During the great age of exploration, the "longitude problem" was the gravest of scientific challenges. Without the ability to determine longitude, sailors and their ships were lost at sea as soon as they lost sight of land. In 1714, desperate for a solution, England's Parliament offered 20,000 pounds (the equivalent of millions of dollars today) to anyone who could solve the problem. With all the skill and storytelling ability of a great novelist, Dava Sobel captures the dramatic story at the heart of this epic scientific quest.