Longitude, or rather the “starting point” for lines of longitude, is entirely arbitrary. But how far away were you from the nearest charted island? And were you to the east of it, or the west? So you could figure out how far away from the equator or the poles. Latitude corresponds both to the sun’s altitude in the sky (at noon) and to the altitude of certain stars (if you are in the Northern Hemisphere, Polaris is a good choice) at night.

Latitude was relatively easy-well, easy enough once you dealt with the pitching deck, the storms, and the scurvy. I’m not sure how to describe how lost you could be, out there on the ocean, no longer in sight of shore. In the days-centuries-prior to GPS, you could get lost. GPS might not be great at giving directions, but that doesn’t mean you’re lost. Thanks to GPS, we can forget that calculating longitude without the help of a network of satellites is difficult and requires great mathematical and engineering expertise. I don’t use it that much personally, because I don’t tend to go anywhere, but I’m sure all this technology I love to use makes use of GPS. In stark contrast, one man, John Harrison, dared to imagine a mechanical solution.įull of heroism and chicanery, brilliance and the absurd, LONGITUDE is also a fascinating brief history of astronomy, navigation and clockmaking.I take GPS for granted. The scientific establishment throughout Europe - from Galileo to Sir Isaac Newton - had mapped the heavens in both hemispheres in its certain pursuit of a celestial answer. Countless quacks weighed in with preposterous suggestions. The quest for a solution had occupied scientists and their patrons for the better part of two centuries when, in 1714, Parliament upped the ante by offering a king's ransom (£20,000) to anyone whose method or device proved successful. Thousands of lives, and the increasing fortunes of nations, hung on a resolution. Lacking the ability to measure their longitude, sailors throughout the great ages of exploration had been literally lost at sea as soon as they lost sight of land.

'Sobel has done the impossible and made horology sexy - no mean feat' New ScientistĪnyone alive in the 18th century would have known that 'the longitude problem' was the thorniest scientific dilemma of the day - and had been for centuries. With a new Foreword by the celebrated astronaut Neil Armstrong.

The tenth anniversary edition of the dramatic human story of an epic scientific quest: the search for the solution of how to calculate longitude and the unlikely triumph of an English genius.

Book longitude sobel