A self-taught clockmaker who accepted the challenge of creating a reliable method for determining longitude at sea, developing a series of accurate sea clocks over several decades.

Astronomer Royal and member of the Board of Longitude, known for his involvement in the lunar method of determining longitude and opposition to John Harrison's sea clocks.

The first director of the Royal Greenwich Observatory who made extensive observations of celestial objects, laying groundwork for future astronomers to advance navigation methods.

A prominent astronomer and the second Astronomer Royal who supported John Harrison's clockwork solution as a viable method for calculating longitude at sea.

Third Astronomer Royal and member of the Board of Longitude who supported the lunar method, indirectly conflicting with Harrison's clock method due to his role on the Board.

A naval officer who endorsed the effectiveness of Harrison's sea clock during his voyages, strengthening the argument for Harrison to receive the longitude prize.

An Italian astronomer who proposed using the moons of Jupiter to determine longitude, presenting an early, though not entirely practical, astronomical solution to the longitude problem.

A monarch who supported John Harrison's efforts by personally testing his clock, ultimately assisting in the recognition and reward of Harrison's work.

An English naval officer whose fatal navigational error highlighted the necessity of solving the longitude problem, ultimately leading to the Longitude Act.

A German mapmaker whose improvements in lunar position predictions were adopted by British astronomers to enhance lunar tables for longitude calculations.