Edmond Halley - Exploration

Exploration

In 1698, Halley was given the command of the Paramour, a 52-foot pink, so that he could carry out investigations in the South Atlantic into the laws governing the variation of the compass. On 19 August 1698, he took command of the ship and, in November 1698, sailed on what was the first purely scientific voyage by an English naval vessel. Unfortunately problems of insubordination arose over questions of Halley's competence to command a vessel. Halley returned the ship to England to proceed against officers in July 1699. The result was a mild rebuke for his men, and dissatisfaction for Halley, who felt the court had been too lenient. Halley thereafter received a temporary commission as a Captain in the Royal Navy, recommissioned the Paramour on 24 August 1699 and sailed again in September 1699 to make extensive observations on the conditions of terrestrial magnetism. This task he accomplished in a second Atlantic voyage which lasted until 6 September 1700, and extended from 52 degrees north to 52 degrees south. The results were published in General Chart of the Variation of the Compass (1701). This was the first such chart to be published and the first on which isogonic, or Halleyan, lines appeared.

The preface to Awnsham and John Churchill’s collection of Voyage and travels (1704), perhaps by John Locke or by Edmond Halley, made the link.

“Natural and moral history is embellished with the most beneficial increase of so many thousands of plants it had never before received, so many drugs and spices, such unaccountable diversity. Trade is raised to highest pitch, and this not in a niggard and scanty manner as when the Venetians served all Europe ... the empire of Europe is now extended to the utmost bounds of the Earth.”

In November 1703, Halley was appointed Savilian Professor of Geometry at the University of Oxford, his theological enemies, John Tillotson and Bishop Stillingfleet having died, and received an honorary degree of doctor of laws in 1710. In 1705, applying historical astronomy methods, he published Synopsis Astronomia Cometicae, which stated his belief that the comet sightings of 1456, 1531, 1607, and 1682 related to the same comet, which he predicted would return in 1758. Halley did not live to witness the comet's return, but when it did, the comet became generally known as Halley's Comet.

In 1716, Halley suggested a high-precision measurement of the distance between the Earth and the Sun by timing the transit of Venus. In doing so, he was following the method described by James Gregory in Optica Promota (in which the design of the Gregorian telescope is also described). It is reasonable to assume Halley possessed and had read this book given that the Gregorian design was the principal telescope design used in astronomy in Halley's day. It is not to Halley's credit that he failed to acknowledge Gregory's priority in this matter. In 1718 he discovered the proper motion of the "fixed" stars by comparing his astrometric measurements with those given in Ptolemy's Almagest. Arcturus and Sirius were two noted to have moved significantly, the latter having progressed 30 arc minutes (about the diameter of the moon) southwards in 1800 years.

In 1720, together with his friend the antiquarian William Stukeley, Halley participated in the first attempt to scientifically date Stonehenge. Assuming that the monument had been laid out using a magnetic compass, Stukeley and Halley attempted to calculate the perceived deviation introducing corrections from existing magnetic records, and suggested three dates (AD 920, AD 220 and 460 BC), the earliest being the one accepted. These dates were wrong by thousands of years, but the idea that scientific methods could be used to date ancient monuments was revolutionary in its day.

Halley succeeded John Flamsteed in 1720 as Astronomer Royal, a position Halley held until his death in 1742 at the age of 85. Halley was buried in the graveyard of the old church of St. Margaret, (now ruined) at Lee, South London . In the same vault is Astronomer Royal John Pond; the unmarked grave of Astronomer Royal Nathaniel Bliss is nearby.