Longitude Act

The Longitude Act was an Act of Parliament passed in Great Britain in 1714 (12 Anne c. 15). Its formal title was "An Act for Providing a Public Reward for such Person or Persons as shall Discover the Longitude at Sea." It offered a system of rewards, commensurate with the accuracy achieved, to anyone who could devise a practical method for determining a ship's longitude while at sea.

The Act was spurred by maritime disasters attributable to the difficulty of accurately calculating longitude, most notably the Scilly naval disaster of 1707. This disaster highlighted the urgent need for a reliable method to determine a ship's east-west position.

The Act established the Board of Longitude, a body of commissioners tasked with evaluating proposed methods and awarding the promised prizes. The Board included leading scientists, mathematicians, and naval officers of the time.

The rewards varied depending on the accuracy achieved. The Act stipulated specific sums for finding longitude within one degree, two-thirds of a degree, and one-half of a degree of the true value. The measurement was to be tested by voyages to the West Indies.

While various astronomical methods were proposed, the solution ultimately came in the form of accurate marine chronometers. John Harrison, a clockmaker, dedicated his life to developing such a clock. Although his chronometers eventually proved successful, Harrison faced significant resistance from the Board of Longitude, which initially favored astronomical solutions. The Act was amended over time to reflect ongoing technological advancements and to better define the testing procedures and criteria for awarding the prizes.

The Longitude Act is significant not only for the scientific advancements it spurred but also for the precedent it set for government-sponsored scientific research and development to address practical problems. It remained in effect until it was repealed in 1828 and replaced with new legislation.