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Robert Hooke (; 18 July 16353 March 1703) was an English polymath who was active as a physicist ("natural philosopher"), astronomer, geologist, meteorologist, and architect. He is credited as one of the first scientists to investigate living things at microscopic scale in 1665, using a compound microscope that he designed. Hooke was an impoverished scientific inquirer in young adulthood who went on to become one of the most important scientists of his time. After the Great Fire of London in 1666, Hooke (as a surveyor and architect) attained wealth and esteem by performing more than half of the property line surveys and assisting with the city's rapid reconstruction. Often vilified by writers in the centuries after his death, his reputation was restored at the end of the twentieth century and he has been called "England's Leonardo da".
Hooke was a Fellow of the Royal Society and from 1662, he was its first Curator of Experiments. From 1665 to 1703, he was also Professor of Geometry at Gresham College. Hooke began his scientific career as an assistant to the physical scientist Robert Boyle. Hooke built the that were used in Boyle's experiments on gas law and also conducted experiments. In 1664, Hooke identified the rotations of Mars and Jupiter. Hooke's 1665 book Micrographia, in which he coined the term cell, encouraged microscopic investigations. Investigating optics specifically light refraction Hooke inferred a wave theory of light. His is the first-recorded hypothesis of the cause of the expansion of matter by heat, of air's composition by small particles in constant motion that thus generate its pressure, and of heat as energy.
In physics, Hooke inferred that gravity obeys an inverse square law and arguably was the first to hypothesise such a relation in planetary motion, a principle Isaac Newton furthered and formalised in Newton's law of universal gravitation. Priority over this insight contributed to the rivalry between Hooke and Newton. In geology and paleontology, Hooke originated the theory of a globe, thus disputing the Biblical view of the Earth's age; he also hypothesised the extinction of species, and argued hills and mountains had become elevated by geological processes. By identifying fossils of extinct species, Hooke presaged the Evolution.
Hooke was born in 1635 in Freshwater, Isle of Wight, to Cecily Gyles and the Anglican priest John Hooke, who was the curate of All Saints' Church, Freshwater. Robert was the youngest, by seven years, of four siblings (two boys and two girls); he was frail and not expected to live. Although his father gave him some instruction in English, (Latin) Grammar, and Divinity, Robert's education was largely neglected. Left to his own devices, he made little mechanical toys; seeing a brass clock dismantled, he built a wooden replica that "would go".
Hooke's father died in October 1648, leaving £40 in his will to Robert (plus another £10 held over from his grandmother). At the age of 13, he took this to London to become an apprentice to the celebrated painter Peter Lely. Hooke also had "some instruction in drawing" from the limner Samuel Cowper but "the smell of the Oil Colours did not agree with his Constitution, increasing his Head-ache to which he was ever too much subject", and he became a pupil at Westminster School, living with its master Richard Busby. Hooke quickly mastered Latin, Greek, and Euclid's Elements; he also learnt to play the pipe organ and began his lifelong study of mechanics. He remained an accomplished draughtsman, as he was later to demonstrate in his drawings that illustrate the work of Robert Boyle and Hooke's own Micrographia.
While a student at Oxford, Hooke was also employed as an assistant to Dr Thomas Willis a physician, chemist, and member of the Oxford Philosophical Club. The Philosophical Club had been founded by John Wilkins, Warden of Wadham College, who led this important group of scientists who went on to form the nucleus of the Royal Society. In 1659, Hooke described to the Club some elements of a method of heavier-than-air flight but concluded human muscles were insufficient to the task. Through the Club, Hooke met Seth Ward (the University's Savilian Professor of Astronomy) and developed for Ward a mechanism that improved the regularity of pendulum clocks used for astronomical time-keeping. Hooke characterised his Oxford days as the foundation of his lifelong passion for science. The friends he made there, particularly Christopher Wren, were important to him throughout his career. Willis introduced Hooke to Robert Boyle, who the Club sought to attract to Oxford.
