Isaac Newton's apple tree near Grantham, Lincolnshire is fenced off | Daily Mail Online comments An apple once fell from a tree, hit someone's head and helped discover gravity. But the leafy canopy from under which Sir Isaac Newton was to form his theory on gravitational force, will soon no longer be enjoyed as it once was. The plethora of tourists who perennially visit the special spot in Sir Isaac's childhood home are steadily damaging the tree's roots. In order to protect its longevity, a willow fencing has been erected around it. Safety barrier: A new willow barrier has been put up around the most famous tree in science - the apple tree which inspired Newton's theory of gravity 400-year-old tree: A pencil sketch of Newton's apple tree as it was in 1840 It means visitors to the 17th century Woolsthorpe Manor, near Grantham, Lincolnshire, will no longer be able to sit under its branches as Newton was said to have been doing in 1665 when ‘the notion of gravitation came to mind’.

The National Trust, which owns the small manor house where Newton was born in 1642, said the 2ft-high fence was designed to preserve the tree, not exclude visitors. Famous physicist: Sir Isaac Newton was inspired by the apple tree at Woolsthorpe Manor Official Ann Moynihan said there had been no damage so far but warned that there could soon be a problem. RELATED ARTICLES Share this article Share ‘Visitor numbers have gone up by around 50 per cent, to 33,000 a year in three years. The more people who visit, the more the soil will become compacted around the tree and over the roots.’ She said the tree – which re-rooted itself in 1820 after being blown down in a storm and grew back in an ‘inverted S-shape’ – was already difficult to get close to because of its shape. Mrs Moynihan denied the fence, which runs around the tree’s ‘root run’, was a response to any health and safety concerns. ‘People have always been free to walk around the apple orchard unescorted,’ she added.

‘We just want to preserve the tree for another 400 years if we can.’ She said visitors will still be able to take apples from the tree. Visitor and history graduate Chris Gwyther, 37, said: ‘I suppose it is a pity that you can’t sit under the tree like Newton. ‘But you can still see it and the tree is 400-years-old, it needs saving for the future.’ The tree is of the rare Flower of Kent variety, a green cooking apple. It stands in the front garden of the property and is visible from what was Newton’s bedroom window. Newton left no account confirming he had been inspired by a falling apple. The story appeared in a book by French philosopher Voltaire published in 1727, the year Newton died at the age of 84. The best physicist of his generation Sir Isaac Newton's work on universal gravitation and the three laws of motion are some of the most influential scientific theories every developed. But born prematurely in 1643, the well-known scientist was not expected to survive infancy.

By the age of 26 he had become a professor of maths at Cambridge University before explaining gravity in Mathematical Principles of Natural Philosophy, published in 1687. Two years later, he became the Cambridge University member of Parliament and was later knighted. He died in 1727 aged 84 and was buried in Westminster Abbey. Last year, a piece of the famous apple tree from his family home was sent into space - defying gravity - on Space Shuttle Atlantis, nearly 350 years after he wrote his influential work. The apple didn't fall on Sir Isaac Newton It is a popular misconception that the apple fell on Sir Isaac Newton's head as he sat underneath the tree. Although Sir Isaac developed his theory after observing the fruit falling, there was no 'eureka' moment. He realised if an apple falls from a tree then gravity may extend even further - possibly even into space. He realised that gravity was the force of attraction between two objects and that an object with more mass exerted a greater force or pull. This meant the giant mass of Earth pulled objects towards it, which was why the apple fell down instead of floating in the air.

He is believed to have developed the theory between 1665 and 1666. Did an Inspirational Apple Really Fall on Newton's Head? Did an Inspirational Apple Really Fall on Newton's Head? In grade school you probably learned Newton’s apple story around the time you learned that George Washington chopped down a cherry tree , that people in Columbus’ time thought that the world was flat , or that the Pilgrims celebrated the first Thanksgiving in America and invited the Native Americans to join them . Advertisement Since literally none of the latter three stories here are true (follow the preceding links for full details), you probably have your doubts about whether Newton actually sat under an apple tree and had something of a “eureka” moment concerning gravity. It might surprise you to learn, then, that your teachers got one of these stories (partially) correct. Newton was indeed sitting under an apple tree when he had his so-called “eureka” moment on how gravity worked. Advertisement Although, it took him over two decades more to develop the fully-fledged theory of “universal gravitation”, first published in his Philosophiæ Naturalis Principia Mathematica on July 5, 1687.

He also didn’t complete it without some ideas others had already come up with, such as Christopher Wren, Robert Hooke, and Edmond Halley ( who Halley’s comet is named after ); though Newton claims particularly Hooke, who corresponded heavily with Newton on gravity, and his ideas had little real bearing on his work, other than simply to inspire him to continue working on the problem. As Newton stated when Hooke accused Newton of plagiarizing his work: Yet am I not beholden to him for any light into that business but only for the diversion he gave me from my other studies to think on these things & for his dogmaticalness in writing as if he had found the motion in the Ellipsis, which inclined me to try it… So perhaps “eureka” conveys much too strong of a leap. From accounts, he was more just put on the correct path while musing under the tree. Sponsored Further, it would seem that the apple didn’t fall directly on his head- at least there is no documented evidence of this. But if you discount the notion that he near instantly fleshed out his universal theory and the “fell on his head” bit, the common story is pretty accurate.

One of the best sources we have for the “apple falling on Newton’s head” anecdote is a manuscript written by Newton’s friend William Stukeley. He published Memoirs of Sir Isaac Newton’s Life in 1752, becoming one of Newton’s first biographers. Many of the incidences described in the book were recorded much earlier than 1752, including the “apple” story which was first documented in 1726, the year Newton died, and then again a year later by Voltaire in his Epic Poetry . $23 Stukeley’s account is as follows: Advertisement Advertisement After dinner, the weather being warm, we went into the garden, & drank tea under the shade of some appletrees, only he, & myself. amidst other discourse, he told me, he was just in the same situation, as when formerly, the notion of gravitation came into his mind. “Why should that apple always descend perpendicularly to the ground,” thought he to him self: occasion’d by the fall of an apple, as he sat in a contemplative mood: “Why should it not go sideways, or upwards? but constantly to the earths centre?

Assuredly, the reason is, that the earth draws it. There must be a drawing power in matter. & the sum of the drawing power in the matter of the earth must be in the earths centre, not in any side of the earth. therefore dos this apple fall perpendicularly, or toward the centre. If matter thus draws matter; it must be in proportion of its quantity. Therefore the apple draws the earth, as well as the earth draws the apple. John Conduitt, Newton’s assistant and the husband of his niece, told pretty much the same story. Newton lived with the pair in his later years and doted upon their daughter.

