Edmond Halley

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Edmond Halley FRS (sometimes "Edmund"; IPA: /ˈɛdmənd ˈhɔːlɪ/) (November 8, 1656 – January 14, 1742) was an English astronomer, geophysicist, mathematician, meteorologist, and physicist.

Contents 1 Biography and career 2 Hollow Earth 3 Named after Halley 4 Notes and References 5 Bibliography 6 External links

[edit] Biography and career

Halley was born in Haggerston, London, the son of a wealthy soapboiler. As a child, Halley was very interested in mathematics. He studied at St Paul's School, and then, from 1673, at The Queen's College, Oxford. While an undergraduate, Halley published papers on the solar system and sunspots.

On leaving Oxford, in 1676, Halley visited the south Atlantic island of St. Helena with the intention of studying stars from the Southern Hemisphere. He returned to England in November 1678. In the following year he went to Danzig (Gdańsk) on behalf of the Royal Society to help resolve a dispute. Because astronomer Johannes Hevelius did not use a telescope, his observations had been questioned by Robert Hooke. Halley stayed with Hevelius and he observed and verified the quality of Hevelius' observations. The same year, Halley published Catalogus Stellarum Australium which included details of 341 southern stars. These additions to present-day star maps earned him comparison with Tycho Brahe. Halley was awarded his M.A. degree at Oxford and elected as a Fellow of the Royal Society.

In 1686 Halley published the second part of the results from his St. Helena expedition, being a paper and chart on trade winds and monsoons. In this he identified solar heating as the cause of atmospheric motions. He also established the relationship between barometric pressure and height above sea level. His charts were an important contribution to the emerging field of information visualization.

Halley married in 1682 and settled in Islington and the couple had three children. He spent most of his time on lunar observations, but was also interested in the problems of gravity. One problem that attracted his attention was the proof of Kepler's laws of planetary motion. In August 1684 he went to Cambridge to discuss this with Isaac Newton, only to find that Newton had solved the problem, but published nothing. Halley convinced him to write the Principia Mathematica Philosophiae Naturalis (1687), which was published at Halley's expense.

In 1690, Halley built a diving bell, a device in which the atmosphere was replenished by way of weighted barrels of air sent down from the surface. In a demonstration, Halley and five companions dived to 60 feet in the River Thames, and remained there for over an hour and a half. Halley's bell was of little use for practical salvage work, as it was very heavy, but he did make improvements to it over time, later extending his underwater exposure time to over 4 hours.^[1]

In 1693 Halley published an article on life annuities, which featured an analysis of age-at-death taken from archives in Breslau, a Polish-German town known for keeping meticulous records. This article allowed the British government to sell life annuities at an appropriate price based on the age of the purchaser. Halley's work strongly influenced the development of actuarial science. The construction of the life-table for Breslau, which followed more primitive work by John Graunt, is now seen as a major event in the history of demography.

In 1698, Halley was given the command of the 52 foot pink, Paramour (a pink was a form of small unrated vessel, akin to a sloop), 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 vessel and, in November 1698, sailed on what was the first purely scientific voyage by an English naval vessel. Unfortunately problems of insubordination arose, allegedly by officers resentful of being under a civilian's command. The Paramour returned to England in July 1699. Halley thereupon received a commission as a temporary 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.

In November 1703 Halley was appointed Savilian Professor of Geometry at Oxford University, 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. When it did it 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.^[2]

In 1720, Halley succeeded John Flamsteed as Astronomer Royal, a position which Halley held until his death at the age of 86. He was buried in the old graveyard in the Lee Terrace, Blackheath, across from the Parish Church of St. Margaret, in the same vault as Astronomer Royal John Pond; the unmarked grave of Astronomer Royal Nathaniel Bliss is nearby. It is about 30 minutes walk from the Greenwich Observatory.

[edit] Hollow Earth

In 1692 (Philosophical Transactions of Royal Society of London), Halley put forth the idea of a hollow Earth consisting of a shell about 500 miles (800 km) thick, two inner concentric shells and an innermost core, about the diameters of the planets Venus, Mars, and Mercury. Atmospheres separate these shells, and each shell has its own magnetic poles. The spheres rotate at different speeds. Halley proposed this scheme in order to explain anomalous compass readings. He envisaged the atmosphere inside as luminous (and possibly inhabited) and speculated that escaping gas caused the Aurora Borealis.^[3]

[edit] Named after Halley

• Halley's Comet — Halley predicted the comet's return.
• Halley crater on Mars.
• Halley crater on the Moon.
• Halley Research Station, Antarctica.
• Halley's method, for the numerical solution of equations.

An alternative (and incorrect) pronunciation of Halley's surname, to rhyme with "Bailey", has led to rock and roll singer Bill Haley punningly calling his backing band "His Comets" after Halley's Comet.

[edit] Notes and References

1. ^ London Diving Chamber (history) accessed on 6th Dec 2006
2. ^ Holberg, JB (2007). Sirius:Brightest Diamond in the Night Sky. Chichester, UK: Praxis Publishing, p. 41-42. ISBN 0-387-48941-X. 
3. ^ Carroll, Robert Todd (2006-02-13). hollow Earth. The Skeptic's Dictionary. Retrieved on 2006-07-23.

[edit] Bibliography

• Armitage, Angus, Edmond Halley (Nelson, 1966)
• Cook, Alan H., Edmond Halley: Charting the Heavens and the Seas (Oxford: Clarendon Press, 1998)
• Ronan, Colin A., Edmond Halley, Genius in Eclipse (Garden City, NY: Doubleday and Company, 1969)

[edit] External links

• Halley, Edmund, An Estimate of the Degrees of the Mortality of Mankind (1693).
• Halley, Edmund, Considerations on the Changes of the Latitudes of Some of the Principal Fixed Stars (1718) - Reprinted in R. G. Aitken, Edmund Halley and Stellar Proper Motions (1942)
• O'Connor, John J; Edmund F. Robertson "Edmond Halley". MacTutor History of Mathematics archive.  
• There is material on Halley's life table for Breslau on the Life and Work of Statisticians website: Halley, Edmond
• The National Portrait Gallery (London) has several portraits of Edmond Halley: Search the collection
• Edmond Halley Biography (SEDS)

Preceded by John Flamsteed

Astronomer Royal 1720–1742

Succeeded by James Bradley

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