In 1655, Boyle moved to Oxford and Hooke became nominally his assistant but in practice his co-experimenter. Boyle had been working on gas pressures; the possibility a vacuum might exist despite Aristotle's maxim "Nature abhors a vacuum" had just begun to be considered. Hooke developed an air pump for Boyle's experiments rather than use Ralph Greatorex's pump, which Hooke considered as "too gross to perform any great matter". Hooke's engine enabled the development of the Boyles Law that was subsequently attributed to Boyle; Hooke had a particularly keen eye and was an adept mathematician, neither of which applied to Boyle. Hooke taught Boyle Euclid's Elements and Descartes's Principles of Philosophy; it also caused them to recognise fire as a chemical reaction and not, as Aristotle taught, a fundamental element of nature.
The Royal Society was founded in 1660 and given its Royal Charter in July 1662. On 5 November 1661, Robert Moray proposed the appointment of a curator to furnish the society with experiments and this was unanimously passed and Hooke was named on Boyle's recommendation. The Society did not have a reliable income to fully fund the post of Curator of Experiments but in 1664, John Cutler settled an annual gratuity of £50 on the Society to found a "" lectureship at Gresham College on the understanding the Society would appoint Hooke to this task. On 27 June 1664, Hooke was confirmed to the office and on 11 January 1665, he was named Curator by Office for life with an annual salary of £80, which consisting of £30 from the Society and Cutler's £50 annuity.
In June 1663, Hooke was elected a Fellow of the Royal Society (FRS). On 20 March 1665, he was also appointed Gresham Professor of Geometry. On 13 September 1667, Hooke became acting Secretary of the Society and on 19 December 1677, he was appointed its Joint Secretary.
The publication of Hooke's diary in 1935 revealed previously unknown details about his social and familial relationships. His biographer Margaret said: "the picture which is usually painted of Hooke as a recluse is completely false". He interacted with noted artisans such as clock-maker Thomas Tompion and instrument-maker Christopher Cocks (Cox). Hooke often met Christopher Wren, with whom he shared many interests, and had a lasting friendship with John Aubrey. His diaries also make frequent reference to meetings at coffeehouses and taverns, as well as to dinners with Robert Boyle. On many occasions, Hooke took tea with his lab assistant Harry Hunt. Although he largely lived aloneapart from the servants who ran his home his niece Grace Hooke and his cousin Tom Giles lived with him for some years as children.
Hooke never married. According to his diary, Hooke had a sexual relationship with his niece Grace, after she had turned 16. Grace was in his custody since the age of 10. He also had sexual relations with several maids and housekeepers. Hooke's biographer Stephen Inwood considers Grace to have been the love of his life, and he was devastated when she died in 1687. Inwood also mentions "The age difference between him and Grace was commonplace and would not have upset his contemporaries as it does us". The incestous relationship would nevertheless have been frowned upon and tried by an ecclesiastical court had it been discovered, it was not however a capital felony after 1660.
Since childhood, Hooke suffered from migraine, tinnitus, dizziness, and bouts of insomnia; he also had a spinal deformity that was consistent with a diagnosis of Scheuermann's kyphosis, giving him in middle and later years a "thin and crooked body, over-large head and protruding eyes". Approaching these in a scientific spirit, he experimented with self-medication, diligently recording symptoms, substances, and effects in his diary. He regularly used sal ammoniac, emetics, laxatives, and opiates, which appear to have had an increasing effect on his physical and mental health over time.
Hooke died in London on 3 March 1703, having been blind and bedridden during the last year of his life. A chest containing £8,000 in money and gold was found in his room at Gresham College. His library contained over 3,000 books in Latin, French, Italian, and English. Although he had talked of leaving a generous bequest to the Royal Society, which would have given his name to a library, laboratory, and lectures, no will was found and the money passed to a cousin named Elizabeth Stephens. Hooke was buried at St Helen's Church, Bishopsgate, in the City of London but the precise location of his grave is unknown.