When writing about Newton, Conduitt said: In the year he retired again from Cambridge on account of the plague to his mother in Lincolnshire & whilst he was musing in a garden it came into his thought that the same power of gravity (which made an apple fall from the tree to the ground) was not limited to a certain distance from the earth but must extend much farther than was usually thought – Why not as high as the Moon said he to himself & if so that must influence her motion & perhaps retain her in her orbit, whereupon he fell a calculating what would be the effect of that supposition but being absent from books & taking the common estimate in use among Geographers & our sea men before Norwood had measured the earth, that 60 English miles were contained in one degree of latitude his computation did not agree with his Theory & inclined him then to entertain a notion that together with the power of gravity there might be a mixture of that force which the moon would have if it was carried along in a vortex, but when the Tract of Picard of the measure of the earth came out shewing that a degree was about 69.12 English miles He began his calculation a new & found it perfectly agreeable to his Theory.

The “year [Newton] retired again from Cambridge” was 1666, which means Stukeley’s recording of the event took place some 60 years after it happened. However, both Stukeley and Conduitt, among others, appear to have independently heard the story directly from Newton himself, making it reasonable to believe a falling apple was, indeed, the source of Newton’s first significant musings over how gravity works. Advertisement There are many different places which claim to be the home of the apple tree that inspired Newton’s theory, but the most likely one—given the accounts—is located at his family home of Woolsthorpe Manor near Grantham, UK. And, yes, there is an apple tree there today that is thought to be the apple tree in question, though it has re-rooted in the interim after being knocked over in a storm in 1890. Now around 400 years old, the tree and the property are protected by the National Trust. If you’re curious, the tree is a Flower of Kent, which doesn’t produce very good apples for eating by today’s standards, though they are considered good cooking apples.

Further, the apples in question are green, not red as is often depicted in Isaac Newton/apple images. Advertisement Advertisement You’ll note, of course, that Stukeley above stated there was more than one apple tree there at the time; so whether this remaining one is “the” apple tree is a question can’t be definitively answered until someone invents a machine that can take us back in time to observe the event. That being said, Dr Richard Keesing from the Department of Physics at the University of York makes a pretty good case for why it probably is the correct tree . Despite this uncertainty, there are a many trees that have been started as grafts from the Woolsthorpe tree, including one at Trinity College in Cambridge which sits beneath the window of the room Newton used when studying there.

If you liked this article, you might also enjoy: Advertisement When Columbus Used His Knowledge of a Lunar Eclipse to Trick Natives Into Giving Him Supplies Bonus Facts: Astronomer Alexis Clairaut in 1727 commented on Hooke’s accusations that Newton stole Hooke’s work, summing up the situation nicely: “One must not think that this idea … of Hooke diminishes Newton’s glory… the example of Hooke [serves] to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated.” Essentially, Hooke guessed at a notion that Newton was able to prove. Newton himself never chose to make an official guess at what actually was the underlying mechanism of gravity.

In fact, while he noted “It is enough that gravity does really exist and acts according to the laws I have explained, and that it abundantly serves to account for all the motions of celestial bodies,” he also stated “That one body may act upon another at a distance through a vacuum without the mediation of anything else, by and through which their action and force may be conveyed from one another, is to me so great an absurdity that, I believe, no man who has in philosophic matters a competent faculty of thinking could ever fall into it.” Besides the above references to who Newton told the “apple tree” story to, two others also gave an account of him telling the story to them: Catherine Barton (his niece) and Christopher Dawson (a student at Cambridge). It isn’t clear whether Voltaire heard the “apple” story from Newton himself or if he was told it by a mutual friend or found out about it in some other manner. That said, the pair were friends or at least acquaintances, depending on your definition of “friends”. Voltaire was even present at Newton’s funeral. In 1976, Apple Computers briefly used a logo that featured Sir Isaac Newton sitting beneath an apple tree.

It was designed by Ronald Wayne, a lesser-known co-founder of the company. Apple later changed the logo to the more recognizable rainbow apple with the bite taken out of it. Newton has been commemorated in many different ways. Perhaps one of the larger monuments to his genius is a statue by Eduardo Paolozzi which stands near the British Library in London. The statue is based on an etching of Newton by William Blake. William Stukeley, Newton’s biographer, had quite the resume himself. In addition to being a doctor, he had a key interest in historical monuments and is perhaps best known for his excavation of Stonehenge. He was the first person to recognize the alignment of Stonehenge on solstices and attributed the iconic landmark to the druids. He later became a vicar, had a keen interest in Robin Hood, and wrote music for the flute. Newton was buried in Westminster Abbey. Not far down the nave, John Conduitt was also buried.

According to an inscription, Conduitt “wished his remains to be placed opposite this spot, near to the ashes of the great Newton, to whom he was linked by ties of affinity.” Mercury was found in Newton’s hair when it was examined after his death, likely a result of his experiments in alchemy. Newton was the second scientist to be knighted, though it’s thought he was granted knighthood for political reasons rather than his achievements. He was knighted in April 1705, over 100 years after the first knighted scientist, Sir Francis Bacon, was given the honour in 1603. The value of “G” in Newton’s famous “universal gravity” equation wasn’t accurately determined until 71 years after Newton’s death and 111 years after he published the equation. Emily Upton writes for the wildly popular interesting fact website TodayIFoundOut.com . To subscribe to Today I Found Out's “Daily Knowledge” newsletter, click here or like them on Facebook here . You can also check 'em out on YouTube . Advertisement Advertisement This post has been republished with permission from TodayIFoundOut.com . Image by MShades under Creative Commons license.

Gear from Kinja Deals The core of truth behind Sir Isaac Newton's apple | The Independent Monday 18 January 2010 00:00 BST Click to follow The Independent Online It is one of the most famous anecdotes in the history of science. The young Isaac Newton is sitting in his garden when an apple falls on his head and, in a stroke of brilliant insight, he suddenly comes up with his theory of gravity. The story is almost certainly embellished, both by Newton and the generations of storytellers who came after him. But from today anyone with access to the internet can see for themselves the first-hand account of how a falling apple inspired the understanding of gravitational force. The Royal Society in London is making available in digital form the key original manuscript that describes how Newton devised his theory of gravity after witnessing an apple falling from a tree in his mother's garden in Lincolnshire, although there is no evidence to suggest that it hit him on the head. It was 1666, and the plague had closed many public buildings and meetings.

Newton had to abandon Cambridge for Woolsthorpe Manor, near Grantham in Lincolnshire, the modest house where he was born, to contemplate the stellar problems he had been pursuing at the university. He was particularly obsessed by the orbit of the Moon around the Earth, and eventually reasoned that the influence of gravity must extend over vast distances. After seeing how apples always fall straight to the ground, he spent several years working on the mathematics showing that the force of gravity decreased as the inverse square of the distance. But what evidence is there that Newton was really inspired by a falling apple? He left no written account suggesting this, although there were other documents suggesting that he had spoken to others about it when he was an old man. Historians point to the one particular account written by one of Newton's younger contemporaries, an antiquarian and proto-archaeologist called William Stukeley, who also wrote the first biography of Britain's greatest scientist, entitled Memoirs of Sir Isaac Newton's Life. Stukeley was also born in Lincolnshire, and used this connection to befriend the notoriously cantankerous Newton. Stukeley spent some time in conversation with the older man, and the pair met regularly as fellows of the Royal Society, and talked together.

