Edmond Halley

English astronomer

• Born: November 8, 1656
• Birthplace: Haggerston, near London, Shoreditch, England
• Died: June 14, 1742
• Place of death: Greenwich, England

Among his many scientific achievements, Halley’s best-known accomplishment was to solve the riddle of the orbits of comets. In particular, he predicted that the one seen in 1682 would return in 1759. This comet was later named for him.

Early Life

The details of the life of Edmond Halley (HAL-ee) are only sketchily known, since most of his private papers and correspondence have been lost. Some facts have been collected from the papers of colleagues, relations, and friends, but many gaps remain. It is known that he was born on November 8, 1656, in Haggerston, on the outskirts of London. His father, a soap boiler, belonged to the monied merchant class and provided for Halley throughout his education. Halley attended St. Paul’s School, where he became the school captain, and furthered his studies at Queen’s College, Oxford, in 1673. It was there that he first formally studied astronomy, beginning a regular correspondence with John Flamsteed, who was then astronomer royal. The older man took the young Halley under his wing, and with Flamsteed’s guidance, Halley made one or two minor contributions to the mathematics of astronomy.

In 1676, Halley ventured to Saint Helena in the Southern Hemisphere on an expedition to study the stars there. He was supported during this time by his father, who was still comparatively wealthy, despite having suffered some property losses during the 1666 Great Fire of London. Halley had an allowance of three hundred pounds a year. Although conditions at Saint Helena were overcast, he achieved his aim and on his return published the Catalogus Stellarum Australium (1678; Australian stellar catalog) and a planisphere. His work found favor with King Charles II, since Halley regrouped a particular constellation of stars and renamed them Charles’s Oak in his honor.

Halley was awarded an M.A. at Oxford for this work, and his endeavors brought him to the attention of the Royal Society (the somewhat august body to which all the leading scientists of the day belonged). The society made him a fellow. He was asked by the Royal Society to visit the Dutch astronomer Johannes Hevelius at Danzig to investigate his methods of star observation. With telescopic sights now in vogue, the society believed that Hevelius’s methods were old-fashioned and therefore inaccurate. Halley reported in Hevelius’s favor (much to Flamsteed’s annoyance and causing a breach of friendship between the two that lasted some forty years).

While Halley’s scientific reputation soared with these projects, however, his personal reputation was surrounded by rumor and innuendo. On the Saint Helena expedition, his name was coupled with that of a married woman who found herself pregnant on Halley’s departure, and during the Danzig trip, gossip abounded about Halley’s relationship with Elisatetha Hevelius, Johannes’s wife. In the coffeehouses, Halley appears to have been labeled a womanizer, and his reputation offended some of his more straitlaced colleagues.

In 1680, Halley traveled to Paris to work with Gian Domenico Cassini, the director of the Paris Observatory. The two made detailed observations of a new comet that had appeared. This was not the comet that would later bear his name, but this kind of painstaking observational work was to be Halley’s hallmark throughout his scientific career. He returned to London, perhaps because his father could no longer support him, and married Mary Tooke in 1682. They settled in Islington, London, and remained married until her death in 1736. Little is known about her or about their life together.

Life’s Work

The next period of Halley’s life was bound up with his own meticulous observations, the continual wranglings of the Royal Society, and his friendship with Sir Isaac Newton , undoubtedly the greatest scientist of that generation. The Royal Society at that time contained some of the most prominent men of the seventeenth century—Sir Christopher Wren , Samuel Pepys , Robert Hooke , Flamsteed, and Newton—and the papers and theories that were presented at its meetings were in the vanguard of scientific research.

The late seventeenth century was an exciting period in the history of astronomy. Following the pioneering observational work of Galileo and Johannes Kepler, planets were known to travel in regular, elliptical orbits around the sun. The problem facing the scientists of the Royal Society was to explain the mechanics of this occurrence, demonstrating from first principles, mathematically, why it should be so. Many of the eminent men of the day were tackling the challenge, and the race was on to reach the solution first. Halley played no small part in this story.

