Until John Harrison came along, navigation of ships was a guesstimate at best. Egyptian sailors never ventured far from the land. Geographic landmarks guided them. Phoenician sailors shifted their eyes from the land to the skies and plotted their course by the North Star. In 1100 AD the Chinese created the first magnetized needle compass.
But it was John Harrison who solved one of the biggest maritime problems in history. In 1714 the British government established the Board of Longitude and offered a reward of 20,000 pounds — about $6 million today — to anyone who could create a device that would provide longitude within a half-degree or two minutes of time.
Some of the greatest minds in Europe accepted the challenge. But it took Harrison, a self-educated clockmaker, to create the marine chronometer. The marine chronometer became a standard stowaway on ships and men on the Seven Seas were able to find their way home without having to stop and ask for directions.
Today the marine chronometer is seldom used, but is required on most vessels. What bumped it? GPS — The Global Positioning System.