One of the most-challenging problems Hooke investigated was the measurement of the distance from Earth to a star other than the Sun. Hooke selected the star Gamma Draconis and chose the method of parallax determination. In 1669, after several months of observing, Hooke believed the desired result had been achieved. It is now known his equipment was far too imprecise to obtain an accurate measurement.
Hooke's Micrographia contains illustrations of the Pleiades star cluster and lunar craters. He conducted experiments to investigate the formation of these craters and concluded their existence meant the Moon must have its own gravity, a radical departure from the contemporaneous Aristotelian celestial model. He also was an early observer of the rings of Saturn, and discovered one of the first-observed , Gamma Arietis (a visual binary), in 1664.
To achieve these discoveries, Hooke needed better instruments than those that were available at the time. Accordingly, he invented three new mechanisms: the Hooke joint, a sophisticated universal joint that allowed his instruments to smoothly follow the apparent motion of the observed body; the first clockwork drive to automate the process; and a micrometer screw that allowed him to achieve a precision of ten seconds of arc. Hooke was dissatisfied with refracting telescopes so he built the first practical Gregorian telescope that used a silvered glass mirror.
Hooke's announcement of his law of elasticity using an anagram was a method scientists, such as Hooke, Huygens, and Galileo, sometimes used to establish priority for a discovery without revealing details. Hooke used mechanical analogues to understand fundamental processes such as the motion of a spherical pendulum and of a ball in a hollow cone, to demonstrate central force due to gravity, and a hanging chain net with point loads to provide the optimum shape for a dome with heavy cross on top.
Despite continuing reports to the contrary, Hooke did not influence Thomas Newcomen's invention of the steam engine; this myth, which originated in an article in the third edition of Encyclopædia Britannica, has been found to be mistaken.
Hooke's 1674 Gresham lecture, An Attempt to Prove the Motion of the Earth by Observations (published 1679), said gravitation applies to "all celestial bodies" and restated these three propositions.
Hooke's statements up to 1674 make no mention, however, that an inverse square law applies or might apply to these attractions. His model of gravitation was also not yet universal, though it approached universality more closely than previous hypotheses. Hooke did not provide accompanying evidence or mathematical demonstration; he stated in 1674: "Now what these several degrees of are I have not yet experimentally verified", indicating he did not yet know what law the gravitation might follow; and about his whole proposal, he said: "This I only hint at present ... having my self many other things in hand which I would first , and therefore cannot so well attend it" (i.e. "prosecuting this Inquiry").
In November 1679, Hooke initiated a notable exchange of letters with Newton that was published in 1960. Hooke's ostensible purpose was to tell Newton he (Hooke) had been appointed to manage the Royal Society's correspondence; Hooke therefore wanted to hear from members about their research or their views about the research of others. Hooke asked Newton's opinions about various matters. Among other items, Hooke mentioned "compounding the celestial motions of the planets of a direct motion by the tangent and an attractive motion towards the central body"; his "hypothesis of the or causes of springinesse"; a new hypothesis from Paris about planetary motions, which he described at length; efforts to carry out or improve national surveys; and the difference of latitude between London and Cambridge.
Newton's reply offered "a of my own" about a terrestrial experiment rather than a proposal about celestial motions that might detect the Earth's motion; the experiment would use a body suspended in air and then dropped. Hooke wanted to discern how Newton thought the falling body could experimentally reveal the Earth's motion by its direction of deviation from the vertical but Hooke went on hypothetically to consider how its motion could continue if the solid Earth had not been in the way, on a spiral path to the centre. Hooke disagreed with Newton's idea of the body's continuing motion. A further short correspondence developed; towards the end of it, writing on 6 January 1680 to Newton, Hooke communicated his "supposition ... that the Attraction always is in a duplicate proportion to the Distance from the , and Consequently that the Velocity will be in a subduplicate proportion to the Attraction and Consequently as Kepler Supposes to the Distance". (Hooke's inference about the velocity is incorrect.)
