In the 19th century, portable marine timekeepers called chronometers became indispensable instruments for determining longitude at sea. To use a marine chronometer, outbound sailors would set their timepieces to the time of a known port's longitude—say Greenwich, England, or Boston. Once at sea, mariners calculated their position east or west of that place by converting the difference in time on the chronometer and local ship time into distance, 15 degrees of longitude for every hour.
Tradition says this timekeeper was the first seagoing chronometer made in America. Twenty-three-year-old Boston clockmaker William Cranch Bond constructed it during the War of 1812. When Bond made his instrument, no chronometer industry existed in the United States, and British makers dominated the world market.
Bond's instrument went to sea only once, on a voyage to Sumatra in 1818 aboard the U.S. Navy vessel <I>Cyrus.</I> Chronometers were uncommon aboard American ships at the time, and the Cyrus's captain warned Bond to read the record of the instrument's performance with a critical eye.
Invented half a century earlier by John Harrison in England and Pierre LeRoy and Ferdinand Berthoud in France, the chronometer by Bond's time had already assumed standard features. Most of the chronometers ran from the force of an unwinding spring and had a special feature—the detent escapement. Suspended from gimbals in a wooden box, the instrument remained horizontal even on a heaving ship. Bond's timekeeper was different. Unable or unwilling to get British spring steel in wartime, he borrowed an 18th-century Berthoud design and built his timekeeper to run with power from a falling weight.
William Bond & Son, a family firm begun by William Cranch Bond's father in 1793, became one of America's best-known chronometer dealers. As the business flourished, the younger Bond pursued his passion for astronomy. In 1839 he became the first director of the Harvard College Observatory.