‘But by reason of the motion of the Ship, the Variation of Heat and Cold, Wet and Dry, and the Difference of Gravity in different Latitudes, such a watch hath not yet been made”. And not likely to be, either, he implied’.  Isaac Newton cited, Dava Sobel, Longitude, Fourth Estate, London, 1998

‘Not likely’ however in 1736 on a timed voyage, England to Lisbon aboard HMS Centurian, an early model of John Harrison’s  marine clock the H-1 – proved to be a reliable time-keeper.

‘He [Harrison] succeeded, against all odds, in using the fourth – temporal – dimension to link points on the three-dimensional globe’. Sobel. ibid.

Accurate time-keeping was essential for the calculation of longitude and John Harrison a Yorkshire carpenter solved the problem of longitude with his sea-going ‘pocket watch’ that gave a ship’s precise position when beyond sight of land.

‘John Harrison, the man who solved longitude in 1759’. Peter Ackroyd, Revolution, Macmillan, London, 2016

On the day before reliable time-keeping, the skies were used as a giant clock’.Vanessa Collingridge, Captain Cook, The Life, Death and Legacy of History Greatest Explorer, Random House, London, 2003

Throughout the centuries maritime disasters were common-place. One of England’s worst recorded disasters occurred during the reign of Queen Anne in the middle of the War of Spanish Succession (1701-1714) .

1707 – 29 September: At the end of September 1707 a fleet of twenty-one (21) English ships led by HMS Association flagship of Admiral Cloudesley Shovell, overall Commander of British fleets set sail from Gibraltar, captured in 1704 from Spain, for Portsmouth their home base.

Shovell’s vessels were battered by fierce gales and as they neared England dense sea-mist thrown up by recurring storms proved a nightmare for ships’ navigators making it all but impossible to plot a safe course.

 1707 – 22 October: To add to their woes, when off the coast of Cornwall heavy cloud obscured moon and stars, celestial navigation became impossible. In the darkness some sailing masters lost their bearings and failed to recognise their proximity to the Isles of Scilly.

Four (4) vessels including HMS Association crashed onto rocks and sank with all hands including Admiral Shovell. Two (2) more ships capsized, overall mortality was reckoned at 1500 souls.

 ‘The 1707 incident, so close to the shipping centres of England, catapulted the longitude question into the forefront of national affairs [and] underscored the folly of ocean navigation without a means for finding longitude’. Dava Sobel, Longitude, Fourth Estate, London, 1998

 A lengthy investigation into the Cloudesley Shovell disaster concluded, due to prevailing weather conditions, ships’ navigators had been unable to determine their true position in relation to the Cornish coast.

‘The souls of Sir Cloudesley’s lost sailors – another thousand martyrs to the cause precipitated the famed Longitude Act of 1714, in which Parliament promised a prize of £20,000 for a solution to the longitude problem’. Sobel. ibid

So why then by 1740 when a second naval disaster of similar magnitude occurred and, nearly a half-century after Parliament passed the Longitude Act of 1714 authorising a prize of £20,000 reckoned now at more than £400 million, had the prize not been awarded?

‘When John Harrison arrived in London in the summer of 1730, the Board of Longitude was nowhere to be found. Although that august body had been in existence for more than fifteen years, it occupied no official headquarters in fact, it had never met’. Sobel. ibid.

By 1740 Harrison had built three (3) versions of his mechanical ‘watch’ but persistent hounding by the commissars – Astronomer Royals – of Greenwich Observatory meant that when another maritime disaster occurred; ‘the longitude clock stood on terra firma in Harrison’s home at Red Lion Square’. Sobel. ibid.

 1740 – September: Commodore George Anson in HMS Centurion had led, in ‘the old fashioned way’ a squadron of six (6) warships to sea although improved models of Harrison’s chronometer H-2 and H-3 were available.

‘Anson’s squadron took the Atlantic the old-fashioned way, on the strength of latitude readings, dead reckoning and good seamanship’. Sobel. ibid.

1741 – March: Anson’s ships rounded Cape Horn in early March 1741 only to be caught by gales so intense navigators had no idea where the squadron stood in relation to the land and as Dava Sobel has it; ‘a grand tragedy unfolded, founded on the loss of their longitude at sea’.

