Item History: Fixing a ship’s position in latitude and longitude gradually became part of the mariner’s routine in the 19th century. To find latitude, the distance north or south of the equator, mariners had long used a succession of increasingly accurate instruments to measure the angle above the horizon of the sun at noon or the star Polaris at night. Determining longitude, a distance east or west of a reference meridian was much harder. Although predictions that an accurate clock would solve the problem of finding longitude at sea had surfaced since the 16th century, no such clock existed until the 18th century.
A stunning technical breakthrough came when John Harrison, a talented English carpenter, built five marine timekeepers between 1735 and 1770 that incontestably demonstrated the utility of a clock at sea. Inspired by Harrison’s innovations, other makers in England and France contributed refinements to Harrison’s designs. The modern marine chronometer was born.
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, Massachusetts. 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 Cyrus. 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.
The chronometer by Bond’s time had already assumed standard features. Most of them ran from the force of an unwinding spring and had a special feature—the spring 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 eighteenth-century French 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.
Edward S. Holden, Memorials of William Cranch Bond and His Son George Phillips Bond (New York, 1897).
Carlene E. Stephens, “Partners in Time: William Bond & Son of Boston and the Harvard College Observatory,” Harvard Library Bulletin 35 (Fall 1987): 351-84.
__________. On Time: How America Has Learned to Live by the Clock (Boston: Bullfinch Press of Little Brown, 2002), 30-34.