When Dava Sobel's Longitude was published to universal acclaim in 1995, readers voiced only one regret: that it was not illustrated. Now, William Andrewes, the man who organized and hosted the Longitude Symposium that inspired her book, has joined Dava Sobel to create a richly illustrated version of her classic story. The Illustrated Longitude recounts in words and images the epic quest to solve the thorniest scientific problem of the seventeenth and eighteenth centuries. Throughout the great age of exploration, sailors attempted to navigate the oceans without any means of measuring their longitude: All too often, voyages ended in total disaster when both crew and cargo were captured or lost upon the rocks of an unexpected landfall. Thousands of lives and the fortunes of seafaring nations hung on a resolution. To encourage a solution, governments established major prizes for anyone whose method or device proved successful. The largest reward of £20,000-truly a king's ransom-was offered by the British Parliament in 1714. The scientific establishment-from Galileo to Sir Isaac Newton-had been certain that a celestial answer would be found and invested untold effort in this pursuit. In stark contrast, one man, John Harrison, imagined and built the unimaginable: a clock that solved the problem by keeping precise time at sea, called today the chronometer. His trials and tribulations to win the prize throughout a forty-year obsession are the culmination of this remarkable story. The Illustrated Longitude contains the entire original narrative of Longitude, redesigned to accompany 178 images chosen by Will Andrewes: from portraits of every important figure in the story to maps, diagrams, and photographs of scientific instruments, especially John Harrison's remarkable clocks. Andrewes's elegant captions emphasize the scientific and historical events surrounding the images, and they tell their own dramatic story of longitude, paralleling and illuminating Dava Sobel's memorable tale.