The squadron had been at sea longer than intended and many crew developed scurvy ‘killing 6 to 10 men every day’. As time went on, there was never enough man-power to repair sails shredded by ‘winds [that] carried rain, sleet and snow’. 

Finally, the ship’s reached Juan Fernandez where Admiral ‘Anson helped carry the hammocks of sick sailors ashore, then watched helplessly as the scourge picked off his men one by one…until more than half of the original five hundred were dead and gone’.  Sobel. ibid.

‘The old fashioned way’ celestial navigation used complex Lunar Tables. These Tables had been devised a century earlier by Rev. John Flamsteed during his long tenure as Britain’s first Astronomer Royal. Appointed by King Charles II in 1675 he held the post until his death in 1719.

Flamsteed’s Luna Tables and Star Catalogues may have been well suited to static land-based platforms but less so on a pitching deck in churning seas.

In such circumstances, complicated calculations made with hand-held instruments, were ‘difficult to execute’ and here-in lay the reason many a seaman lost an eye. Dense cloud and starless nights magnified a navigator’s problems.

Flamsteed himself had felt the cruel lash of duplicity. Edmond Halley of comet fame, with the connivance of Isaac Newton, purloined, plagiarised and during the Flamsteed’s lifetime published his work without permission or attribution. In 1720 Halley, following Flamsteed’s death, was appointed Astronomer Royal.

Meantime Admiral Anson’s martyrs were added to Sir Cloudesley’s lost souls and this, in part at least, because the Longitude Prize of £20,000 had unintended consequences.

‘The Board of Longitude was top-heavy with astronomers, mathematicians and navigators’. Sobel. ibid.

This vast sum proved a heady brew when thrown amidst the warlocks of Greenwich Observatory whose intransigence was without doubt responsible for the loss of countless lives.

 ‘John Harrison, the man who solved longitude in 1759’. Peter Ackroyd, Revolution, Macmillan, 2016

In the mid 1760s battle-lines were drawn between moon and machine. The Observatory’s Rev. Nevil Maskelyne, Britain’s fifth Astronomer Royal, clung to outmoded 17th century thinking and old technology – Luna Tables versus the mechanical sea-going clock. ‘See: Moon Versus Machine 

1765:  Maskelyne, one hundred (100) years after King Charles II founded Greenwich Observatory in 1675, published the first edition of his major work The Nautical Almanac’.

Maskelyne was certain theNautical Almanac’, based on the relationship between Sun, Moon and Stars as a means of calculating longitude on the high seas, would deliver him the ‘king’s ransom’ £20,000.

John Harrison died in March 1776 aged ‘exactly eighty-three years’. Dava Sobel covers fully the extraordinary story of the Yorkshire carpenter who invented the marine chronometer and solved the problem of longitude. See: Cook, Harrison, Green – Three Yorkshire Men Walked Into A Bar – Maskelyne

‘A true-life thriller, jam-packed with political intrigue, international warfare, personal feuds and financial skullduggery’. Francis Wheen, Daily Mail.

Longitude tells of Harrison’s painstaking efforts to perfect his ‘watch’ and of his unending frustrations as he butted heads with the dictators of the Longitude Board.

Sobel catalogues the merciless persecution of Harrison by a succession of Astronomer Royals, James Bradley, Nathaniel Bliss then the Rev. Nevil Maskelyne who held the position from 1765 to 1811. See: Malicious Maskelyne

 ‘Rarely have I enjoyed a book as much as Dava Sobel’s Longitude. She has an extraordinary gift of making difficult ideas clear’. Patrick O’Brien, Daily Telegraph (London).

For more details on Dava Sobel’s book, Longitude see:


 ‘In January 1772 William [Harrison] wrote the king [George III] a poignant letter covering the history of his father’s hardships with the Board of Longitude and the Royal Observatory…the king is reported to have muttered under his breath “These people have been cruelly treated”. Sobel. ibid.

And where a mere three (3) years earlier, in 1769, was Harrison’s chronometer when Lieutenant James Cook RN sailed HMS Endeavour deep into the South Seas in search of the fabled Great South Land?

‘[H-4 [was] bolted to a window seat in the [Greenwich] Observatory’. Sobel. ibid. See: Captain Cook Caught Short



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