On one particular occasion in 1726, Stukeley and Newton spent the evening dining in London. "After dinner, the weather being warm, we went into the garden & drank thea under the shade of some apple tree; only he & myself," Stukeley wrote in the meticulously handwritten manuscript released by the Royal Society. "Amid other discourse, he told me, he was just in the same situation, as when formerly the notion of gravitation came into his mind. Why sh[oul]d that apple always descend perpendicularly to the ground, thought he to himself; occasion'd by the fall of an apple, as he sat in contemplative mood. "Why sh[oul]d it not go sideways, or upwards? But constantly to the Earth's centre? Assuredly the reason is, that the Earth draws it. There must be a drawing power in matter. And the sum of the drawing power in the matter of the Earth must be in the Earth's centre, not in any side of the Earth. "Therefore does this apple fall perpendicularly or towards the centre? If matter thus draws matter; it must be proportion of its quantity.

Therefore the apple draws the Earth, as well as the Earth draws the apple." This is the most detailed account of the apple anecdote, but it is not the only one from Newton's day. He had also used it to entertain John Conduitt, the husband of Newton's niece and his assistant at the Royal Mint, which Newton had run in his later years. Conduitt wrote: "In the year 1666 he retired again from Cambridge to his mother in Lincolnshire. Whilst he was pensively meandering in a garden it came into his thought that the power of gravity (which brought an apple from a tree to the ground) was not limited to a certain distance from Earth, but that this power must extend much further than was usually thought. "Why not as high as the Moon said he to himself & if so, that must influence her motion & perhaps retain her orbit, whereupon he fell a calculating what would be the effect of that supposition." Both accounts of the apple incident were recalled by Newton some 50 years later. Did it really happen, or was it a story that Newton embellished or even invented?

"Newton cleverly honed this anecdote over time," said Keith Moore, head of archives at the Royal Society. "The story was certainly true, but let's say it got better with the telling." The story of the apple fitted with the idea of an Earth-shaped object being attracted to the Earth. It also had a resonance with the Biblical account of the tree of knowledge, and Newton was known to have extreme religious views, Mr Moore said. At Woolsthorpe Manor, now owned by the National Trust, the house steward, Margaret Winn, said that the same apple tree, a cooking variety known as Flower of Kent, still grows to the front of the house, in sight of Newton's bedroom window. "He did tell the story as an old man but you do wonder whether it really happened," said Ms Winn, who has cooked with the apples. But even if the tale was the fanciful imaginings of an old man, the story of the falling apple has gone down in history as the second-greatest "eureka moment" in science, after Archimedes discovered how to work out the volume of objects while he was in the bath.

View the Stukeley manuscript at Eureka moments: How they 'got it' *Archimedes is thought to have been the first scientist to shout out the Greek word "Eureka!" to mark a breakthrough, when he discovered his principle of buoyancy. Roman writer Vitruvius wrote that Archimedes was taking a bath when he realised that when he stepped into his tub, his body mass displaced a certain weight of water. The scientist is said to have jumped out of the bath and run naked through the streets of Syracuse in Sicily shouting: "Eureka, eureka!" ("I have found it!"). Doubt has since been cast on the authenticity of this story, given that Vitruvius was writing nearly 200 years later. *Otto Loewi, the German physiologist, spent 17 years trying to come up with definitive proof that nerve impulses were transmitted chemically, and was finally struck by inspiration one night when he had a dream showing him how to carry out a key experiment using a frog's heart.

He immediately went to his laboratory to conduct the experiment, noting that electrical stimulation of a frog's vagus nerve released a chemical, now known to be the neurotransmitter acetylcholine, which controlled the heart rate. *Although it is commonly thought that Charles Darwin came up with his theory of natural selection while on the Galapagos Islands in 1835, he only started to believe in evolution after he returned to England. Instead of being struck by a single "Eureka moment", the scientist spent two decades pondering his observations, finally presenting his controversial theory in his 1859 book On the Origin of Species. Sofia Mitra-Thakur More about: Newton's Apple Tree - Physics, The University of York A Brief History of Isaac Newton's Apple Tree Growing in a courtyard garden in the Physics Department here in the University of York we have a grafted cutting from an ancient apple tree which still survives in Newton's garden at Woolsthorpe Manor, his birthplace in Lincolnshire. This is the tree from which it is reputed that Newton saw an apple fall in the late summer of 1666 and which caused him to speculate upon the nature of gravitation.

Our tree was given to us by Kew Gardens in 1976. The account of Isaac Newton's discovering the principle of universal gravitation by observing the fall of an apple is very well known and usually dismissed as apocryphal. However little can be further from the truth for Newton gave this account of his discovery to several acquaintances which include Voltaire (French philosopher and essayist), John Conduitt (his assistant at the Royal Mint) Catherine Barton (his niece) William Stewkeley (friend and antiquarian), Christopher Dawson (a student at Cambridge) amongst others. The first written account appears in notes on Newton's life collected by John Conduitt in 1726 the year of Newton's death. It states that; he first thought of his system of gravitation which he hit upon by observing an apple fall from a tree , The incident occurring in the late summer of 1666. In other accounts it is stated that Newton was sitting in his garden at Woolsthorpe Manor near Grantham in Lincolnshire when the incident occurred.

The first account of their being a specific tree in his garden from which Newton saw the apple fall appears in the book ‘A History of the Town and Soak of Grantham’ by Edmund Turnor FRS (1806) in which there appears the footnote on p160: The tree is still remaining and is showed to strangers . His brother the, Rev. Charles Turnor, drew the accompanying picture of the tree in 1820 showing its position with respect to the manor house. Although Newton did not specify from which tree he observed the apple fall it turned out that it was the only apple tree growing in his garden and thus it selected itself. This was first mentioned by Sir David Brewster when he visited the house in 1830, the account of which was given by George Forbes (Professor of Physics University of Glasgow) The tree had been cared for since the 1750’s by generations of the Woolerton family, who were tenant farmers who lived in the house from 1733 to 1947. Despite all their efforts to prop the aged tree up, it blew down in a storm in 1816.

Some branches were removed but the major portion of the tree was left and re-rooted. The surprising fact is that this tree is still growing at Woolsthorpe Manor today and now must be over 350 years old. Isaac Newton’s Apple Tree is now on its third set of roots but still provides a good crop of apples each summer. Its appearance in 1998 is shown in the above photograph. Our Newton Apple Tree Pedigree: The apple is the extremely rare variety ‘Flower of Kent’ which was first mentioned in the fifteenth century. The tree we have growing here in The Physics Department was provided for us by Kew Gardens in 1976. It came from the Cambridge Botanical Gardens who obtained it from the Fruit Research Station at East Malling in Kent. They obtained their stock from a tree at Belton Park in Lincolnshire in the 1930’s which had been propagated there from Newton’s garden at Woolsthorpe Manor by the Rev Charles Turnor about the year 1820.

