Wm. Bond & Son Box Chronometer

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This instrument is a specialized timekeeper originally designed for finding longitude at sea and later used everywhere as a source of portable precise time. It has an English-made chronometer movement, finished by the firm William Bond & Son of Boston and fitted with the Bond break-circuit device, electrical equipment to permit the telegraphing of time signals. The Smithsonian’s Astrophysical Observatory used the instrument. The chronometer’s wooden box fits into a padded basket for extra protection.
Mechanism details:
Escapement: Earnshaw, spring detent, later pattern
Duration: 56-hour
Power source: Spring drive with chain and fuse
Bowl details:
Brass bowl
Brass gimbals
Bezel screwed and milled
Crystal flat and plain
Dial details:
Engraved and silvered brass
Indicates hours, minutes, seconds, winding level up and down, 24-hour dial
Inscription: "WM. BOND & SON, / Boston. No. 586" on dial; "WM. BOND & SON'S, BREAKCIRCUIT. / U. S. A." on silvered inside of bezel
Hands: Gold, spade, with blued seconds and Up & Down hands
Case details:
Box: solid wood, three-part, glazed center section
Brass corners
Mother of pearl key escutcheon
Inscriptions: "WM. BOND & SON. / Boston. No 521 / BREAK CIRCUIT" on nameplate
"BOND / 521" on small oval plate in bottom of box
Carrying case: Basket, with padding
1. Gould, Rupert T. The Marine Chronometer. London: Holland Press, 1960.
2. Whitney, Marvin E. The Ship's Chronometer. Cincinnati: American Watchmakers Institute Press, 1985.
date made
ca 1870
Wm. Bond & Son
place made
United States: Massachusetts, Boston
Physical Description
brass (overall material)
glass (overall material)
steel (overall material)
wood (container material)
overall: 11 in x 10 3/4 in x 11 in; 27.94 cm x 27.305 cm x 27.94 cm
ID Number
catalog number
accession number
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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