“skilled. The invention of the marine chronometer in the eighteenth century by the self-taught British carpenter and clock maker John Harrison resulted in a supremely reliable clock unaffected by changes in humidity and the ship’s motion. Harrison’s marine chronometer, which found its way onto most large merchant vessels, was set constantly at Greenwich Mean Time (GMT). Each day, when the celestial latitude was calculated by shooting the sun, the navigator would compare the ship’s local time (the local hour angle) with the Greenwich time (the Greenwich hour angle), and, using published tables, be able to calculate the distance in degrees east or west from the Prime Meridian.V Soon after the American Revolution, the United States made its own contribution to navigation, one, arguably, as important as Harrison’s chronometer. This was The New American Practical Navigator, first published in 1802 by twenty-nine-year-old Nathaniel Bowditch, a self-taught mathematician from Salem. The grammar school dropout had taken only one trip to Manila, serving as a supercargo. But with typical Yankee dash and impudence, he noted every inconsistency in the calculations of the then-bible of navigation, John Hamilton Moore’s The Practical Navigator. The result, an entirely new guide, became a massive best seller, was adopted by merchant captains and the US Navy as the gold standard for navigation, and has never gone out of print. Ujifusa, Steven. Barons of the Sea: And their Race to Build the World's Fastest Clipper Ship (p. 97). Simon & Schuster. Kindle Edition. Ujifusa, Steven. Barons of the Sea: And their Race to Build the World's Fastest Clipper Ship (pp. 96-97). Simon & Schuster. Kindle Edition. Ujifusa, Steven. Barons of the Sea: And their Race to Build the World's Fastest Clipper Ship (p. 96). Simon & Schuster. Kindle Edition. ”
