Skip to content
The Encyclopedia of Horology

Pocket watches · Escapement

Pocket Chronometers

Verified

High-precision pocket watches fitted with a detent (chronometer) escapement, built to marine or observatory rating standards.

Mechanism

The balance unlocks the escape wheel once per revolution via a spring detent, receiving a single clean impulse and remaining otherwise entirely free of the train, maximising isochronism at the cost of shock resistance.

Typical characteristics

  • Spring or pivoted detent escapement
  • Helical or spiral hairspring with compensation balance
  • Often boxed with a gimbal mount for marine use

Identification characteristics

  • Detent and impulse roller visible on the balance side of the movement
  • Certificates or engraved observatory trial results on high-grade examples

Collector significance

The precision benchmark against which lever watches were long measured, and essential to the history of marine navigation.

Known variations

  • Spring detent (pocket) chronometer
  • Pivoted detent chronometer
  • Deck watch

Photographs

British Museum Marine Chronometer
British Museum Marine Chronometer — Unattributed Wikimedia Commons contributor, CC0. Wikimedia Commons file page
A Pocket Chronometer’s Clues About Steel Use In Watchmaking | by ...
A Pocket Chronometer’s Clues About Steel Use In Watchmaking | by ... — medium.com, Rights unverified — web image search result, review pending. Web page (medium.com)
Pocket chronometers with detent escapement
Pocket chronometers with detent escapement — horology.ru, Rights unverified — web image search result, review pending. Web page (horology.ru)
Three silver open faced pocket chronometers, Movements early 19th
Three silver open faced pocket chronometers, Movements early 19th — sothebys.com, Rights unverified — web image search result, review pending. Web page (sothebys.com)
IWC, pocket watch, 18k gold, chronometers, early 20th century. Clocks ...
IWC, pocket watch, 18k gold, chronometers, early 20th century. Clocks ... — auctionet.com, Rights unverified — web image search result, review pending. Web page (auctionet.com)
ETERNA, pocket watch, 14k gold, chronometers, 1920s/30s. Clocks ...
ETERNA, pocket watch, 14k gold, chronometers, 1920s/30s. Clocks ... — auctionet.com, Rights unverified — web image search result, review pending. Web page (auctionet.com)

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Gould, R. T., The Marine Chronometer: Its History and Development

Where sources disagree, the disagreement is stated rather than resolved silently.