Dr Richard Keesing, Department of Physics, University of York Isaac Newton's Life | Isaac Newton Institute for Mathematical Sciences Isaac Newton Institute for Mathematical Sciences Special thanks to the Microsoft Corporation for their contribution to our site. The following information came from Microsoft Encarta. I INTRODUCTION Newton, Sir Isaac (1642-1727), mathematician and physicist, one of the foremost scientific intellects of all time. Born at Woolsthorpe, near Grantham in Lincolnshire, where he attended school, he entered Cambridge University in 1661; he was elected a Fellow of Trinity College in 1667, and Lucasian Professor of Mathematics in 1669. He remained at the university, lecturing in most years, until 1696. Of these Cambridge years, in which Newton was at the height of his creative power, he singled out 1665-1666 (spent largely in Lincolnshire because of plague in Cambridge) as "the prime of my age for invention".

During two to three years of intense mental effort he prepared Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) commonly known as the Principia, although this was not published until 1687. As a firm opponent of the attempt by King James II to make the universities into Catholic institutions, Newton was elected Member of Parliament for the University of Cambridge to the Convention Parliament of 1689, and sat again in 1701-1702. Meanwhile, in 1696 he had moved to London as Warden of the Royal Mint. He became Master of the Mint in 1699, an office he retained to his death. He was elected a Fellow of the Royal Society of London in 1671, and in 1703 he became President, being annually re-elected for the rest of his life. His major work, Opticks, appeared the next year; he was knighted in Cambridge in 1705. As Newtonian science became increasingly accepted on the Continent, and especially after a general peace was restored in 1714, following the War of the Spanish Succession, Newton became the most highly esteemed natural philosopher in Europe.

His last decades were passed in revising his major works, polishing his studies of ancient history, and defending himself against critics, as well as carrying out his official duties. Newton was modest, diffident, and a man of simple tastes. He was angered by criticism or opposition, and harboured resentment; he was harsh towards enemies but generous to friends. In government, and at the Royal Society, he proved an able administrator. He never married and lived modestly, but was buried with great pomp in Westminster Abbey. Newton has been regarded for almost 300 years as the founding examplar of modern physical science, his achievements in experimental investigation being as innovative as those in mathematical research. With equal, if not greater, energy and originality he also plunged into chemistry, the early history of Western civilization, and theology; among his special studies was an investigation of the form and dimensions, as described in the Bible, of Solomon's Temple in Jerusalem. II OPTICS In 1664, while still a student, Newton read recent work on optics and light by the English physicists Robert Boyle and Robert Hooke; he also studied both the mathematics and the physics of the French philosopher and scientist René Descartes.

He investigated the refraction of light by a glass prism; developing over a few years a series of increasingly elaborate, refined, and exact experiments, Newton discovered measurable, mathematical patterns in the phenomenon of colour. He found white light to be a mixture of infinitely varied coloured rays (manifest in the rainbow and the spectrum), each ray definable by the angle through which it is refracted on entering or leaving a given transparent medium. He correlated this notion with his study of the interference colours of thin films (for example, of oil on water, or soap bubbles), using a simple technique of extreme acuity to measure the thickness of such films. He held that light consisted of streams of minute particles. From his experiments he could infer the magnitudes of the transparent "corpuscles" forming the surfaces of bodies, which, according to their dimensions, so interacted with white light as to reflect, selectively, the different observed colours of those surfaces. The roots of these unconventional ideas were with Newton by about 1668; when first expressed (tersely and partially) in public in 1672 and 1675, they provoked hostile criticism, mainly because colours were thought to be modified forms of homogeneous white light.

Doubts, and Newton's rejoinders, were printed in the learned journals. Notably, the scepticism of Christiaan Huygens and the failure of the French physicist Edmé Mariotte to duplicate Newton's refraction experiments in 1681 set scientists on the Continent against him for a generation. The publication of Opticks, largely written by 1692, was delayed by Newton until the critics were dead. The book was still imperfect: the colours of diffraction defeated Newton. Nevertheless, Opticks established itself, from about 1715, as a model of the interweaving of theory with quantitative experimentation. III MATHEMATICS In mathematics too, early brilliance appeared in Newton's student notes. He may have learnt geometry at school, though he always spoke of himself as self-taught; certainly he advanced through studying the writings of his compatriots William Oughtred and John Wallis, and of Descartes and the Dutch school. Newton made contributions to all branches of mathematics then studied, but is especially famous for his solutions to the contemporary problems in analytical geometry of drawing tangents to curves (differentiation) and defining areas bounded by curves (integration).

Not only did Newton discover that these problems were inverse to each other, but he discovered general methods of resolving problems of curvature, embraced in his "method of fluxions" and "inverse method of fluxions", respectively equivalent to Leibniz's later differential and integral calculus. Newton used the term "fluxion" (from Latin meaning "flow") because he imagined a quantity "flowing" from one magnitude to another. Fluxions were expressed algebraically, as Leibniz's differentials were, but Newton made extensive use also (especially in the Principia) of analogous geometrical arguments. Late in life, Newton expressed regret for the algebraic style of recent mathematical progress, preferring the geometrical method of the Classical Greeks, which he regarded as clearer and more rigorous. Newton's work on pure mathematics was virtually hidden from all but his correspondents until 1704, when he published, with Opticks, a tract on the quadrature of curves (integration) and another on the classification of the cubic curves. His Cambridge lectures, delivered from about 1673 to 1683, were published in 1707.

The Calculus Priority Dispute Newton had the essence of the methods of fluxions by 1666. The first to become known, privately, to other mathematicians, in 1668, was his method of integration by infinite series. In Paris in 1675 Gottfried Wilhelm Leibniz independently evolved the first ideas of his differential calculus, outlined to Newton in 1677. Newton had already described some of his mathematical discoveries to Leibniz, not including his method of fluxions. In 1684 Leibniz published his first paper on calculus; a small group of mathematicians took up his ideas. In the 1690s Newton's friends proclaimed the priority of Newton's methods of fluxions. Supporters of Leibniz asserted that he had communicated the differential method to Newton, although Leibniz had claimed no such thing. Newtonians then asserted, rightly, that Leibniz had seen papers of Newton's during a London visit in 1676; in reality, Leibniz had taken no notice of material on fluxions.

A violent dispute sprang up, part public, part private, extended by Leibniz to attacks on Newton's theory of gravitation and his ideas about God and creation; it was not ended even by Leibniz's death in 1716. The dispute delayed the reception of Newtonian science on the Continent, and dissuaded British mathematicians from sharing the researches of Continental colleagues for a century. IV MECHANICS AND GRAVITATION According to the well-known story, it was on seeing an apple fall in his orchard at some time during 1665 or 1666 that Newton conceived that the same force governed the motion of the Moon and the apple. He calculated the force needed to hold the Moon in its orbit, as compared with the force pulling an object to the ground. He also calculated the centripetal force needed to hold a stone in a sling, and the relation between the length of a pendulum and the time of its swing. These early explorations were not soon exploited by Newton, though he studied astronomy and the problems of planetary motion.

