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Hooke, Robert (1635–1703), natural philosopher, was born on 18 July 1635 in the village of Freshwater on the Isle of Wight, the son of the Revd John Hooke (d. 1648), minister of the parish, and his wife, Cecily Gyles (d. 1665). According to some autobiographical notes reported by Richard Waller in The Posthumous Works of Robert Hooke (1705), young Robert's constitution was so weak and sickly that his parents feared for his life for at least his first seven years. He was nursed at home, in contrast to his brother and sisters who were nursed abroad. Hooke reports himself to have been sprightly and active in running and leaping, though incapable of more robust exercise. His quick capacity to learn initially led his father to instruct him towards the ministry, but young Hooke's severe headaches interfered with his studies and this plan was abandoned. Left to his own interests, he constructed mechanical toys and devices, including a wooden clock ‘that would go’ and a ship model about a yard long complete with rigging and some small guns that could fire as it sailed. He also exhibited talent in drawing.

Robert Hooke's father died in October 1648. John Aubrey reports in his Brief Lives that the thirteen-year-old Robert received an inheritance of £100, but according to the actual will Robert's inheritance amounted to £50 (including £10 from Robert's grandmother on his mother's side) and all his father's books (Nakajima). Hooke was sent to London to study with the painter Sir Peter Lely, his inheritance used to secure his apprenticeship. Waller reports that the smell of the oil paints increased Hooke's headaches, curtailing this activity, while Aubrey ascribes the brevity of this association to young Hooke's conclusion that he could teach himself this art and save the apprentice fee. Aubrey adds that Hooke also received instruction in drawing from Samuel Cowper. Hooke subsequently went to live in the house of Richard Busby, master of Westminster School. Though he attended school infrequently, he actively pursued his education, learning Latin and Greek and gaining an acquaintance with Hebrew and with oriental languages. By Aubrey's account, Hooke mastered the first six books of Euclid in a week and ‘learned to play twenty lessons on the organ’, which presumably means that he learned to play the organ in twenty lessons.

Introduction to science

In 1653 or 1654 Hooke went to Christ Church, Oxford, where his musical training was sufficient to secure the post of chorister. He served as assistant to the chemist Thomas Willis and subsequently to Robert Boyle. Working for Boyle, Hooke was exposed to active scientific research: he was responsible for Boyle's first workable pneumatic engine (vacuum pump) and assisted Boyle in his experiments on the spring and weight of the air. At Oxford, Hooke was brought into contact with many other of the finest natural philosophers of the day, including John Wilkins, Seth Ward, William Petty, John Wallis, and Christopher Wren. Among his scientific endeavours there were the pursuit of astronomy and, instigated by Ward, the development of clockwork for recording observations. Hooke later ascribed his invention of a spring-regulated watch to this time. He did not receive a bachelor's degree, but was granted his MA degree in 1663.

In November 1662 Hooke was formally proposed as curator of experiments for the newly formed Royal Society of London, his task being to provide three or four experiments at each meeting [see ]. This post was to be without recompense until the society could afford to provide a salary. Hooke lost no time in fulfilling his responsibilities, producing his first set of experiments before the society on 18 November. While not always providing the full complement of three or four experiments at every meeting, he almost invariably presented some demonstration or commentary. The value of this activity was soon recognized by the council of the Royal Society, which included Hooke on its list of 20 May 1663 of persons to be admitted as fellows.

The range of Hooke's demonstrations and commentaries in this early period was remarkable. Indeed, virtually all his later publications had their roots in work performed at this time, in enquiries which Hooke would address and then put aside, sometimes repeatedly over the years. These various endeavours were recorded week by week in the journal books of the Royal Society and eventually printed in Thomas Birch's History of the Royal Society of London (1757). In these volumes, as well as in the many brief references in Hooke's diaries (in the London Guildhall Library), Hooke addresses very different areas of science from week to week, day to day, and even within a single day. While his published accounts in the Micrographia, in his Cutler lectures, and in various articles, appear successively over many years, his actual practice involved a more complicated diversity of simultaneous endeavours. This diversity is even more remarkable given his responsibilities in the years following the great fire of London of 1666 as one of the official surveyors for the rebuilding.

