Wednesday, 6 April 2011

Edmond Halley, 1677 and 1700

Portrait of Edmund Halley painted around 1687 by Thomas Murray.

While still a student at Oxford University, Halley began to observe the heavens with the Astronomer Royal at Greenwich John Flamsteed, only 10 years his senior, and published papers on sunspots and the solar system.  Influenced by Flamsteed’s project to compile a catalogue of northern stars, Halley proposed to do the same for the stars of the Southern Hemisphere which had not at that time been observed.  St. Helena was chosen being, then, the southern-most territory under British rule.  Charles II sent a letter to The East India Company desiring that Halley be granted free passage to St. Helena and, without bothering to take his degree and aged 20, in November 1676, he sailed for Jamestown on the Indiaman “Unity”.  Halley took with him a great sextant specially constructed of 51/2 foot radius fitted with telescopes in place of sights, his own 2 foot quadrant and several telescopes of different focal lengths up to 24 feet.  The weather in St. Helena proved less good for astronomical observations than Halley had hoped but despite this, by the time he returned home in 1678, he had recorded the celestial positions of 341 stars which he published in his star catalogue on his return to England along with a chart of the southern heavens.  On November 7th 1677 he also became the first astronomer to ever observe the complete transit of Mercury across the solar disc but this came to naught when bad weather in England deprived him of the other half of the observations.

Halley's Mount, Observatory Site, May 2010

Even though he had left Oxford without a degree he quickly found himself considered among the top astronomers of the day.  King Charles II decreed that The University of Oxford confer a degree on Halley without him having to take the exams.  Later in 1678 he was also elected a member of the Royal Society and at the age of 22 one of its youngest members.  All these honours given to Halley did not sit well with John Flamsteed.  Despite his earlier liking of the young college student, soon, he considered him to be an enemy.  When, in 1720, Halley succeeded Flamsteed as Astronomer Royal, Flamsteed’s widow was so angry that she had all of her late husband’s instruments sold so Halley could not use any of them.  He remained as Astronomer Royal until his death in 1742 at the age of 85, not surviving to see the predicted return of the comet, on December 25th 1758, which would later bear his name.

Halley’s Mount, Plaque, May 2010

Halley returned briefly to St. Helena in 1700.  Wanting more accurate magnetic charts of the Atlantic Ocean, their Lordships of the British Admiralty lent Halley a small sailing ship, the six-gun, three-masted, 52-foot "Paramore" (or "Paramour"), and instructed him to carry out a magnetic survey of the Atlantic Ocean and its bordering lands.  Perhaps considering this task an insufficient justification of the expedition, they also gave him a second one: "to stand soe farr into the South, till you discover the Coast of the Terra Incognita, supposed to lye between Magelan's Streights and the Cape of Good Hope".

The "Paramore" the first vessel built for the Royal Navy specifically for research set out in October 1698 on what is regarded as the first sea voyage undertaken for a purely scientific endeavour, but was troubled by both leaks and by a personal conflict between Halley and the navy officer in charge of the ship.  Halley had the man arrested and turned the ship back to England, where a court of inquiry upheld him and gave him sole command of the ship.  The "Paramore" set out again in September 1699 and by February 1st 1700 the ship had penetrated the Antarctic Convergence to reach below 52 degrees latitude, only 90n miles north of South Georgia.   After this the ship continued to Tristan da Cunha, St. Helena, Brazil, Barbados, Bermuda, Newfoundland and finally, at the end of August, back to England.

1 comment:

Ian Ridpath said...

See here for some stamps from St Helena showing Halley