Correspondence with Hooke (1679-1680) redirected Newton to the problem of the path of a body subjected to a centrally directed force that varies as the inverse square of the distance; he determined it to be an ellipse, so informing Edmond Halley in August 1684. Halley's interest led Newton to demonstrate the relationship afresh, to compose a brief tract on mechanics, and finally to write the Principia. Book I of the Principia states the foundations of the science of mechanics, developing upon them the mathematics of orbital motion round centres of force. Newton identified gravitation as the fundamental force controlling the motions of the celestial bodies. He never found its cause. To contemporaries who found the idea of attractions across empty space unintelligible, he conceded that they might prove to be caused by the impacts of unseen particles. Book II inaugurates the theory of fluids: Newton solves problems of fluids in movement and of motion through fluids. From the density of air he calculated the speed of sound waves. Book III shows the law of gravitation at work in the universe: Newton demonstrates it from the revolutions of the six known planets, including the Earth, and their satellites.

However, he could never quite perfect the difficult theory of the Moon's motion. Comets were shown to obey the same law; in later editions, Newton added conjectures on the possibility of their return. He calculated the relative masses of heavenly bodies from their gravitational forces, and the oblateness of Earth and Jupiter, already observed. He explained tidal ebb and flow and the precession of the equinoxes from the forces exerted by the Sun and Moon. All this was done by exact computation. Newton's work in mechanics was accepted at once in Britain, and universally after half a century. Since then it has been ranked among humanity's greatest achievements in abstract thought. It was extended and perfected by others, notably Pierre Simon de Laplace, without changing its basis and it survived into the late 19th century before it began to show signs of failing. See Quantum Theory; Relativity. V ALCHEMY AND CHEMISTRY Newton left a mass of manuscripts on the subjects of alchemy and chemistry, then closely related topics. Most of these were extracts from books, bibliographies, dictionaries, and so on, but a few are original.

He began intensive experimentation in 1669, continuing till he left Cambridge, seeking to unravel the meaning that he hoped was hidden in alchemical obscurity and mysticism. He sought understanding of the nature and structure of all matter, formed from the "solid, massy, hard, impenetrable, movable particles" that he believed God had created. Most importantly in the "Queries" appended to "Opticks" and in the essay "On the Nature of Acids" (1710), Newton published an incomplete theory of chemical force, concealing his exploration of the alchemists, which became known a century after his death. VI HISTORICAL AND CHRONOLOGICAL STUDIES Newton owned more books on humanistic learning than on mathematics and science; all his life he studied them deeply. His unpublished "classical scholia"explanatory notes intended for use in a future edition of the Principiareveal his knowledge of pre-Socratic philosophy; he read the Fathers of the Church even more deeply. Newton sought to reconcile Greek mythology and record with the Bible, considered the prime authority on the early history of mankind.

In his work on chronology he undertook to make Jewish and pagan dates compatible, and to fix them absolutely from an astronomical argument about the earliest constellation figures devised by the Greeks. He put the fall of Troy at 904 BC, about 500 years later than other scholars; this was not well received. VII RELIGIOUS CONVICTIONS AND PERSONALITY Newton also wrote on Judaeo-Christian prophecy, whose decipherment was essential, he thought, to the understanding of God. His book on the subject, which was reprinted well into the Victorian Age, represented lifelong study. Its message was that Christianity went astray in the 4th century AD, when the first Council of Nicaea propounded erroneous doctrines of the nature of Christ. The full extent of Newton's unorthodoxy was recognized only in the present century: but although a critic of accepted Trinitarian dogmas and the Council of Nicaea, he possessed a deep religious sense, venerated the Bible and accepted its account of creation. In late editions of his scientific works he expressed a strong sense of God's providential role in nature.

VIII PUBLICATIONS Newton published an edition of Geographia generalis by the German geographer Varenius in 1672. His own letters on optics appeared in print from 1672 to 1676. Then he published nothing until the Principia (published in Latin in 1687; revised in 1713 and 1726; and translated into English in 1729). This was followed by Opticks in 1704; a revised edition in Latin appeared in 1706. Posthumously published writings include The Chronology of Ancient Kingdoms Amended (1728), The System of the World (1728), the first draft of Book III of the Principia, and Observations upon the Prophecies of Daniel and the Apocalypse of St John (1733). Contributed By: Alfred Rupert Hall "Sir Isaac Newton" Microsoft® Encarta®. Copyright © 1998 Microsoft Corporation. Isaac Newton Biography - Newton's Life, Career, Work - Dr Robert A. Hatch Isaac Newton, Biography, Information, Sources -Dr Robert A.

Hatch S I R I S A A C N E W T O N Dr Robert A. Hatch - University of Florida Newton, Sir Isaac (1642-1727), English natural philosopher, generally regarded as the most original and influential theorist in the history of science. In addition to his invention of the infinitesimal calculus and a new theory of light and color, Newton transformed the structure of physical science with his three laws of motion and the law of universal gravitation. As the keystone of the scientific revolution of the 17th century, Newton's work combined the contributions of Copernicus, Kepler, Galileo, Descartes, and others into a new and powerful synthesis. Three centuries later the resulting structure - classical mechanics - continues to be a useful but no less elegant monument to his genius. Life & Character - Isaac Newton was born prematurely on Christmas day 1642 (4 January 1643, New Style) in Woolsthorpe, a hamlet near Grantham in Lincolnshire.

The posthumous son of an illiterate yeoman (also named Isaac), the fatherless infant was small enough at birth to fit 'into a quartpot.' When he was barely three years old Newton's mother, Hanna (Ayscough), placed her first born with his grandmother in order to remarry and raise a second family with Barnabas Smith, a wealthy rector from nearby North Witham. Much has been made of Newton's posthumous birth, his prolonged separation from his mother, and his unrivaled hatred of his stepfather. Until Hanna returned to Woolsthorpe in 1653 after the death of her second husband, Newton was denied his mother's attention, a possible clue to his complex character. Newton's childhood was anything but happy, and throughout his life he verged on emotional collapse, occasionally falling into violent and vindictive attacks against friend and foe alike. With his mother's return to Woolsthorpe in 1653, Newton was taken from school to fulfill his birthright as a farmer. Happily, he failed in this calling, and returned to King's School at Grantham to prepare for entrance to Trinity College, Cambridge.

