09 Jul 2016

Today is the anniversary of the first Longitude Act, which gained royal assent on 9 July 1714. What was it and how did it affect our history here in Greenwich?

 It offered rewards to those who could find an accurate method for navigation at sea. Your latitude is relatively simple to discover, but finding your longitude proved a much more difficult task.


Longitude Act

Let’s set out the basics. The Act’s full title was ‘An Act for providing a Publick Reward for such Person or Persons as shall discover the Longitude at Sea’. Being able to find longitude, it noted at the start, was vital ‘for the Safety and Quickness of Voyages, the Preservation of ships, and the Lives of Men’. The Longitude Act offered rewards of up to £20,000 for a method of finding longitude at sea to within half a degree (equivalent to 2 minutes of time) after a six-week voyage to the West Indies. Smaller rewards were available for methods achieving lesser accuracy.

The Act also nominated a number of Commissioners of Longitude, later known as the Board of Longitude, to assess submissions and decide on rewards. They included the Astronomer Royal at Greenwich and other scientific, maritime and political leaders. The Commissioners could also grant smaller sums of money to help bring promising ideas to sea-trial.


Royal Observatory Greenwich

Whether the Act itself sped up a solution to the longitude problem is still up for debate, but the fact it was created shows the need for one. It was this need for accurate travel at sea that underlines our very history here in Greenwich, it led to founding of our Observatory in 1675 and drove forward amazing discoveries such as Harrison's famous timekeepers.



John Harrison's H1 Marine Chronometer


For more information on the search for longitude see our longitude blog