Robert Hooke, FRS (18 July 1635 – 3 March 1703) was an English natural philosopher, architect and polymath who played an important role in the scientific revolution, through both experimental and theoretical work.
His life divides roughly into three parts: early life as a brilliant but impecunious scientific inquirer; the period after the great fire of 1666 in which he achieved great wealth and standing due to his reputation for hard work and scrupulous honesty; and later life dogged by ill-health and dominated by jealous intellectual disputes. This last is primarily responsible for his relative obscurity in the centuries since his death.
Hooke is known for his law of elasticity (Hooke's Law), his work as "the father of microscopy", and for coining the term "cell" to describe the basic unit of life. Even now there is much less written about him than might be expected from the sheer industry of his life: he was at one time simultaneously the curator of experiments of the Royal Society and a member of its council, Gresham Professor of Geometry and a Surveyor to the City of London after the fire of 1666, in which capacity he appears to have performed more than half of all the surveys after the fire. He was also an important architect of his time, though few of his buildings now survive and some of those are generally misattributed, and was instrumental in devising a set of planning controls for London whose influence remains today. Allan Chapman has characterised him as "England's Leonardo".
Hooke studied at Wadham College during the Protectorate where he became one of a tightly-knit group of ardent Royalists centred around John Wilkins. Here he was employed as an assistant to Thomas Willis and to Robert Boyle, for whom he built the vacuum pumps used in Boyle's gas law experiments. He built some of the earliest Gregorian telescopes, observed the rotations of Mars and Jupiter, and, based on his observations of fossils, was an early proponent of biological evolution. He investigated the phenomenon of refraction, deducing the wave theory of light, and was the first to suggest that matter expands when heated and that air is made of small particles separated by relatively large distances. He performed pioneering work in the field of surveying and map-making and was involved in the work that led to the first modern plan-form map, though his plan for London on a grid system was rejected in favour of rebuilding along the existing routes. He also came near to deducing that gravity follows an inverse square law, and that such a relation governs the motions of the planets, an idea which was subsequently developed by Newton. Much of Hooke's scientific work was conducted in his capacity as curator of experiments of the Royal Society, a post he held from 1662, or as part of the household of Robert Boyle.
Hooke was also irascible, at least in later life, proud, and prone to take umbrage with intellectual competitors, though he was by all accounts also a staunch friend and ally and was loyal always to the circle of ardent Royalists with whom he had his early training at Wadham College, particularly Christopher Wren. His reputation suffered after his death and this is popularly attributed to a dispute with Isaac Newton over credit for his work on gravitation and to a lesser degree light; Newton, as President of the Royal Society, did much to obscure Hooke, including, it is said, destroying (or failing to preserve) the only known portrait of the man. It did not help that the first life of Wren, Parentalis, was written by Wren's son, and tended to exaggerate Wren's work over all others. Hooke's reputation was revived during the twentieth century through studies of Robert Gunther and Margaret 'Espinasse, and after a long period of relative obscurity he is now recognized as one of the most important scientists of his age.
Much of what is known of Hooke's early life comes from an autobiography that he commenced in 1696, but did not complete. This was referenced by Richard Waller in his introduction to the The Posthumous Works of Robert Hooke, M.D. S.R.S., printed in 1705. The work of Waller, along with John Ward's Lives of the Gresham Professors and John Aubrey's Brief Lives, form the major near-contemporaneous biographical accounts of Hooke.
Robert Hooke was born in 1635 in Freshwater on the Isle of Wight to John Hooke and Cecily Gyles. Robert was the last of four children, two brothers and two sisters, and there was an age difference of seven years between him and the next youngest. Their father ecclesiastically served the Church of England, specifically as the curate of Freshwater's Church of All Saints; his three brothers were also ministers. Robert Hooke was expected to succeed in his education and join the Church.
John Hooke also was in charge of a local school, and so was able to teach Robert, at least partly at home perhaps due to the boy's frail health. He was a Royalist and almost certainly a member of a group who went to pay their respects to Charles II when he escaped to the Isle of Wight. Robert, too, grew up to be a staunch monarchist.
As a youth, Robert Hooke was fascinated by observation, mechanical works, and drawing, interests that would be pursued in various ways throughout his life. He dismantled a brass clock and built a wooden replica that, by all accounts, worked "well enough", and he learned to draw, making his own materials from coal, chalk and ruddle (Iron ore).