Numerous anecdotes survive from this period about Newton's absent-mindedness as a fledging farmer and his lackluster performance as a student. But the turning point in Newton's life came in June 1661 when he left Woolsthorpe for Cambridge University. Here Newton entered a new world, one he could eventually call his own. Although Cambridge was an outstanding center of learning, the spirit of the scientific revolution had yet to penetrate its ancient and somewhat ossified curriculum. Little is known of Newton's formal studies as an undergraduate, but he likely received large doses of Aristotle as well as other classical authors. And by all appearances his academic performance was undistinguished. In 1664 Isaac Barrow, Lucasian Professor of Mathematics at Cambridge, examined Newton's understanding of Euclid and found it sorely lacking. We now know that during his undergraduate years Newton was deeply engrossed in private study, that he privately mastered the works of René Descartes, Pierre Gassendi, Thomas Hobbes, and other major figures of the scientific revolution.

A series of extant notebooks shows that by 1664 Newton had begun to master Descartes' Géométrie and other forms of mathematics far in advance of Euclid's Elements. Barrow, himself a gifted mathematician, had yet to appreciate Newton's genius. In 1665 Newton took his bachelor's degree at Cambridge without honors or distinction. Since the university was closed for the next two years because of plague, Newton returned to Woolsthorpe in midyear. There, in the following 18 months, he made a series of original contributions to science. As he later recalled, 'All this was in the two plague years of 1665 and 1666, for in those days I was in my prime of age for invention, and minded mathematics and philosophy more than at any time since.' In mathematics Newton conceived his 'method of fluxions' (infinitesimal calculus), laid the foundations for his theory of light and color, and achieved significant insight into the problem of planetary motion, insights that eventually led to the publication of his Principia (1687).

In April 1667, Newton returned to Cambridge and, against stiff odds, was elected a minor fellow at Trinity. Success followed good fortune. In the next year he became a senior fellow upon taking his master of arts degree, and in 1669, before he had reached his 27th birthday, he succeeded Isaac Barrow as Lucasian Professor of Mathematics. The duties of this appointment offered Newton the opportunity to organize the results of his earlier optical researches, and in 1672, shortly after his election to the Royal Society, he communicated his first public paper, a brilliant but no less controversial study on the nature of color. In the first of a series of bitter disputes, Newton locked horns with the society's celebrated curator of experiments, the bright but brittle Robert Hooke. The ensuing controversy, which continued until 1678, established a pattern in Newton's behavior. After an initial skirmish, he quietly retreated. Nonetheless, in 1675 Newton ventured another yet another paper, which again drew lightning, this time charged with claims that he had plagiarized from Hooke. The charges were entirely ungrounded. Twice burned, Newton withdrew.

In 1678, Newton suffered a serious emotional breakdown, and in the following year his mother died. Newton's response was to cut off contact with others and engross himself in alchemical research. These studies, once an embarrassment to Newton scholars, were not misguided musings but rigorous investigations into the hidden forces of nature. Newton's alchemical studies opened theoretical avenues not found in the mechanical philosophy, the world view that sustained his early work. While the mechanical philosophy reduced all phenomena to the impact of matter in motion, the alchemical tradition upheld the possibility of attraction and repulsion at the particulate level. Newton's later insights in celestial mechanics can be traced in part to his alchemical interests. By combining action-at-a-distance and mathematics, Newton transformed the mechanical philosophy by adding a mysterious but no less measurable quantity, gravitational force. In 1666, as tradition has it, Newton observed the fall of an apple in his garden at Woolsthorpe, later recalling, 'In the same year I began to think of gravity extending to the orb of the Moon.' Newton's memory was not accurate.

In fact, all evidence suggests that the concept of universal gravitation did not spring full-blown from Newton's head in 1666 but was nearly 20 years in gestation. Ironically, Robert Hooke helped give it life. In November 1679, Hooke initiated an exchange of letters that bore on the question of planetary motion. Although Newton hastily broke off the correspondence, Hooke's letters provided a conceptual link between central attraction and a force falling off with the square of distance. Sometime in early 1680, Newton appears to have quietly drawn his own conclusions. Meanwhile, in the coffeehouses of London, Hooke, Edmund Halley, and Christopher Wren struggled unsuccessfully with the problem of planetary motion. Finally, in August 1684, Halley paid a legendary visit to Newton in Cambridge, hoping for an answer to his riddle: What type of curve does a planet describe in its orbit around the sun, assuming an inverse square law of attraction? When Halley posed the question, Newton's ready response was 'an ellipse.' When asked how he knew it was an ellipse Newton replied that he had already calculated it.

Although Newton had privately answered one of the riddles of the universe--and he alone possessed the mathematical ability to do so--he had characteristically misplaced the calculation. After further discussion he promised to send Halley a fresh calculation forthwith. In partial fulfillment of his promise Newton produced his De Motu of 1684. From that seed, after nearly two years of intense labor, the Philosophiae Naturalis Principia Mathematica appeared. Arguably, it is the most important book published in the history of science. But if the Principia was Newton's brainchild, Hooke and Halley were nothing less than midwives. Although the Principia was well received, its future was cast in doubt before it appeared. Here again Hooke was center stage, this time claiming (not without justification) that his letters of 1679-1680 earned him a role in Newton's discovery. But to no effect. Newton was so furious with Hooke that he threatened to suppress Book III of the Principia altogether, finally denouncing science as 'an impertinently litigious lady.' Newton calmed down and finally consented to publication.

But instead of acknowledging Hooke's contribution Newton systematically deleted every possible mention of Hooke's name. Newton's hatred for Hooke was consumptive. Indeed, Newton later withheld publication of his Opticks (1704) and virtually withdrew from the Royal Society until Hooke's death in 1703. After publishing the Principia, Newton became more involved in public affairs. In 1689 he was elected to represent Cambridge in Parliament, and during his stay in London he became acquainted with John Locke, the famous philosopher, and Nicolas Fatio de Duillier, a brilliant young mathematician who became an intimate friend. In 1693, however, Newton suffered a severe nervous disorder, not unlike his breakdown of 1677-1678. The cause is open to interpretation: overwork; the stress of controversy; the unexplained loss of friendship with Fatio; or perhaps chronic mercury poisoning, the result of nearly three decades of alchemical research. Each factor may have played a role.

We only know Locke and Samuel Pepys received strange and seemingly deranged letters that prompted concern for Newton's 'discomposure in head, or mind, or both.' Whatever the cause, shortly after his recovery Newton sought a new position in London. In 1696, with the help of Charles Montague, a fellow of Trinity and later earl of Halifax, Newton was appointed Warden and then Master of the Mint. His new position proved 'most proper,' and he left Cambridge for London without regret. During his London years Newton enjoyed power and worldly success. His position at the Mint assured a comfortable social and economic status, and he was an active and able administrator. After the death of Hooke in 1703, Newton was elected president of the Royal Society and was annually reelected until his death. In 1704 he published his second major work, the Opticks, based largely on work completed decades before. He was knighted in 1705. Although his creative years had passed, Newton continued to exercise a profound influence on the development of science. In effect, the Royal Society was Newton's instrument, and he played it to his personal advantage.

