Molyneux & Sons Box Chronometer
date: label: date made
content: 1835-1842
name: label: maker
content: Molyneaux & Sons
notes: label: Description
content: This instrument is a specialized timekeeper for finding longitude at sea. It was made by the firm Robert Molyneux & Sons of London, England, between 1832 and 1845. The U.S. Navy Bureau of Ships transferred it to the Smithsonian in 1953.
label: Description
content: To find longitude at sea, a chronometer would be set to the time of a place of known longitude, like Greenwich, England, the prime meridian. That time, carried to a remote location, could be compared to local time. Because one hour of difference in time equals 15 degrees difference in longitude, the difference in time between the chronometer and local time would yield local longitude. The instruments require careful handling to keep precise time. Although the original box for this instrument has not survived, most chronometers are fitted in a wooden box in a gimbal to remain level and compensate for the movement of a ship at sea.
label: Description
content: Robert Molyneux was a maker of chronometers and precision clocks in England. He was trained by Thomas Earnshaw and went into business for himself in the 1820s. In 1832 he moved his London business from 44 Devonshire Street to 30 Southampton Row and partnered with his son Henry in 1835. In 1842 the chronometer firm Birchall & Appleton moved to that address.
label: Description
content: Mechanism details:
label: Description
content: Escapement: Earnshaw spring detent
label: Description
content: Duration: 56-hour
label: Description
content: Power source: Spring drive with chain and fuse
label: Description
content: Balance spring: helical, blued steel
label: Description
content: Dial details:
label: Description
content: Engraved and silvered brass
label: Description
content: Indicates hours, minutes, seconds, and winding level up and down
label: Description
content: Inscription: “Molyneux & Sons / 30 Southampton Row, London / No 1436 / U.S. Army.”
label: Description
content: Blued steel spade hands
label: Description
content: Brass bowl with fittings to insert in gimbal
label: Description
content: No box
label: Description
content: No winding key
label: Description
content: References:
label: Description
content: 1. Britten, Frederick James. <i>Old Clocks and Watches & Their Makers.</i> London: E. & N. Spon Limited, 1922.
label: Description
content: 2. Gould, Rupert T. <i>The Marine Chronometer.</i> London: Holland Press, 1960.
label: Description
content: 3. Mercer, Tony. <i>Chronometer Makers of the World.</i> Essex: N.A.G. Press, 1991.
label: Description
content: 4. Whitney, Marvin. <i>The Ship’s Chronometer.</i> Cincinnati: American Watchmakers Institute Press, 1985.
label: Description
content: 5. Wood, Christopher. “Robert Molyneux's Astronomical Clocks and Chronometers,” <i>Antiquarian Horology 9</i> no. 4 (1975).
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
setName: label: See more items in
content: Work and Industry: Mechanisms
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content: Time and Navigation
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content: Measuring & Mapping
creditLine: label: Credit Line
content: Department of the Navy. Bureau of Ships
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: ME.314266
label: catalog number
content: 314266
label: accession number
content: 198140
objectType: label: Object Name
content: box chronometer, without case
physicalDescription: label: Physical Description
content: brass (overall material)
label: Physical Description
content: glass (overall material)
label: Physical Description
content: steel (overall material)
label: Measurements
content: bezel - from catalog card: 4 in; 10.16 cm
label: Measurements
content: backplate - from catalog card: 2 29/32 in; 7.366 cm
label: Measurements
content: overall: 2 1/8 in x 4 1/2 in; 5.3975 cm x 11.43 cm