On his father's death in 1648, Robert was left a sum of one hundred pounds that enabled him to buy an apprenticeship; with his poor health throughout his life but evident mechanical facility his father had it in mind that he might become a watchmaker or limner, though Hooke was also interested in painting. Hooke was an apt student, so although he went to London to take up an apprenticeship, and studied briefly with Samuel Cowper and Peter Lely, he was soon able to enter Westminster School in London, under Dr. Busby, where he lodged his hundred pounds. Hooke quickly mastered Latin and Greek, made some study of Hebrew, and mastered Euclid's Elements. Here, too, he embarked on his life-long study of mechanics.
It appears that Hooke was one of a group of students whom Busby educated in parallel to the main work of the school. Contemporary accounts say he was "not much seen" in the school, and this appears to be true of others in a similar position. Busby, an ardent and outspoken Royalist (he had the school observe a fast-day on the anniversary of the King's beheading), was by all accounts trying to preserve the nascent spirit of scientific inquiry that had begun to flourish in Carolean England but which was at odds with the literal Biblical teachings of the Protectorate. To Busby and his select students the Anglican Church was a framework to support the spirit of inquiry into God's work, those who were able were destined by God to explore and study His creation, and the priesthood functioned as teachers to explain it to those who were less able. This was exemplified in the person of George Hooper, the Bishop of Bath and Wells, whom Busby described as "the best scholar, the finest gentleman and will make the completest bishop that ever was educated at Westminster School".
Hooke himself characterised his Oxford days as the foundation of his life-long passion for science, and the friends he made there were of paramount importance to him throughout his career, particularly Christopher Wren. Wadham was then under the guidance of John Wilkins, who had a profound impact on Hooke and those around him. Wilkins was also a Royalist, and acutely conscious of the turmoil and uncertainty of the times. There was a sense of urgency in preserving the scientific work which they perceived as being threatened by the Protectorate. Wilkins' "philosophical meetings" in his study were clearly important, though few records survive except for the experiments Boyle conducted in 1658 and published in 1660. This group went on to form the nucleus of the Royal Society. Hooke developed an air pump for Boyle's experiments based on the pump of Valentine Greatorex, which was considered, in Hooke's words, "too gross to perform any great matter."
It is known that Hooke had a particularly keen eye, and was an adept mathematician, neither of which applied to Boyle. Gunther suggests that Hooke probably made the observations and may well have developed the mathematics of Boyle's Law. Regardless, it is clear that Hooke was a valued assistant to Boyle and the two retained a mutual high regard.
A chance surviving copy of Willis' pioneering De anima brutorum, a gift the author, was chosen by Hooke from Wilkins' library on his death as a memento at John Tillotson's invitation. This book is now in the Wellcome Library. The book and its inscription in Hooke's hand are a testament ot the lasting influence of Wilkins and his circle on the young Hooke.
In 1655, according to his autobiographical notes, Hooke began to acquaint himself with astronomy, through the good offices of John Ward. Hooke applied himself to the improvement of the pendulum and in 1657 or 1658, he began to improve on pendulum mechanisms, studying the work of Riccioli, and going on to study both gravitation and the mechanics of timekeeping. Hooke recorded that he conceived of a way to determine longitude (then a critical problem for navigation), 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, fitted with a coil spring attached to the arbour of the balance. Hooke's ultimate failure to secure sufficiently lucrative terms for the exploitation of this idea resulted in its being shelved, and evidently caused him to become more jealous of his inventions. There is substantial evidence to state with reasonable confidence, as Ward, Aubrey, Waller and others all do, that at the very least Hooke developed the spring escapement independently of and some fifteen years before Huygens, who published his own work in Journal de Scavans in February of 1675. Henry Sully, writing in Paris in 1717, described the watch escapement as "an admirable invention of which Dr. Hooke, formerly professor of geometry in Gresham College at London, was the inventor." Derham also attributes it to Hooke.
The Royal Society was founded in 1660, and in April 1661 the society debated a short tract on the rising of water in slender glass pipes, in which Hooke reported that the height water rose was related to the bore of the pipe (due to what is now termed capillary action). His explanation of this phenomenon was subsequently published in Micrography Observ. issue 6, in which he also explored the nature of "the fluidity of gravity". On November 5, 1661, Sir Robert Moray proposed that a Curator be appointed to furnish the society with Experiments, and this was unanimously passed with Hooke being named. His appointment was made on 12 November, with thanks recorded to Dr. Boyle for releasing him to the Society's employment.
In 1664, Sir John Cutler settled an annual gratuity of fifty pounds on the Society for the founding of a Mechanick Lecture, and the Fellows appointed Hooke to this task. On June 27 1664 he was confirmed to the office, and on 11 January 1665 was named Curator by Office for life with an additional salary of £30 to Cutler's annuity.