Hooke's employment with the Royal Society gained him respect in the scientific community but his post continued to be without remuneration. An opportunity for a salaried position presented itself in 1664 with the resignation of Isaac Barrow as professor of geometry of Gresham College. On 20 May the committee for the college met to decide on Barrow's replacement, selecting Arthur Dacres over Hooke. A month later, a delegation from the Royal Society was ordered to speak to Sir John Cutler about his promise to pay £50 a year for life to Mr Hooke to lecture at Gresham College on the histories of trades. A formal statement of Hooke's appointment to the Cutler lectureship was made before the Royal Society on 9 November. The next week Hooke was proposed as ‘curator by office’ to the society, a salaried position corresponding to the volunteer post he had been holding. Although the council had decided some months previously on a yearly salary of £80 for the curator, this now became £30 in view of the £50 per year to be supplied by Cutler. This appointment in effect makes Hooke the first professional research scientist, employed specifically to enquire into the phenomena and principles of nature. On the other hand, as a salaried employee, distinct from the many volunteer curators for specific experiments drawn from the other fellows of the society, Hooke's social position was in principle one of servant. Thus he was frequently ‘ordered’ to try an experiment or to bring in an account, whereas other members of the society were ‘desired’ to carry out corresponding tasks. Hooke was, however, so successful in his experimental pursuits that within a couple of years he had made himself indispensable, and for the most part was allowed to determine his own experimental programme.

The Philosophical history

Hooke moved into Gresham College in September or October 1664 to lecture on the history of nature and art under the endowment provided by Cutler. Francis Bacon had insisted throughout his works that a history of nature was a necessary prerequisite to the formulation of a new natural philosophy. In his New Atlantis (1627) Bacon imagined an organization, ‘Salomon's House’, that would carry out this programme. To many of its early members the Royal Society was a realization of Salomon's House, and Hooke's promotion of a new natural history through his lectures was therefore an appropriate activity. Some of his ideas for this new natural philosophy are found in a series of manuscripts which are probably the texts of these early lectures (London, Guildhall Library, MS 1757/11; RS, classified papers 20.50a, 50b).

For Hooke as for Bacon the improvement of natural philosophy must rest on a suitably collected and arranged body of knowledge which Hooke calls the ‘Philosophical history’. He divides the subjects of this history into art or trades versus natural phenomena, with the latter further divided and subdivided. Each investigation into a specific phenomenon is to be guided by an extended series of queries, the order of which serves to organize the observations being recorded. Should observations be found to favour contrary hypotheses, further queries are required to reach an ‘experimentum crucis’ sufficient to decide between the alternatives. Both here, and when he uses this term in the Micrographia, Hooke attributes this phrase to Francis Bacon. While Bacon presents in his Novum organum the idea of observations intended to distinguish between different supposed causes, he refers to these as ‘instantias crucis’. The specific phrase ‘experimentum crucis’, best known for its use by Isaac Newton in his 1672 letter a ‘New theory about light and colours’, appears to have originated with Hooke.

Hooke elaborates upon Bacon's views on spreading among many investigators the work of compiling the history of nature and art. His list of qualifications for the ‘Philosophical historian’ provides insight into the body of learning he presumably hoped to attain. The historian must have a knowledge of mechanics and other mathematical learning and must have experience in experimental procedures and in the techniques of various trades. Since these last would be difficult for any one person to gain first hand, Hooke proposes that detailed accounts of specific trades be collected, an effort to which he himself made several contributions over the ensuing years. He suggests that the techniques of the tradesmen themselves could benefit from the careful scrutiny of capable men not already set in the established procedures of that trade. He expects his historian to be familiar with the full range of current explanatory hypotheses and theories, but free from dogmatic adherence to any of them. The historian ought to repeat all experiments and observations at least two or three times, describing his instruments and manner of experimenting as well as recording the observations themselves.

The ideas presented in these lectures are restated in more polished form in Hooke's posthumously published essay ‘A general scheme, or idea of the present state of natural philosophy, and how its defects may be remedied by a methodical proceeding in the making experiments and collecting observations, whereby to compile a natural history, as the solid basis for the superstructure of true philosophy’ (Hooke, 1–70). This essay stands as the most compelling rendition of Baconian principles into a solid programme of scientific investigation.

The Philosophical algebra

Shortly after arriving at Gresham College, Hooke learned of an irregularity in the election which he had lost the year before. According to John Ward's manuscript ‘Memoires relating to Gresham College’, Hooke petitioned the college committee about this on 20 March 1665. The committee found that of the ten men present at the election the previous May, five had voted for Hooke and five for Dacres. Among this second group was the lord mayor, who then used his tie-breaking vote to declare the election in Dacres's favour. Since, however, the lord mayor was not actually a member of the committee and should not have voted unless there was a tie, Hooke had actually won the election by five votes to four, as was now recognized; he duly ascended to the geometry lectureship of Gresham College in June.

In both his lecture series of 1665 and his ‘General scheme’ of 1668, Hooke promises to provide a ‘Philosophical algebra’ or method for raising general principles of nature from the philosophical history. While he does not deliver on this promise, leaving the ‘General scheme’ unfinished, he does, however, provide hints about the nature of this method, claiming that it would bring to the study of nature the benefits which mathematical algebra brings to geometry. These last benefits are treated in detail by Hooke in a series of Latin manuscripts in the London Guildhall Library and in the English translation of one of these at the Royal Society (London, Guildhall Library, MS 1757/12; RS, classified papers 20.39). The Royal Society manuscript is dated June 1665, and the lectures show a smooth transition from his previous lectures on the philosophical history to a more mathematical topic fitting his new position.

