‘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

‘And not likely to be’: Yet in 1736-7, just ten (10) years after Newton’s death in 1727 an early model of John Harrison’s marine clock, H-1, proved to be a reliable time-keeper aboard HMS Centurian  on its inaugural  voyage under Captain Proctor RN who unfortunately died as his ship reached home port and before he had brought his report up to date the

a supervised timed voyage – England to Lisbon.

Its acceptance however was  beset with difficulties.Mischievous tales  woven around H-1s1736  London to Lisbon voyage that included were typical of John Harrison’s long struggle for recognition.


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

Accurate time-keeping was essential for the calculation of longitude at sea.

With his invention a ‘pocket watch’ Harrison, a Yorkshire carpenter, had solved the problem.

His sea-going ‘pocket watch’ – gave a ship’s precise position when beyond sight of land.

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


‘The 1707 [Cloudisley Shovell]  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. ibid.

Throughout the centuries maritime disasters were common-place. In 1707, during  the reign of Queen Anne,  one of England’s worst recorded disasters occurred during the War of Spanish Succession (1701-14 ).

1707 – Gibraltar, September 29:  Britain had captured ‘The Rock’ from Spain in 1704. Three (3) years later – September 1707 –  a fleet of twenty-one (21) English ships set sail from there for England.

Aboard his flagship HMS Association dAdmiral Cloudesley Shovell, overall Commander of British fleets they were making  for Portsmouth their home base.

En-route Shovell’s vessels were battered by fierce gales. Dense sea-mist thrown up by rolling waves proved a nightmare for ships’ navigators making it all but impossible to plot a safe course.

Cornwell – October: To add to their woes, nearing home off the Cornish coast, heavy cloud obscured the night sky making celestial navigation impossible.

Scilly Isles: In pitch darkness some sailing masters lost their bearings altogether and failed to recognise their proximity to the rugged 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.

A lengthy investigation into the Cloudesley Shovell disaster concluded, due to prevailing weather conditions – with no moon or stars visible – ships’ navigators, limited y to ‘dead reckoning’,  had not been unable to determine their true position in relation to the land.

‘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.

Along with the ‘king’s ransom’ £20,000, reckoned now at more than £400 millions, Parliament established a Board of  Longitude to adjudicate submissions.

‘[But] 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.


1740: Another ten (10) years passed then came a second naval disaster of similar magnitude to that of Shovell’s off Cornwell.

‘Anson’s squadron took the Atlantic the old-fashioned way , on the strength of latitude readings, dead reckoning and good seamanship…A grand tragedy unfolded founded on the loss of their longitude at sea’. Sobel. ibid.

Despite the earlier H-1 Centurian (1737) success as yet in the prize money, had not been awarded. And this despite the strenuous efforts of John Harrison who, by 1740 had built three (3) improved versions of his ‘pocket-watch’.

Persistent hounding by the commissars – Astronomer Royals of Greenwich Observatory  – meant that when disaster overtook Admiral George Anson in 1740 ;‘the longitude clock stood on terra firma in Harrison’s home at Red Lion Square’. Sobel. ibid.


On the days 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

1740 – September: Although H-2 and H-3, improved models of Harrison’s initial chronometer were available, Commodore George Anson in HMS Centurion, due to strenuous opposition from Greenwich Observatory, took his squadron of warships to sea ‘the old fashioned way’ dead-reckoning and celestial navigation – using Luna Tables and Star Catalogues.

1741 – Cape Horn, March: Anson’s ships rounded Cape Horn in early March 1741. They were caught by gales so intense navigators had no idea where the squadron stood in relation to the land.

The Nautical Almanac, Luna Tables and Star Catalogues favoured by the Astronomer Royals of Greenwich Observatory may have been well suited to static land-based platforms.but not on a pitching weather deck in churning seas on starless nights.

In such circumstances these ‘tedious’ complicated ‘difficult to execute’ calculations required four  (4) men with hand-held instruments. It was the reason many seamen lost an eye.

To make matters worse Anson’s squadron had been at sea far longer than intended. Many crew developed scurvy ‘killing 6 to 10 men every day’.

As time went on, there was never enough crew to man the ships or repair sails shredded by ‘winds [that] carried rain, sleet and snow’.

Juan Fernandez: Finally the fleet reached Juan Fernandez where; ‘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.

Anson’s martyrs were added to Cloudesley’s lost souls. In part at least this was because the longitude prize money had unintended consequences.

£20,000 proved a heady brew when thrown amidst the warlocks of Greenwich Observatory whose intransigence was without doubt responsible for the loss of countless lives.


Greenwich Observatory: Complex Lunar Tables and Star Catalog had been devised a century earlier by Rev. John Flamsteed Britain’s first Astronomer Royal appointed by King Charles II in 1675.  Flamsteed held the post until his death in 1719.

Flamsteed, like Harrison, had felt the cruel lash of greed and duplicity. Edmond Halley of comet fame, with the connivance of Isaac Newton, had purloined, plagiarised and published Flamsteed’s Star Catalog without permission or attribution.

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

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

He 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’.

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

John Harrison died in March 1776 aged ‘exactly eighty-three years’. Dava Sobel covers fully the extraordinary story of the persecuted Yorkshire carpenter whose invention, the marine chronometer, 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 and finally 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’s son] 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 was Harrison’s chronometer in 1769 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.

James Cook and the crew of HMS Endeavour too ‘ha[d] been cruelly treated’. See: Captain Cook Caught Short

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