overall: 11 in x 10 3/4 in x 11 in; 27.94 cm x 27.305 cm x 27.94 cm
United States: Massachusetts, Boston
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.
Escapement: Earnshaw, spring detent, later pattern
Power source: Spring drive with chain and fuse
Bezel screwed and milled
Crystal flat and plain
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
Box: solid wood, three-part, glazed center section
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. <i>The Marine Chronometer.</i> London: Holland Press, 1960.
2. Whitney, Marvin E. <i>The Ship's Chronometer.</i> Cincinnati: American Watchmakers Institute Press, 1985.