While determining latitude was relatively easy,[2] early ocean navigators had to rely on dead reckoning to find longitude.

This was particularly inaccurate on long voyages without sight of land and could sometimes lead to tragedy, as during the Scilly naval disaster of 1707, which claimed the lives of nearly 2,000[3] sailors.

Following the Merchants and Seamen Petition, which called for finding an adequate solution and was presented to Parliament in May 1714, the Longitude Act was passed in July 1714.

[5] Other rewards were on offer for those who presented methods that worked within 80 geographical miles of the coast (being the most treacherous part of voyages) and for those with promising ideas who needed help to bring them to readiness for trial.

of 1767 held out £5,000 for improvements to Tobias Mayer's lunar tables and the Discovery of Longitude at Sea Act 1774 (14 Geo.