Posts Tagged ‘chronometer’

CAPTAIN COOK – JOHN HARRISON – CHARLES GREEN: THREE YORKSHIRE MEN WALKED INTO A BAR

Wednesday, August 23rd, 2017

‘He [John Harrison] wrested the world’s whereabouts from the stars, and locked the secret in a pocket watch’. Dava Sobel, Longitude, Fourth Estate, London, 1998

Harrison H-4 Chronometer

Since earliest times sea-faring nations England, Portugal, France, Spain and the Netherlands vied with each other to solve – the Holy Grail of Navigation – longitude – calculating with precision a ship’s position while at sea beyond sight of land.

1714  – Westminster: Legislation, The Act of Longitude 1714, followed an enquiry into England’s first recorded 18th century maritime disaster.

In 1707 off the Cornish coast in heavy weather six (6) of Admiral Clowdisley Shovell’s ships lost their bearings and were dashed to pieces on the Scilly Isles with the loss of 1500 lives.

As a consequence in 1714 The Board of Longitude was established to invite and evaluate submissions and award a prize of £20,000 to whom-so-ever solved the problem of longitude at sea.

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THE THIRD MAN – CHARLES GREEN

Tuesday, August 15th, 2017

‘The grim roll-call broke his [Cook’s) heart…the death of the astronomer Charles Green marked a wave of those who ‘departed this life’….By the end of January [1771] they had barely enough men to man the ship [HMS Endeavour]’. Vanesssa Collingridge, Captain Cook, The Life, Death and Legacy of History’s Greatest Explorer, Ebury Press, 2002

Charles Green son of ‘a prosperous’ free-hold Yorkshire farmer was born in Swinton towards the end of 1734. He received a broad education with a strong emphasis on science.

John his elder brother took Holy Orders and established a school in Soho, London where Charles found his ‘heavenly passion’ astronomy. After graduating he stayed on for a time teaching mathematics.

In 1760 Charles applied successfully for the position of Assistant Astronomer at Greenwich Observatory where in that capacity he served three (3) Astronomer Royals.

In 1742 James Bradley first of these men succeeded Edmond Halley of comet fame. In 1720 Halley himself had followed John Flamsteed the inaugural Astronomer Royal, appointed by King Charles II in 1675. Flamsteed remained at Greenwich until his death in 1720. Halley then held the post for twenty-two (22) years from 1720 to 1742.

Bradley’s tenure too was lengthy he reigned between 1742 and 1762. Bradley is celebrated principally for his work on the speed of light. In 1728 he estimated light moved at the speed of 295,000 km (183,000 miles) per second.

Three (3) centuries later – 2017 – Bradley’s calculations were amended to 299,790 km (186,290 miles) per second.

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

If only Bradley had stuck to light and left time and longitude to Mr. John Harrison inventor of an accurate marine chronometer – a sea-going ‘pocket-watch’ – many a sea-farer would not have met a watery end.

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MOON VERSUS MACHINE

Tuesday, August 15th, 2017

Compared with that of Banks, Mr. Green’s equipment was comparatively modest. On May 5th, 1768, at a meeting of Council of the Royal Society it was resolved that the instruments for the use of the Observers of the South Latitudes be the following:

Two [2] reflecting telescopes of two [2] foot focus…[1] brass Hadley’s sextant, [1] barometer bespoke of Mr Ramsden, [1] Journeyman’s Clock bespoke by Mr Skelton, two [2] Thermometers of Mr Bird, [1] Stand for Bird’s Quadrant, [1] dipping needle bespoke by Mr Ramsden’. H.C. Cameron, Sir Joseph Banks, Angus and Robertson, Sydney, 1966

Mr. Charles Green, former Assistant to James Bradley and Nathaniel Bliss, Astronomer Royals of Greenwich Observatory, was engaged by the Royal Society to represent them and assist Lieutenant James Cook RN observe and record the Transit of Venus due to take place at Tahiti on 3rd June 1769

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

Here two (2) of a plethora of questions must be asked. Who was Mr. Green and why was John Harrison’s marine chronometer – H-4 – not among his equipment when he set off aboard HMS Endeavour with Lieutenant James Cook for Tahiti to observe the Transit of Venus? See: Captain Cook, John Harrison, Charles Green – Three Yorkshire Men Walked Into A Bar

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LOTTO AND LONGITUDE

Wednesday, August 9th, 2017

‘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

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