In 1686, when the first book of Newton's Principia was presented to the Royal Society, Hooke said he had given Newton the "notion" of "the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the ". At the same time, according to Edmond Halley's contemporaneous report, Hooke agreed "the Demonstration of the Curves generated thereby" was wholly Newton's.
According to a 2002 assessment of the early history of the inverse square law: "by the late 1660s, the assumption of an 'inverse proportion between gravity and the square of distance' was rather common and had been advanced by a number of different people for different reasons". In the 1660s, Newton had shown for planetary motion under a circular assumption, force in the radial direction had an inverse-square relation with distance from the centre. Newton, who in May 1686 was presented with Hooke's claim to priority on the inverse square law, denied he was to be credited as author of the idea, giving reasons including the citation of prior work by others. Newton also said that, even if he had first heard of the inverse square proportion from Hooke (which Newton said he had not), he would still have some rights to it because of his mathematical developments and demonstrations. These, he said, enabled observations to be relied upon as evidence of its accuracy while according to Newton, Hooke, without mathematical demonstrations and evidence in favour of the supposition, could only guess it was approximately valid "at great distances from the centre".
Newton accepted and acknowledged, in all editions of his Principia, that Hooke and others had separately appreciated the inverse square law in the solar system. Newton acknowledged Wren, Hooke, and Halley in this connection in his "Scholium to Proposition 4" in Book1. In a letter to Halley, Newton also acknowledged his correspondence with Hooke in 1679–1680 had reawakened his dormant interest in astronomical matters but that did not mean, according to Newton, Hooke had told Newton anything new or original. Newton wrote:
Whilst Newton was primarily a pioneer in mathematical analysis and its applications, and optical experimentation, Hooke was a creative experimenter of such great range who left some of his ideas, such as those about gravitation, undeveloped. In 1759, decades after the deaths of both Newton and Hooke, Alexis Clairaut, mathematical astronomer eminent in his own right in the field of gravitational studies, reviewed Hooke's published work on gravitation. According to Stephen Peter Rigaud, Clairaut wrote: "The example of Hooke and that of Kepler serves to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated". I. Bernard Cohen said: "Hooke's claim to the inverse-square law has masked Newton's far more fundamental debt to him, the analysis of curvilinear orbital motion. In asking for too much credit, Hooke effectively denied to himself the credit due him for a seminal idea".
Galileo had observed the regularity of a pendulum and Huygens first incorporated it in a clock; in 1668, Hooke demonstrated his new device to keep a pendulum swinging regularly in unsteady conditions. His invention of a tooth-cutting machine enabled a substantial improvement in the accuracy and precision of timepieces. Waller reported the invention was, by Hooke's death, in constant use among clock makers.
Hooke announced he conceived a way to build a marine chronometer to determine longitude. and with the help of Boyle and others, he attempted to patent it. In the process, Hooke demonstrated a pocket-watch of his own devising that was fitted with a coil spring attached to the arbour of the balance. Hooke's refusal to accept an escape clause in the proposed exclusive contract for the use of this idea resulted in its abandonment.
Hooke developed the principle of the balance spring independently of Huygens and at least five years beforehand. Huygens published his own work in Journal de Scavans in February 1675 and built the first functioning watch to use a balance spring.
Micrographia also contains Hooke's, or perhaps Boyle's and Hooke's, ideas on combustion. Hooke's experiments led him to conclude combustion involves a component of air, a statement with which modern scientists would agree but that was not understood widely, if at all, in the seventeenth century. He also concluded respiration and combustion involve a specific and limited component of air. According to Partington, if "Hooke had continued his experiments on combustion, it is probable that he would have discovered oxygen".
Samuel Pepys wrote of the book in his diary on 21 January 16: "Before I went to bed I sat up till two o’clock in my chamber reading of Mr. Hooke's Observations, the most ingenious book that ever I read in my life".
In 1835, Charles Lyell, the Scottish geologist and associate of Charles Darwin, wrote of Hooke in Principles of Geology: "His treatise ... is the most philosophical production of that age, in regard to the causes of former changes in the organic and inorganic kingdoms of nature".