Hooke's role at the Royal Society was to demonstrate experiments from his own methods or at the suggestion of members. Among his earliest demonstrations were discussions of the nature of air, the implosion of glass bubbles which had been sealed with comprehensive hot air, and demonstrating that the Pabulum vitae and flammae were one and the same. He also demonstrated that a dog could be kept alive with its thorax opened, provided air was pumped in and out of its lungs, and noting the difference between venous and arterial blood. There were also experiments on the subject of gravity, the falling of objects, the weighing of bodies and measuring of barometric pressure at different heights, and pendulums up to 200 ft long.
Instruments were devised to measure a second of arc in the movement of the sun or other stars, to measure the strength of gunpowder, and in particular an engine to cut teeth for watches, much finer than could be managed by hand, an invention which was, by Hooke's death, in constant use.
In 1663 and 1664 Hooke produced his microscopical observations, subsequently collated in Micrographia in 1665.
On March 20, 1664, Hooke succeeded Arthur Dacres as Gresham Professor of Geometry. Hooke received the degree of "Doctor of Physic" in December, 1691.
The publication of Hooke's diary in 1935 revealed other sides of the man that 'Espinasse, in particular, has detailed carefully. She writes that "the picture which is usually painted of Hooke as a morose and envious recluse is completely false.". Hooke interacted with noted craftsmen such as Thomas Tompion, the clockmaker, and Christopher Cocks (Cox), an instrument maker. Hooke met often with Christopher Wren, with whom he shared many interests, and had a lasting friendship with John Aubrey. Hooke's diaries also make frequent reference to meetings at coffeehouses and taverns, and to dinners with Robert Boyle. He took tea on many occasions with his lab assistant, Harry Hunt. Within his family, Hooke took both a niece and a cousin into his home, teaching them mathematics.
Robert Hooke spent his life largely on the Isle of Wight, at Oxford, and in London. He never married, but his diary shows that he was not without affections, and more, for others. On 3 March 1703, Hooke died in London, having amassed a sizable sum of money, which was found in his room at Gresham College. He was buried at St Helen's Bishopsgate, but the precise location of his grave is unknown.
There is little doubt that Hooke was prone to intellectual jealousy. His disputes with Newton over credit for work on gravitation and the planets, and with Oldenburg over credit for the watch escapement, are but two well-known examples, and he was apt to use ciphers and guard his ideas. As curator of Experiments to the Royal Society he was responsible for demonstrating many ideas sent in to the Society, and there is evidence that he would subsequently assume some credit for these ideas. Hooke also was immensely busy and thus unable – or in some cases unwilling, pending a way of profiting from the enterprise via letters patent – to develop all of his own ideas. This was a time of immense scientific progress, and numerous ideas were developed in several places simultaneously.
None of this should distract from Hooke's inventiveness, his remarkable experimental facility, and his capacity for hard work. His ideas about gravitation, and his claim of priority for the inverse square law, are outlined below. He was granted a large number of patents for inventions and refinements in the fields of elasticity, optics, and barometry. The Royal Society's Hooke papers (recently discovered after disappearing when Newton took over) will open up a modern reassessment.
In 1660, Hooke discovered the law of elasticity which bears his name and which describes the linear variation of tension with extension in an elastic spring. He first described this discovery in the anagram "ceiiinosssttuv", whose solution he published in 1678 as "Ut tensio, sic vis" meaning "As the extension, so the force." Hooke's work on elasticity culminated, for practical purposes, in his development of the balance spring or hairspring, which for the first time enabled a portable timepiece - a watch - to keep time with reasonable accuracy. A bitter dispute between Hooke and Christiaan Huygens on the priority of this invention was to continue for centuries after the death of both; but a note dated 12 June 1670 in the Hooke Folio (see External links below), describing a demonstration of a balance-controlled watch before the Royal Society, has been held to favour Hooke's claim.
Hooke became Curator of Experiments in 1662 to the newly founded Royal Society, and took responsibility for experiments performed at its weekly meetings. This was a position he held for over 40 years. While this position kept him in the thick of science in Britain and beyond, it also led to some heated arguments with other scientists, such as Huygens (see above) and particularly with Isaac Newton and the Royal Society's Henry Oldenburg. In 1664 Hooke also was appointed Professor of Geometry at Gresham College in London and Cutlerian Lecturer in Mechanics.
On 8 July 1680, Hooke observed the nodal patterns associated with the modes of vibration of glass plates. He ran a bow along the edge of a glass plate covered with flour, and saw the nodal patterns emerge.
