Photo: John Harrison's H4 chronometer - the device that finally solved the problem and the fore-runner of all precision watches. © National Maritime Museum, London.

Imagine, if you can, a time before radio and satellite navigation, when charting your position on the high seas was a near on impossible, yet vital task in the quest for wealth and empire.

Three hundred years ago a solution to the 'longitude problem' was so highly sought after that an act of parliament and a £20,000 reward (about £2m today) was established to find it.

With Heritage Lottery Fund help, the National Maritime Museum, London has bought a number of eighteenth century manuscripts and personal papers that provide a unique insight into the search for a solution.

Brought together in 1714, the Board of Longitude was put in place to examine the evidence of those who claimed to have solved the problem.

Image: it took him years, but eventually Harrison was able to claim the reward for finding the longitude. © National Maritime Museum, London.

The rare papers, belonging to board member, the second Viscount Barrington, reveal the deliberations that led to the dismissing of John Harrison's chronometer. It wasn't until 1772 when the self-educated carpenter and watchmaker took his invention to King George III, that he finally received his award.

Museum Director Roy Clare described the papers as "fascinating" and explained how they will "enable the museum's experts to reassess the discussions of the Board of Longitude."

According to Mr Clare they "shed new light on the events that led to Harrison eventually bypassing the board and making a personal appeal to King George III for the longitude prize to be awarded to him."

Alongside the papers, the museum has also acquired an unbound book, published in 1765 to make Harrison's case.

Image: the H1, the first of Harrison's chronometers, part of the museum's permanent collection. © National Maritime Museum, London.

The volume and a selection of Barrington's papers will, from August 18, join the four famous timekeepers invented by Harrison already on display at the museum.

It is perhaps fitting that the manuscripts should at last come to Greenwich, since the Royal Observatory was founded at the site in 1675 by King Charles II with the express intention of solving the 'longitude problem' through astronomy.

Sue Bowers, London Regional Manager at the HLF added: "We are thrilled to be able to help the museum ensure that these significant historic documents remain in the UK for greater public benefit."

"The manuscript gives a rare insight into the life and work of John Harrison and is all the more interesting for people alongside examples if his world famous clocks amid the museum's wider collection."