In 1684, Halley became the clerk of the Royal Society, a post that was later accompanied by a stipend of fifty pounds a year, although there is some evidence to suggest that he rarely actually got paid. This post involved much organizational work for the society, but it also placed Halley in the thick of its debates. Around this time, wanting to confirm some of his observations on comets, Halley went to visit Newton at Cambridge. During their discussions, Newton claimed to have solved the elliptical problem, asserting that the elliptical shape of planetary orbits was a result of the inverse square law of attraction, which states that bodies are attracted to one another in proportion of the inverse square of their distance from one another. Newton said, however, that he had mislaid the proof, so Halley was not totally convinced.

On Halley’s second visit, Newton successfully produced a nine-page paper explaining the elliptical orbits of the planets, and Halley, recognizing the overwhelming importance of Newton’s work, persuaded him to publish it. Through Halley’s offices, Newton published first a short tract, De motu corporum in gyrum (1684; on the motion of bodies in an orbit), which demonstrated Kepler’s laws of planetary motion, and then his famous book Philosophiae Naturalis Principia Mathematica (1687; Mathematical Principles of Natural Philosophy , 1729), in which he elaborated his three laws of mechanics and his theory of gravity.

This work was, perhaps, the most important scientific work to be published in the century and, throughout, Halley was Newton’s friend, confidant, editor, and publisher, encouraging him to continue, adding the occasional helpful comment to the manuscript, and even finally paying for its publication. He also had the difficult and diplomatic task of mediating between Newton and Hooke, who were rivals, the latter claiming that Newton had not credited his contribution to the discovery of the inverse square law. Halley’s involvement in this dispute made Hooke his enemy too, and Hooke tried to remove him from his post of clerk to the Royal Society. Halley’s efficiency and popularity won the day, however, and Hooke’s motion was defeated.

During this period of his life, Halley, who had numerous diverse interests, wrote a paper trying to explain the causes of the biblical Flood. This paper was to have disastrous consequences for his career. He argued that the Flood had occurred for natural, not miraculous reasons, possibly from a close encounter with a comet. (It is interesting to note that speculation about the effects of comets on the Earth has flourished ever since.) The result of Halley’s reasoning was to place the date of the Flood somewhat earlier than the accepted orthodoxy of 4004 b.c.e.

Halley’s theory of the Flood offended his more religious colleagues, and rumors abounded that Halley might be a skeptic or, worse still, an agnostic. In 1691, a vacancy opened for the Savilian Chair of Astronomy at Oxford. Were it not for this paper and the question concerning Halley’s religious beliefs, he would certainly have been appointed. Flamsteed, however, argued vehemently against him, and not even Newton came to his protégé’s defense. Later, in 1694, when he finally presented the offending paper to the Royal Society, he added the explanation that he was not actually referring to the Flood itself but speculating on what might have happened given the proper circumstances—thus mitigating some of the damage to his reputation.

Although Halley is best known for his work in astronomy, he made contributions in a number of other areas during his life, perhaps motivated by his persistent lack of money. He was interested in nautical problems, designing various practical instruments: a prototype diving bell, a device for measuring the path of a ship, and another device for measuring the rate of evaporation of seawater. This latter device had consequences for another interest of his, chronology. Indeed, it led to some of his conclusions about the date of the Flood.

Between 1696 and 1698, Halley’s career took another turn. He became the deputy comptroller of the Royal Mint at Chester, a post offered him by Newton, who was then the warden of the Mint. (At the time, there was much trouble with “clipped” gold and silver coins, and scientists were being used to supervise the minting.) Administration did not prove to be one of Halley’s many talents, however, and Newton found himself having to defend his friend against the Lord’s Commissioners. In 1698, Halley set out on another expedition, this time to the South Seas to study the magnetic variations of the earth’s compass. The journey was abandoned (with the ship’s first lieutenant facing a court-martial on their return), but Halley tried again a year later with more success. He also went on a secret mission in 1701, about which little is known, traveling to France for the Admiralty on the pretext of yet another scientific expedition.

While Halley’s accomplishments were many, the achievements for which he is best known are in the field of astronomy, particularly regarding the orbits of comets. This was a field on which he had already begun detailed work when he first met Newton. By 1695, he had undergone a thorough search of historical records on the subject, examining the figures with scrupulous attention. Recognizing that comets, too, were affected by the gravitational influence of the planets (following Newton’s work), Halley calculated their possible orbits from the available data. That led him to disagree with Newton, who, in book 3 of Mathematical Principles of Natural Philosophy, had argued that comets’ orbits should be parabolic. Halley concluded that they must, in fact, be elliptical like the planets themselves.