While many of his contemporaries believed in the aether as a medium for transmitting attraction or repulsion between separated celestial bodies, Hooke argued for an attracting principle of gravitation in Micrographia of 1665. Hooke’s 1666 Royal society lecture “On gravity” added two further principles - that all bodies move in straight lines till deflected by some force and that the attractive force is stronger for closer bodies. Hooke’s 1670 Gresham lecture explained that gravitation applied to “all celestiall bodys” and added the principles that the gravitating power decreases with distance and that in the absence of any such power bodies move in straight lines.
Hooke published his ideas about the "System of the World" again in somewhat developed form in 1674, as an addition to "An Attempt to Prove the Motion of the Earth from Observations". Hooke announced in 1674 that he planned to "explain a System of the World differing in many particulars from any yet known", based on three "Suppositions": that "all Coelestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers" [and] "they do also attract all the other Coelestial Bodies that are within the sphere of their activity"; that "all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a straight line, till they are by some other effectual powers deflected and bent..."; and that "these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers". Thus Hooke clearly postulated mutual attractions between the Sun and planets, in a way that increased with nearness to the attracting body.
Hooke's statements up to 1674 made no mention, however, that an inverse square law applies or might apply to these attractions. Hooke's gravitation was also not yet universal, though it approached universality more closely than previous hypotheses. Hooke also did not provide accompanying evidence or mathematical demonstration. On these two aspects, Hooke stated in 1674: "Now what these several degrees [of gravitational attraction] are I have not yet experimentally verified" (indicating that he did not yet know what law the gravitation might follow); and as to his whole proposal: "This I only hint at present", "having my self many other things in hand which I would first compleat, and therefore cannot so well attend it" (i.e. "prosecuting this Inquiry").
In November 1679, Hooke initiated a remarkable exchange of letters with Newton (of which the full text is now published). Hooke's ostensible purpose was to tell Newton that Hooke had been appointed to manage the Royal Society's correspondence. Hooke therefore wanted to hear from members about their researches, or their views about the researches of others; and as if to whet Newton's interest, he asked what Newton thought about various matters, giving a whole list, mentioning "compounding the celestial motions of the planetts of a direct motion by the tangent and an attractive motion towards the central body", and "my hypothesis of the lawes or causes of springinesse", and then a new hypothesis from Paris about planetary motions (which Hooke described at length), and then efforts to carry out or improve national surveys, the difference of latitude between London and Cambridge, and other items. Newton's reply offered "a fansy of my own" about a terrestrial experiment (not a proposal about celestial motions) which might detect the Earth's motion, by the use of a body first suspended in air and then dropped to let it fall. The main point was to indicate how Newton thought the falling body could experimentally reveal the Earth's motion by its direction of deviation from the vertical, but he 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 how the body would continue to move. A short further correspondence developed, and towards the end of it Hooke, writing on 6 January 1679|80 to Newton, communicated his "supposition ... that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall, and Consequently that the Velocity will be in a subduplicate proportion to the Attraction and Consequently as Kepler Supposes Reciprocall to the Distance." (Hooke's inference about the velocity was actually incorrect.)
In 1686, when the first book of Newton's 'Principia' was presented to the Royal Society, Hooke claimed that Newton had had from him the "notion" of "the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the Center". At the same time (according to Edmond Halley's contemporary report) Hooke agreed that "the Demonstration of the Curves generated therby" was wholly Newton's.
A recent assessment about the early history of the inverse square law is that "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". Newton himself had shown in the 1660s that for planetary motion under a circular assumption, force in the radial direction had an inverse-square relation with distance from the center. Newton, faced in May 1686 with Hooke's claim on the inverse square law, denied that Hooke was to be credited as author of the idea, giving reasons including the citation of prior work by others before Hooke. Newton also firmly claimed that even if it had happened that he had first heard of the the inverse square proportion from Hooke, which it had not, he would still have some rights to it in view of his mathematical developments and demonstrations, which enabled observations to be relied on as evidence of its accuracy, while Hooke, without mathematical demonstrations and evidence in favour of the supposition, could only guess (according to Newton) that it was approximately valid "at great distances from the center".
On the other hand, Newton did accept and acknowledge, in all editions of the 'Principia', that Hooke (but not exclusively Hooke) had separately appreciated the inverse square law in the solar system. Newton acknowledged Wren, Hooke and Halley in this connection in the Scholium to Proposition 4 in Book 1. Newton also acknowledged to Halley that his correspondence with Hooke in 1679-80 had reawakened his dormant interest in astronomical matters, but that did not mean, according to Newton, that Hooke had told Newton anything new or original: "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 ...".)