Wren and Hooke were both keen astronomers. The Monument to the Great Fire of London was designed to serve a scientific function as a zenith telescope for astronomical observation, though traffic vibration made it unusable for this purpose. The legacy of this can be observed in the construction of the spiral staircase, which has no central column, and in the observation chamber, which remains in place below ground level. He also collaborated with Wren on the design of St Paul's Cathedral; Hooke determined the ideal shape of an arch is an inverted catenary and thence that a circular series of such arches makes an ideal shape for the cathedral's dome.
In the reconstruction after the Great Fire, Hooke proposed redesigning London's streets on a grid pattern with wide boulevards and arteries, for which Wren and others also submitted proposals. The King decided both the prospective cost of building and compensation, and the need to quickly restore trade and population meant the city would be rebuilt on the original property lines. Hooke was given the task of surveying the ruins to identify foundations, street edges, and property boundaries. He was closely involved with the drafting of an Act of Common Council (April 1667), which set out the process by which the original foundations would be formally recognised and certificated. According to Lisa Jardine: "in the four weeks from the 4th of October, Hooke helped map the fire-damaged area, began compiling a Land Information System for London, and drew up building regulations for an Act of Parliament to govern the rebuilding". Stephen Inwood said: "the surveyors' reports, which were generally written by Hooke, show an admirable ability to get to the nub of intricate neighbourly squabbles, and to produce a crisp and judicious recommendation from a tangle of claims and counter-claims".
Hooke also had to measure and certify land that would be eminent domain for the planned road widening so compensation could be paid. In 1670, he was appointed Surveyor of the Royal Works. Hooke's precise and detailed surveys enabled the production in 1677 of John Ogilby and Morgan's large-scale map of London, the first-known to be of a specific scale (1:1200).
Two contemporaneous, written descriptions of Hooke's appearance have survived; his close friend John Aubrey described him in middle age and at the height of his creative powers:
Richard Waller, writing in 1705 in The Posthumous Works of Robert Hooke, described the elderly Hooke:
On 3 July 1939, Time magazine published a portrait, supposedly of Hooke, but when Ashley Montagu traced the source, it was found to lack a verifiable connection to Hooke. Montagu found the two contemporaneous written descriptions of Hooke's appearance agree with one another but that neither matches the portrait in Time.
In 2003, historian Lisa Jardine conjectured that a recently discovered portrait was of Hooke, but this proposal was disproved by William B. Jensen of the University of Cincinnati who identified the subject as the Flemish scholar Jan Baptist van Helmont.
Other possible likenesses of Hooke include:
In 2003, the amateur painter Rita Greer embarked on a project to memorialise Hooke and produce credible images of him, both painted and drawn, which she believes match Aubrey's and Waller's descriptions of him. Greer's images of Hooke, which are free to use under the Free Art License, have been used for television programmes in the UK and the US, in books and magazines, and for public relations.
In 2019, Larry Griffing, an associate professor in Biology at Texas A&M University, proposed that a portrait by Mary Beale of an unknown sitter and referred to as Portrait of a Mathematicianis actually of Hooke, noting the physical features of the sitter in the portrait match Hooke's. The figure points to a drawing of elliptical motion that appears to match an unpublished manuscript created by him. The painting also includes an orrery depicting the same principle. According to Griffing, buildings included in the image are of Lowther Castle, now in Cumbria, and its Church of St Michael. The church was renovated under one of Hooke's architectural commissions, which Beale would have known from her extensive body of work for the Lowther family. According to Griffing, the painting would once have been owned by the Royal Society but was abandoned when Newton, its president, moved the Society's headquarters in 1710. Christopher Whittaker of the School of Education, University of Durham, England, has questioned Griffing's analysis; according to Whittaker, it is more likely to be of Isaac Barrow. In a response to Whittaker, Griffing reaffirmed his deduction.
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