The new Longitude Prize announced yesterday is exciting but it’s a real shame that some of the coverage implies that Harrison was the ‘sole’ discoverer of the solution to the original problem back in the 1750s. See http://www.telegraph.co.uk/science/science-news/10841125/Calling-all-geniuses-for-the-new-Longitude-Prize.html
The truth is quite different of course, as I’ve documented in some detail in ‘Sextant’. While Harrison’s prototype ‘H4’ watch was indeed a brilliant success, and paved the way for even better chronometers made by other craftsmen, the astronomers simultaneously achieved an extraordinary breakthrough with the ‘lunar distance’ method of determining the time. Much of the credit was due to Tobias Mayer’s new tables predicting the moon’s complex motions.
In reality, the chronometer method and the lunar distance method of finding the longitude were to be used in tandem for many years to come, as is readily apparent from the logs of all the great navigators of the age, right through until the 1830s. And both methods, of course, depended on observations made with a sextant!