His tenure as president has been described as tyrannical and autocratic, and his control over the lives and careers of younger disciples was all but absolute. Newton could not abide contradiction or controversy - his quarrels with Hooke provide singular examples. But in later disputes, as president of the Royal Society, Newton marshaled all the forces at his command. For example, he published Flamsteed's astronomical observations - the labor of a lifetime - without the author's permission; and in his priority dispute with Leibniz concerning the calculus, Newton enlisted younger men to fight his war of words, while behind the lines he secretly directed charge and countercharge. In the end, the actions of the Society were little more than extensions of Newton's will, and until his death he dominated the landscape of science without rival. He died in London on March 20, 1727 (March 31, New Style). Scientific Achievements Mathematics - The origin of Newton's interest in mathematics can be traced to his undergraduate days at Cambridge.

Here Newton became acquainted with a number of contemporary works, including an edition of Descartes Géométrie, John Wallis' Arithmetica infinitorum, and other works by prominent mathematicians. But between 1664 and his return to Cambridge after the plague, Newton made fundamental contributions to analytic geometry, algebra, and calculus. Specifically, he discovered the binomial theorem, new methods for expansion of infinite series, and his 'direct and inverse method of fluxions.' As the term implies, fluxional calculus is a method for treating changing or flowing quantities. Hence, a 'fluxion' represents the rate of change of a 'fluent'--a continuously changing or flowing quantity, such as distance, area, or length. In essence, fluxions were the first words in a new language of physics. Newton's creative years in mathematics extended from 1664 to roughly the spring of 1696. Although his predecessors had anticipated various elements of the calculus, Newton generalized and integrated these insights while developing new and more rigorous methods.

The essential elements of his thought were presented in three tracts, the first appearing in a privately circulated treatise, De analysi (On Analysis),which went unpublished until 1711. In 1671, Newton developed a more complete account of his method of infinitesimals, which appeared nine years after his death as Methodus fluxionum et serierum infinitarum (The Method of Fluxions and Infinite Series, 1736). In addition to these works, Newton wrote four smaller tracts, two of which were appended to his Opticks of 1704. Newton and Leibniz. Next to its brilliance, the most characteristic feature of Newton's mathematical career was delayed publication. Newton's priority dispute with Leibniz is a celebrated but unhappy example. Gottfried Wilhelm Leibniz, Newton's most capable adversary, began publishing papers on calculus in 1684, almost 20 years after Newton's discoveries commenced. The result of this temporal discrepancy was a bitter dispute that raged for nearly two decades. The ordeal began with rumors that Leibniz had borrowed ideas from Newton and rushed them into print. It ended with charges of dishonesty and outright plagiarism.

The Newton-Leibniz priority dispute--which eventually extended into philosophical areas concerning the nature of God and the universe--ultimately turned on the ambiguity of priority. It is now generally agreed that Newton and Leibniz each developed the calculus independently, and hence they are considered co-discoverers. But while Newton was the first to conceive and develop his method of fluxions, Leibniz was the first to publish his independent results. Optics. Newton's optical research, like his mathematical investigations, began during his undergraduate years at Cambridge. But unlike his mathematical work, Newton's studies in optics quickly became public. Shortly after his election to the Royal Society in 1671, Newton published his first paper in the Philosophical Transactions of the Royal Society. This paper, and others that followed, drew on his undergraduate researches as well as his Lucasian lectures at Cambridge. In 1665-1666, Newton performed a number of experiments on the composition of light. Guided initially by the writings of Kepler and Descartes, Newton's main discovery was that visible (white) light is heterogeneous--that is, white light is composed of colors that can be considered primary.

Through a brilliant series of experiments, Newton demonstrated that prisms separate rather than modify white light. Contrary to the theories of Aristotle and other ancients, Newton held that white light is secondary and heterogeneous, while the separate colors are primary and homogeneous. Of perhaps equal importance, Newton also demonstrated that the colors of the spectrum, once thought to be qualities, correspond to an observed and quantifiable 'degree of Refrangibility.' The Crucial Experiment. Newton's most famous experiment, the experimentum crucis, demonstrated his theory of the composition of light. Briefly, in a dark room Newton allowed a narrow beam of sunlight to pass from a small hole in a window shutter through a prism, thus breaking the white light into an oblong spectrum on a board. Then, through a small aperture in the board, Newton selected a given color (for example, red) to pass through yet another aperture to a second prism, through which it was refracted onto a second board. What began as ordinary white light was thus dispersed through two prisms. Newton's 'crucial experiment' demonstrated that a selected color leaving the first prism could not be separated further by the second prism. The selected beam remained the same color, and its angle of refraction was constant throughout.

Newton concluded that white light is a 'Heterogeneous mixture of differently refrangible Rays' and that colors of the spectrum cannot themselves be individually modified, but are 'Original and connate properties.' Newton probably conducted a number of his prism experiments at Cambridge before the plague forced him to return to Woolsthorpe. His Lucasian lectures, later published in part as Optical Lectures (1728), supplement other researches published in the Society's Transactions dating from February 1672. The Opticks. The Opticks of 1704, which first appeared in English, is Newton's most comprehensive and readily accessible work on light and color. In Newton's words, the purpose of the Opticks was 'not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments.' Divided into three books, the Opticks moves from definitions, axioms, propositions, and theorems to proof by experiment. A subtle blend of mathematical reasoning and careful observation, the Opticks became the model for experimental physics in the 18th century. The Corpuscular Theory. But the Opticks contained more than experimental results.

During the 17th century it was widely held that light, like sound, consisted of a wave or undulatory motion, and Newton's major critics in the field of optics--Robert Hooke and Christiaan Huygens--were articulate spokesmen for this theory. But Newton disagreed. Although his views evolved over time, Newton's theory of light was essentially corpuscular, or particulate. In effect, since light (unlike sound) travels in straight lines and casts a sharp shadow, Newton suggested that light was composed of discrete particles moving in straight lines in the manner of inertial bodies. Further, since experiment had shown that the properties of the separate colors of light were constant and unchanging, so too, Newton reasoned, was the stuff of light itself-- particles. At various points in his career Newton in effect combined the particle and wave theories of light. In his earliest dispute with Hooke and again in his Opticks of 1717, Newton considered the possibility of an ethereal substance--an all-pervasive elastic material more subtle than air--that would provide a medium for the propagation of waves or vibrations.

From the outset Newton rejected the basic wave models of Hooke and Huygens, perhaps because they overlooked the subtlety of periodicity. The question of periodicity arose with the phenomenon known as 'Newton's rings.' In book II of the Opticks, Newton describes a series of experiments concerning the colors of thin films. His most remarkable observation was that light passing through a convex lens pressed against a flat glass plate produces concentric colored rings (Newton's rings) with alternating dark rings. Newton attempted to explain this phenomenon by employing the particle theory in conjunction with his hypothesis of 'fits of easy transmission [refraction] and reflection.' After making careful measurements, Newton found that the thickness of the film of air between the lens (of a given curvature) and the glass corresponded to the spacing of the rings. If dark rings occurred at thicknesses of 0, 2, 4, 6... , then the colored rings corresponded to an odd number progression, 1, 3, 5, 7, .... Although Newton did not speculate on the cause of this periodicity, his initial association of 'Newton's rings' with vibrations in a medium suggests his willingness to modify but not abandon the particle theory.

