research questions

  • What is the significance of the specific ranking of 38th out of 40 in the 1934 contest relative to the watch's technical condition today?
  • Were there modifications made to the balance during the interval between manufacture in 1921 and the 1934 observatory testing?

Source evidence

Recorded claims and source quotations for Patek Philippe Ref. 738 Pocket Chronometer
FieldSource-reported valueSource quotation
MakerPatek Philippe“Patek Philippe, Geneva”
ModelDeck-Watch“so-called “Deck-Watch””
Reference738“Reference 738”
Case Material0.925 silver“Very fine, silver (0.925), open-face”
Date of Manufacture1921“made in 1921”
Movement Caliber19'''“19’’’ movement”
Balance TypeGuillaume balance“cut bimetallic compensated Guillaume balance”
CertificationFirst Class Bulletin de marche“awarded a First Class Bulletin , with Honourable mention”

Visible details

  • Silver-colored dial with subsidiary seconds at 6 o'clock
  • Blued steel spade hands
  • Movement bridge bears Patek Philippe & Co signature
  • Visible index regulator with swan-neck spring and micrometric screw

Research qualifications

  • Condition report notes slight scratches on the case and dial
  • Overhaul recommended by the auction description

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

Consulted source

Patek Philippe Ref. 738, pocket chronometer, so-called “Deck-Watch”, especially made for scientific purposes, Guillaume balance, Bulletin of the Astronomical Observatory of Geneva, Honourable mention; silver

Reviewed 2026-10-26 · Record 8ae286eb8d

Terms in this record

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

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