Author Description

When Hipparchus invented the coordinate system of latitude and longitude, a rough latitude could be found, at least on land, with solar measurements, but it would take another two thousand years before longitude could be measured accurately at sea. Indeed, before the perfection of the sextant and chronometer in the 18th century, sailors navigated on long voyages without knowing where they were for much of the time. In 1991, in contrast, single-seater pest-spraying aircraft in the Sahara Desert routinely fixed their position with an accuracy of thirty yards using the Navstar Global Positioning System (GPS). The Navstar system, which employs 18 satellites around the earth, even boasts hand-held models costing less than a thousand dollars, within the budget of most weekend sailors.From Sails to Satellites traces the history of navigational science from the earliest systems of dead reckoning, to astrolabes and cross-staffs, to the ultra-modern guidance systems used by planes, ships, and missiles. Williams recounts the two-hundred-year Great Pursuit of Longitude, ranging from 1598, when Philip III of Spain offered lavish prizes for its discovery (and ironically brushed off Galileo, the only person alive who was on the right track); to 1759, when the most famous marine chronometer of all time, chronometer No. 4 built by John Harrison, a Yorkshire carpenter turned clockmaker, accurately measured longitude; to the development of the sextant, the first practical way to measure longitude. Williams discusses how in the 19th century great strides were made in the perfection of the pivoted needle compass, in nautical astronomy, in tidal prediction, and in marine lights, but it was with the Wright Brother's successful flight that navigation once again moved to the front ranks of science. He reveals how even as the first airplane flew in Kitty Hawk, scientists in America and Italy were developing radio direction-finding, while in Germany Anschutz-Kaempfe was developing the first g