In these lectures Hooke represents geometry and arithmetic as the studies of continuous and discontinuous quantities, respectively. Algebra is introduced, not as a third field of mathematics, but as an ancillary means of solving problems in geometry and arithmetic. For Hooke the power of algebra is that it facilitates the procedures of ‘comparing, compounding and separating’ elements of a problem leading towards the discovery of a solution. Algebra achieves this by:
comprising in a small space a whole series of ratiocination so, as to a small cast of an eye as it were, and in an instant almost, one is enabled to examine and compare and change and transpose and order any part of it, as he pleases, with very little trouble and the greatest certainty. (RS, classified papers 20.39, fol. 65v)
Hooke suggests that problems in the understanding of nature could likewise be solved if these same advantages were available to natural philosophy.

Near the end of the ‘General scheme’, after advocating the use of simple language in registering natural histories, Hooke suggests recording philosophical histories in a shorthand or abbreviated form. As in mathematical algebra, the use of ‘obvious and plain symbols’ is to help the mind to reach new insights in natural philosophy. Hooke's ideas in this area reflect the influence of Ward and Wilkins, his acquaintance with whom had carried on from Oxford to the Royal Society. These two scholars advocated the formulation of a universal character as part of a universal language, intended to replace Latin as the language of international communication. Ward and Wilkins, however, felt that this language should have a logical structure such that the words or symbols for objects and relations would reflect the essence of the things being represented. Hooke was much in contact with Wilkins during the years when the latter was composing An Essay towards a Real Character and a Philosophical Language (1668). Samuel Pepys mentions in his diary entry for 4 June 1666 that Hooke accompanied him home from Gresham College and borrowed some tables of nautical terms for Wilkins's book. Hooke praises Wilkins's invented language at the end of his Cutler lecture on helioscopes (1676) and prints a description of the principle of his spring-regulated watch in Wilkins's Real Character. Some years later Leibniz and Hooke engaged in a correspondence in which the former expresses views remarkably similar to Hooke's about the inventive power of a well-conceived set of symbols for representing objects and relations in nature. Hooke's statements within that correspondence exactly parallel his earlier claims for the philosophical algebra:
My aims have always been much higher, viz. to make it not only useful for expressing and remembering of things and notions but to direct, regulate, assist and even necessitate and compel the mind to find out and comprehend whatsoever is knowable. (RS, early letters, H.3.64)

The Micrographia

Hooke's ideas about the collecting of observations of nature and art and the philosophical understanding to be adduced from them are exemplified in his most famous work, Micrographia, or, Some physiological descriptions of minute bodies made by magnifying glasses, with observations and inquiries thereupon (1665). This book initiated the field of microscopy. Just as Galileo, on turning his telescope to the heavens, had made one remarkable observation after another, so Hooke, applying his microscope to inanimate and animate objects, revealed equally remarkable features about their structure. His talent for drawing and attention to detail is evident in the many plates that adorn the volume, especially those of the fly, gnat, and flea. His text provides clear and precise descriptions of observations, but also provides explanations of the things observed. A description ‘Of the colours observable in muscovy glass [mica], and other thin bodies’ serves as an introduction to a lengthy discussion of his two-colour (blue and red) theory of light. According to this theory, light is a motion transmitted through a medium, the source of which is the rapid vibration of the minute parts of the shining body. This vibration produces pulses in the surrounding medium which, according to Hooke, may be oblique to the line of propagation. If this obliqueness results in the weaker side or edge of the pulse arriving before the stronger, then the light registers on the eye as blue; if the stronger side precedes the weaker, then the light appears red. While Hooke's theory contains many ambiguous features, it does allow him to explain how white light can become coloured through refraction in prisms and through refraction and reflection in thin plates.

Hooke's observations of kidney stones and of crystals found in flint lead to a discussion of the regular form of crystals and the way these can arise from arrangements of tightly packed spherical particles. In his observations of petrified wood, Hooke notes the presence of small regular compartments which he terms cells, thereby introducing that term into the biological sciences. In his observations of cork he elaborates on his description of cells, ascribing to them a diameter of less than a thousandth of an inch. In treating fossils he proposes a process by which once living substances fossilize, thereby setting the stage for his later geological speculations in which fossils serve as a record of past life.

