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The Encyclopedia of Horology

Marine chronometer · Box marine chronometer

Hamilton Model 21 Marine Chronometer

Partially verified

The source reports that this Hamilton Model 21 marine chronometer dates to circa 1940 and was made for the U.S. Army by Hamilton in Lancaster, Pennsylvania. According to the seller, the instrument features a 14-jewel chain fusee movement with a chronometer detent escapement, a poised balance wheel, and a 56-hour power reserve. It has an engraved silvered dial with Arabic numerals, a subsidiary seconds dial, and an up-down winding indicator. The chronometer is mounted in a brass gimbal ring within a brass-bound mahogany box and is accompanied by its winding key and paper starting instructions attached inside the upper lid.

Hamilton Model 21 marine chronometer in its brass-bound mahogany gimbaled box with winding key and lid instructions
Hamilton Model 21 marine chronometer in its brass-bound mahogany gimbaled box with winding key and lid instructions — Renaissance Antiques. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.renaissanceantiques.com
Category
Marine chronometer · Box marine chronometer
Maker / attribution
Hamilton
Reference
Model 21
Catalogue / lot identifier
LPEC 117
Source-reported date
Circa 1940
Country
United States

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

Historical Context and Origin

This Hamilton Model 21 marine chronometer is described as dating to circa 1940. The piece is attributed to the U.S. Army, with dial markings noting 'Property U.S. Army.'

The source states that Hamilton was one of the companies enlisted by the U.S. military to produce chronometers in anticipation of World War II.

Evidence for this section
  • “Circa 1940”
  • “This chronometer has its origins with the U.S. Army.”
  • “Hamilton was one of the American watch companies enlisted by the U.S. military to produce chronometers in anticipation of WWII.”

Dial and Exterior Observations

The chronometer is mounted in a mahogany box featuring a gimbal mechanism and brass corner brackets. An internal label on the lid is titled 'STARTING INSTRUCTIONS FOR HAMILTON SIZE 85 CHRONOMETERS.' A brass winding key is held in a cylindrical casing holder.

The silvered dial displays Arabic numerals, blued hands, a subsidiary seconds dial, and an up-down indicator. The dial is signed 'HAMILTON, LANCASTER, PA., U.S.A.' and 'PROPERTY U.S. ARMY.'

Evidence for this section
  • “Mahogany box fitted with flush brass corner brackets, latch hardware, and lid stay”
  • “Inner lid houses a printed paper label titled 'STARTING INSTRUCTIONS FOR HAMILTON SIZE 85 CHRONOMETERS'”
  • “Additionally the dial bears the signature “Hamilton, Lancaster, PA., USA; Property U.S. Army.””

Technical Specifications

The instrument is reported to feature a 14-jewel chain fusee movement with a chronometer detent escapement. It includes a poised balance wheel and a 56-hour power reserve.

A service label on the inner rim of the gimbaled bowl is marked '10422 Overhaul Due JUN 85'. The movement has not been uncased for verification in the provided source material.

Evidence for this section
  • “This Hamilton chronometer has a 14 jewel chain fusee driven movement with chronometer detent escapement.”
  • “It also features a poised balance wheel and maintains a 56 hour power reserve.”
  • “Gimbaled brass bowl features a service label along the inner rim reading '10422 Overhaul Due JUN 85'”

Open research questions

  • Does the 'Size 85' instruction label imply a specific production batch or variant within the Model 21 series?
  • Can the '10422' mark be linked to official military or civilian maintenance records?
  • What is the significance of the discrepancy between the dimensions listed in the product details and the dimensions listed in the summary section of the source?

Source evidence

Recorded claims and source quotations for Hamilton Model 21 Marine Chronometer
FieldSource-reported valueSource quotation
Maker and Location SignatureHamilton, Lancaster, PA., USA; Property U.S. Army“Additionally the dial bears the signature “Hamilton, Lancaster, PA., USA; Property U.S. Army.””
Movement Mechanism14 jewel chain fusee driven movement with chronometer detent escapement“This Hamilton chronometer has a 14 jewel chain fusee driven movement with chronometer detent escapement.”
Power Reserve56 hour“maintains a 56 hour power reserve.”
Dial FeaturesEngraved silvered dial with Arabic numerals, seconds dial, and winding status indicator“It has an engraved silvered dial with Arabic numerals, seconds dial, and winding status indicator.”
CasingGimbaled mahogany case with winding key“The chronometer comes in a gimbaled mahogany case with winding key”
Dimensions7 1/2 inches High x 7 3/4 inches Wide x 7 3/4 inches Deep“7 1/2″ High x 7 3/4″ Wide x 7 3/4″ Deep”

Visible details

  • Mahogany box fitted with flush brass corner brackets, latch hardware, and lid stay
  • Inner lid houses a printed paper label titled 'STARTING INSTRUCTIONS FOR HAMILTON SIZE 85 CHRONOMETERS'
  • Movement bowl mounted on a brass gimbal ring with lock mechanism
  • Gimbaled brass bowl features a service label along the inner rim reading '10422 Overhaul Due JUN 85'
  • Silvered dial with black Arabic numerals, blued hands, subsidiary seconds, and an up-down indicator below 12 o'clock
  • Dial inscription partially visible including 'HAMILTON, LANCASTER, PA., U.S.A.' and 'PROPERTY U.S. ARMY'
  • Brass winding key seated in a cylindrical holder in the right corner of the casing

Research qualifications

  • Movement is not directly photographed uncased; technical details are source-reported
  • Specific chronometer movement serial number is not provided in the text or clearly legible on the dial face

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

Consulted source

American Hamilton Model 21 Marine Chronometer - Renaissance Antiques

Reviewed 2026-10-25 · Record a4e66e8ac1

Terms in this record

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

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