In 1703, Halley became a member of the Council of the Royal Society in recognition of his work, and in the same year, he was appointed to the Savilian Chair of Geometry at Oxford, previous doubts about his religion being now forgotten. Two years later, he published Astronomie cometicae synopsis (1705; synopsis of cometary astronomy), in which he outlined his theory of elliptical orbits for comets and asserted that the particular comet seen in 1682 would, as part of its periodic cycle, return in 1758. Although he did not live long enough to test his hypothesis, when the comet did come into view in 1759 (Halley made a minor miscalculation), it was seen not only as a verification of Halley’s prediction but also as a major confirmation of the truth of Newton’s mechanics. The comet was named for Halley. In 1719, on Flamsteed’s death, Halley succeeded to the post of astronomer royal, a position he held until his death in 1742.

Significance

Halley lived at a time when the old theories of the structure of the universe, which were still based on the teachings of Aristotle, were being overturned. Experimentally, Galileo and Kepler had led the way, but it took the work of Newton to provide a theoretical underpinning to it all. Halley, in publishing Newton’s work, had been largely responsible for bringing it to the attention of scientists and the public. Newton’s theories turned the scientific world upside down, causing debate, discussion, and disagreement for nearly a century after their publication. One of the major triumphs of the new theories, helping eventually to bring about their universal acceptance, was the reappearance of Halley’s comet, which he had predicted using Newton’s work and his own observations. Halley’s meticulous recording of observational detail and his ready grasp of contemporary theories had enabled him to become the champion of Newtonian science. In this way, he was central to one of the most exciting periods of scientific history.

Bibliography

Armitage, Angus. Edmond Halley. Camden, N.J.: Thomas Nelson and Sons, 1966. A detailed historical evaluation of Halley’s scientific research, mainly based on the papers he contributed to Philosophical Transactions, with relevant biographical information. Illustrated with plates and figures.

Calder, Nigel. Comets: Speculation and Discovery. New York: Dover, 1994. A popular account of the science, facts, and legends related to Halley’s comet, and the people involved in its discovery and observation. Originally published in 1981 as The Comet Is Coming! The Feverish Legacy of Mr. Halley.

Cook, Alan. Edmond Halley: Charting the Heavens and the Seas. New York: Oxford University Press, 1998. A full-length biography drawing upon recently acquired information to discuss Halley’s life and his contributions to science.

Halley, Edmond. Correspondence and Papers of Edmond Halley. Edited by Eugene Fairfield MacPike. Oxford, England: Clarendon Press, 1932. Reprint. New York: Arno Press, 1975. An edited collection of Halley’s surviving papers and letters, with a memoir of his life by one of his contemporaries, and the “Éloge” by d’Ortous de Mairan. The best, although necessarily incomplete, primary source for students of Halley.

Lancaster Brown, Peter. Halley and His Comet. Poole, Dorset, England: Blandford Press, 1985. Occasioned by the anticipated appearance of Halley’s comet in 1986, a modern reappraisal of Halley’s life and work, its relevance to the origins of life on Earth, and its significance to the space age. Highly informative for specialists and lay readers.

Newton, Sir Isaac. A Dissertation on Comets. London: c. 1750. Describes the mechanical principles of the motions of planets, using Newton’s new theory of gravity, from which Halley developed his own theory that comets travel in ellipses and will therefore return.

‗‗‗‗‗‗‗. The Mathematical Principles of Natural Philosophy. Translated by Andrew Motte. London: B. Motte, 1729. Originally published by Halley, who, recognizing the importance of Newton’s theories of gravity and motion, persuaded him to put it into book form. Motte’s translation remains the standard text.

Thrower, Norman J. W., ed. Standing on the Shoulders of Giants: A Longer View of Newton and Halley. Berkeley: University of California Press, 1990. A collection of essays by astronomers, historians of science, and other writers that re-examine the professional relationship of Newton and Halley, describing their influence upon each other and on subsequent generations of scientists.