Posts Tagged ‘lunar tables’

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 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 after taking Holy Orders established a school in Soho, London there Charles found his ‘heavenly passion’ astronomy. After graduating he stayed on for a time to assist John with the teaching of mathematics.

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

James Bradley first of these men had, in 1742 succeeded Edmond Halley of comet fame, who died during that year. Halley held the post of Astronomer Royal for twenty-two (22) years from 1720-1742.

Bradley’s tenure too was lengthy he reigned until his death in 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.

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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MALICIOUS MASKELYNE

Monday, August 14th, 2017

1663 – England: In 1663 during the reign of King Charles II (1660-1685) a collection of ‘enquiring men of science’ – the ‘Invisible College’ – morphed into the Royal Society.

A century later under the patronage of King George III between 1760 and 1820 the Society flowered into one of the world’s most celebrated scientific institutions.

1767: With the Transit of Venus in the offing – 3 June 1769 – its second appearance in that decade – the Society petitioned King George III for financial support.

‘The Transit was more than just an astronomical curio, it was the key to a wealth of information about the universe, information that would be seized upon by the intensely curious men of science who characterised the age’. Vanessa Collingridge, Captain Cook, The Life, Death and Legacy of History’s Greatest Explorer, Random House, 2003 

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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. His invention the sea-going ‘pocket watch’ 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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