Charles Frodsham Box Chronometer

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This instrument is a specialized timekeeper designed for finding longitude at sea. Its form is that of the standardized 19th-century marine chronometer. It was transferred to the Smithsonian from the U.S. Navy’s Bureau of Ships. The chronometer’s finisher, the firm of Charles Frodsham, traded in high-quality chronometers, clocks and watches. Frodsham (1810-71), was the son of William James Frodsham, co-founder of Parkinson & Frodsham. The younger Frodsham’s firm underwent many name and address changes, but continued in business from roughly 1837 until it became a subsidiary of Devon Instruments in 1977.
Mechanism details:
Escapement: Earnshaw, spring detent
Duration: 56-hour
Power source: Spring drive with chain and fusee
Balance spring: helical, blued steel
Key missing
Bowl details:
Brass bowl, fitted with a sprung cylindrical inner bowl as a dust cover (original work)
Brass fittings for gimbal, gimbal missing
Bezel screwed and milled
Crystal flat, small unpolished chamfer
Dial details:
Engraved and silvered brass
Indicates hours, minutes, seconds, winding level up and down
Hands: blued steel, fleur-de-lys
Inscription: "CHARLES FRODSHAM / 7 Pavement Finsbury Squr, / London No.1909”
1. Gould, Rupert T. The Marine Chronometer. London: Holland Press, 1960.
2. Mercer, Tony. Chronometer Makers of the World. Essex: NAG Press, 1991.
3. Mercer, R. Vaudry. The Frodshams. The Story of a Family of Chronometer Makers. London: Antiquarian Horological Society monograph 21, 1981.
4. Whitney, Marvin E. The Ship's Chronometer. Cincinnati: American Watchmakers Institute Press, 1985.
date made
Charles Frodsham
place made
United Kingdom: England, London
Physical Description
brass (overall material)
glass (overall material)
steel (overall material)
bezel - from catalog card: 4 3/16 in; 10.668 cm
backplate - from catalog card: 2 3/16 in; 5.588 cm
overall: 2 3/4 in x 4 1/4 in; 6.985 cm x 10.795 cm
ID Number
catalog number
accession number
Credit Line
Department of the Navy. Bureau of Ships
See more items in
Work and Industry: Mechanisms
Measuring & Mapping
Time and Navigation
Time and Navigation, National Air and Space Museum
Data Source
National Museum of American History


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