One of the contrasts between the two men was that Newton was primarily a pioneer in mathematical analysis and its applications as well as optical experimentation, while Hooke was a creative experimenter of such great range, that it is not surprising to find that he left some of his ideas, such as those about gravitation, undeveloped. This in turn makes it understandable how 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, made his assessment after reviewing what Hooke had published on gravitation. "One must not think that this idea ... of Hooke diminishes Newton's glory", Clairaut wrote; "The example of Hooke" serves "to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated".
In 1665 Hooke published Micrographia, a book describing his microscopic and telescopic observations, and some original work in biology. Hooke coined the term cell for describing biological organisms, the term being suggested by the resemblance of plant cells to monks' cells. The hand-crafted, leather and gold-tooled microscope he used to make the observations for Micrographia, originally constructed by Christopher White in London, is on display at the National Museum of Health and Medicine in Washington, DC.
Micrographia also contains Hooke's, or perhaps Boyle and Hooke's, ideas on combustion. Hooke's experiments led him to conclude that combustion involves a substance that is mixed with air, a statement with which modern scientists would agree, but that was not widely understood, if at all, in the seventeenth century. Hooke went on to conclude that respiration also involves a specific component of the air. Partington even goes so far as to claim that if "Hooke had continued his experiments on combustion it is probable that he would have discovered oxygen".
One of the more-challenging problems tackled by Hooke was the measurement of the distance to a star (other than the Sun). The star chosen was Gamma Draconis and the method to be used was parallax determination. After several months of observing, in 1669, Hooke believed that the desired result had been achieved. It is now known that Hooke's equipment was far too imprecise to allow the measurement to succeed. Gamma Draconis was the same star William Bradley used in 1725 in discovering the aberration of light.
Hooke's activities in astronomy extended beyond the study of stellar distance. His Micrographia contains illustrations of the Pleiades star cluster as well as of lunar craters. He performed experiments to study how such craters might have formed. Hooke also was an early observer of the rings of Saturn, and discovered one of the first double-star systems, Gamma Arietis, in 1664.
Hooke achieved fame in his day as Surveyor to the City of London and chief assistant of Christopher Wren. Hooke helped Wren rebuild London after the Great Fire in 1666, and also worked on designing London's Monument to the fire, the Royal Greenwich Observatory, Montagu House in Bloomsbury, and the infamous Bethlem Royal Hospital (which became known as 'Bedlam'). Other buildings designed by Hooke include The Royal College of Physicians (1679), Ragley Hall in Warwickshire, and the parish church at Willen in Milton Keynes, Buckinghamshire. Hooke's collaboration with Christopher Wren also included St Paul's Cathedral, whose dome uses a method of construction conceived by Hooke.
In the reconstruction after the Great Fire, Hooke proposed redesigning London's streets on a grid pattern with wide boulevards and arteries, a pattern subsequently used in the renovation of Paris, Liverpool, and many American cities. This proposal was thwarted by arguments over property rights, as property owners were surreptitiously shifting their boundaries. Hooke was in demand to settle many of these disputes, due to his competence as a surveyor and his tact as an arbitrator.
For an extensive study of Hooke's architectural work, see the book by Cooper.
No authenticated portrait of Robert Hooke exists, a situation sometimes attributed to the heated conflicts between Hooke and Isaac Newton. In Hooke's time, the Royal Society met at Gresham College, but within a few months of Hooke's death Newton became the Society's president and plans were laid for a new meeting place. When the move to new quarters finally was made a few years later, in 1710, Hooke's Royal Society portrait went missing, and has yet to be found.
Time magazine published a portrait, supposedly of Hooke, in its 3 July 1939 issue. However, when the source was traced by Ashley Montagu, it was found to lack a verifiable connection to Hooke. Moreover, Montagu found that contemporary written descriptions of Hooke's appearance agreed with one another, but that neither matched Times alleged picture of him. In 2003, historian Lisa Jardine claimed that a recently-discovered portrait was of Hooke, but this claim was disproved by William Jensen of the University of Cincinnati. The portrait identified by Jardine, in fact, depicts the Flemish scholar Jan Baptist van Helmont. Other possible likenesses of Hooke include the following:
In 2003 history painter Rita Greer embarked on a self-funded project to memorialize Hooke. The Rita Greer Robert Hooke project aimed to produce credible images of him, both painted and drawn, that fitted his contemporary descriptions drawn from two sources: John Aubrey and Richard Waller. Greer's images of Hooke, his life and work have been used for TV programmes in UK and USA, in books, magazines and for PR.
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