The Opticks was Newton's most widely read work. Following the first edition, Latin versions appeared in 1706 and 1719, and second and third English editions in 1717 and 1721. Perhaps the most provocative part of the Opticks is the section known as the 'Queries,' which Newton placed at the end of the book. Here he posed questions and ventured opinions on the nature of light, matter, and the forces of nature. Mechanics. Newton's research in dynamics falls into three major periods: the plague years 1664-1666, the investigations of 1679-1680, following Hooke's correspondence, and the period 1684-1687, following Halley's visit to Cambridge. The gradual evolution of Newton's thought over these two decades illustrates the complexity of his achievement as well as the prolonged character of scientific 'discovery.' While the myth of Newton and the apple maybe true, the traditional account of Newton and gravity is not.

To be sure, Newton's early thoughts on gravity began in Woolsthorpe, but at the time of his famous 'moon test' Newton had yet to arrive at the concept of gravitational attraction. Early manuscripts suggest that in the mid-1660's, Newton did not think in terms of the moon's central attraction toward the earth but rather of the moon's centrifugal tendency to recede. Under the influence of the mechanical philosophy, Newton had yet to consider the possibility of action- at-a-distance; nor was he aware of Kepler's first two planetary hypotheses. For historical, philosophical, and mathematical reasons, Newton assumed the moon's centrifugal 'endeavour' to be equal and opposite to some unknown mechanical constraint. For the same reasons, he also assumed a circular orbit and an inverse square relation. The latter was derived from Kepler's third hypothesis (the square of a planet's orbital period is proportional to the cube of its mean distance from the sun), the formula for centrifugal force (the centrifugal force on a revolving body is proportional to the square of its velocity and inversely proportional to the radius of its orbit), and the assumption of circular orbits. The next step was to test the inverse square relation against empirical data.

To do this Newton, in effect, compared the restraint on the moon's 'endeavour' to recede with the observed rate of acceleration of falling objects on earth. The problem was to obtain accurate data. Assuming Galileo's estimate that the moon is 60 earth radii from the earth, the restraint on the moon should have been 1/3600 (1/602) of the gravitational acceleration on earth. But Newton's estimate of the size of the earth was too low, and his calculation showed the effect on the moon to be about 1/4000 of that on earth. As Newton later described it, the moon test answered 'pretty nearly.' But the figures for the moon were not exact, and Newton abandoned the problem. In late 1679 and early 1680 an exchange of letters with Hooke renewed Newton's interest. In November 1679, nearly 15 years after the moon test, Hooke wrote Newton concerning a hypothesis presented in his Attempt to Prove the Motion of the Earth (1674).

Here Hooke proposed that planetary orbits result from a tangential motion and 'an attractive motion towards the centrall body.' In later letters Hooke further specified a central attracting force that fell off with the square of distance. As a result of this exchange Newton rejected his earlier notion of centrifugal tendencies in favor of central attraction. Hooke's letters provided crucial insight. But in retrospect, if Hooke's intuitive power seems unparalleled, it never approached Newton's mathematical power in principle or in practice. When Halley visited Cambridge in 1684, Newton had already demonstrated the relation between an inverse square attraction and elliptical orbits. To Halley's 'joy and amazement,' Newton apparently succeeded where he and others failed. With this, Halley's role shifted, and he proceeded to guide Newton toward publication. Halley personally financed the Principia and saw it through the press to publication in July 1687. The Principia. Newton's masterpiece is divided into three books. Book I of the Principia begins with eight definitions and three axioms, the latter now known as Newton's laws of motion.

No discussion of Newton would be complete without them: (1) Every body continues in its state of rest, or uniform motion in a straight line, unless it is compelled to change that state by forces impressed on it (inertia). (2) The change in motion is proportional to the motive force impressed and is made in the direction of the straight line in which that force is impressed (F = ma). (3) To every action there is always an opposed and equal reaction. Following these axioms, Newton proceeds step by step with propositions, theorems, and problems. In Book II of the Principia, Newton treats the Motion of bodies through resisting mediums as well as the motion of fluids themselves. Since Book II was not part of Newton's initial outline, it has traditionally seemed somewhat out of place. Nonetheless, it is noteworthy that near the end of Book II (Section IX) Newton demonstrates that the vortices invoked by Descartes to explain planetary motion could not be self-sustaining; nor was the vortex theory consistent with Kepler's three planetary rules. The purpose of Book II then becomes clear.

After discrediting Descartes' system, Newton concludes: 'How these motions are performed in free space without vortices, may be understood by the first book; and I shall now more fully treat of it in the following book.' In Book III, subtitled the System of the World, Newton extended his three laws of motion to the frame of the world, finally demonstrating 'that there is a power of gravity tending to all bodies, proportional to the several quantities of matter which they contain.' Newton's law of universal gravitation states that F = G Mm/R2; that is, that all matter is mutually attracted with a force (F) proportional to the product of their masses (Mm) and inversely proportional to the square of distance (R2) between them. G is a constant whose value depends on the units used for mass and distance. To demonstrate the power of his theory, Newton used gravitational attraction to explain the motion of the planets and their moons, the precession of equinoxes, the action of the tides, and the motion of comets. In sum, Newton's universe united heaven and earth with a single set of laws. It became the physical and intellectual foundation of the modern world view.

Perhaps the most powerful and influential scientific treatise ever published, the Principia appeared in two further editions during Newton's lifetime, in 1713 and 1726. Other Researches. Throughout his career Newton conducted research in theology and history with the same passion that he pursued alchemy and science. Although some historians have neglected Newton's nonscientific writings, there is little doubt of his devotion to these subjects, as his manuscripts amply attest. Newton's writings on theological and biblical subjects alone amount to about 1.3 million words, the equivalent of 20 of today's standard length books. Although these writings say little about Newtonian science, they tell us a good deal about Isaac Newton. Newton's final gesture before death was to refuse the sacrament, a decision of some consequence in the 18th century. Although Newton was dutifully raised in the Protestant tradition his mature views on theology were neither Protestant, traditional, nor orthodox. In the privacy of his thoughts and writings, Newton rejected a host of doctrines he considered mystical, irrational, or superstitious. In a word, he was a Unitarian. Newton's research outside of science--in theology, prophecy, and history--was a quest for coherence and unity.

His passion was to unite knowledge and belief, to reconcile the Book of Nature with the Book of Scripture. But for all the elegance of his thought and the boldness of his quest, the riddle of Isaac Newton remained. In the end, Newton is as much an enigma to us as he was, no doubt, to himself. Robert A. Hatch

Question: Near which Lincolnshire village did the apple fall on Newton?s head?
Answer: WOOLSTHORPE