On his second voyage to the South Seas, Captain James Cook brought a carefully crafted replica of Harrison’s fourth clock and swore by it, but to no avail.

Longitude Summary and Study Guide | SuperSummary

By contrast, John Harrison imagined and built the unimaginable: a clock that told perfect time at sea, known today as the chronometer. This increased the likelihood of short rations, [3] scurvy or starvation leading to poor health or even death for members of the crew and resultant risk to the ship. In "Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time," I was taken on an exhilarating journey through the fascinating world of 18th-century navigation and the brilliant mind of John Harrison.A number of scientists, among others Galileo and Huygens, made various efforts but were unable to solve the longitude problem, but their solutions were unsatisfactory. Under such circumstances, countries were eager to discover new, secret paths, and that required an effective way to determine longitude. The British legislature set up a Board of Longitude which had the authority to offer an award to anyone who could solve the problem.

Longitude Summary | Dava Sobel Longitude Summary | Dava Sobel

He does so through an appealing narrative, making use of first-hand accounts whose sources he describes in his notes at the end (though, disappointingly he cites nothing directly in the text). Desperate for a fair hearing, Harrison and his grown son, William, beseeched King George III for help.

The sailors while at the ocean found it pretty straightforward to find their current latitude - which is drawn parallel to each other while girdling the globe – by measuring the height of the sun or any known celestial bodies.