Observations of charcoal lead to a general discussion of combustion. Hooke contends that there is no element of fire present in combustible objects, but rather that combustion is a process in which a substance mixed in the air combines with some part of the combustible material. While Hooke does not discuss respiration in the Micrographia, his later treatments of this subject refer to the same substance in the air as being required for respiration. His experiments in this area came to include attempts to keep a vivisected dog alive by blowing air into its lungs with a bellows. In 1668 he showed that a bird remained healthy in a container of compressed air longer than in the same volume of common air, as does a burning lamp. Hooke later engaged in some experiments involving a large chamber in which he placed himself. He reports that the evacuation of a quarter of the air in the chamber caused him to experience pain in his ears and to become temporarily deaf, but that he suffered no other ill effects.

Hooke describes the glass drops (formed by dropping molten glass into cold water) which shatter entirely when their stems are broken. This leads him to a general discussion of heat, which he regards as arising from the agitation of the parts of a body. Greater agitation results in expansion or, as in the case of water heated in a sealed container, in a tendency to expand which can cause the container to burst. Hooke describes his work with sealed thermometers and his introduction of a scale with zero corresponding to the freezing point of distilled water.

Hooke includes in the Micrographia descriptions of a variety of instruments that he has recently invented. He describes the wheel barometer and a device based on the beard of a wild oat attached to a dial to register humidity in the air. He describes a device for measuring the refraction of light passing through a transparent liquid, which instrument he reports having used to verify the law of refraction that had been published by Descartes. He also proposes a design, making clear that he has not yet built it, for a device for grinding lenses of large diameter and long focal length. Large lenses of long focal length are ideal for astronomical telescopes, though the suspension of long telescopes presents considerable difficulties. Hooke does not address this last problem in the Micrographia, but he subsequently devises a system of braces for suspending long telescopes, and has one of 40 foot length constructed in the Gresham College quadrangle. In the late 1670s Hooke describes an aerial telescope in which object lens and eyepiece are aligned by a rope and pulley, without the need for a massive tube and support. The final sections of the Micrographia deal with astronomical observations of stars and of the surface of the moon; over the course of his career he also made observations of the large spot on Jupiter, of the rotation of Mars, of double stars, and other astronomical phenomena reported in his Cutler lectures and in the Philosophical Transactions of the Royal Society.

In the Micrographia Hooke provides a calculation of the height of the atmosphere based on the inverse relation between pressure and volume of gases, a relation now known as Boyle's law. Hooke had been Boyle's assistant at the time Boyle published this relation in A Defence of the Doctrine Touching the Spring and Weight of the Air (1662). Boyle acknowledges that Richard Towneley had originally suggested this relation, but his account suggests that Towneley had not produced an experimental verification of the relation. Boyle supplies this demonstration with two experiments involving the compression and rarefaction of a sample of air by a column of mercury. A question exists of the degree to which Hooke deserves credit for the design and execution of these experiments. In the Micrographia he uses the first person in describing the same experiments. He credits Towneley with having originally suggested the hypothesis, but refers to ‘the most illustrious and incomparable Mr. Boyle’ only in connection with the value for the density of the air near the earth's surface. Hooke would hardly have failed to give more credit to Boyle for the demonstration of this hypothesis if he had felt that Boyle, or other members of the Royal Society, would find fault with the present version, and in fact was not criticized at the meetings following publication of the Micrographia. Years later Newton, who was always reticent about crediting Hooke, ascribes to Hooke the demonstration of this relation (Cohen, ‘Newton, Hooke and “Boyle's law”’, 620).

Hooke as surveyor

Hooke's financial situation improved considerably as a result of the fire of London in 1666. Less than a week after it had ceased he produced before the Royal Society a model for the rebuilding of the destroyed portion of the city. While his grid-work plan was not adopted, Hooke was made one of three official surveyors for the rebuilding, which lasted decades. Recent studies of his detailed activity in this capacity reveal no evidence that Hooke was anything but perfectly scrupulous and responsible in all of his duties (Cooper). His contributions to the rebuilding included acting as architect on a number of projects, some of which have traditionally been associated with Christopher Wren. The most notable of these (and the only one still standing) was the monument to the great fire, a particular feature of which is the open interior column which Hooke hoped to use for a variety of experimental researches. Some of these experiments were carried out, but vibrations from nearby traffic precluded many others. Another such building was the Royal College of Physicians on Warwick Lane which survived well into the nineteenth century. Hooke was also responsible for Bethlem Hospital in Moorfields, a building that was much admired until it was pulled down in 1814. Hooke's involvement with a variety of other well-known building is more ambiguous, largely because it is difficult to separate out his involvement as surveyor.

The Cutler lectures

A decade after the publication of the Micrographia Hooke began publishing a series of tracts based on lectures delivered at Gresham College before the Royal Society under Cutler's endowment. In An Attempt to Prove the Motion of the Earth by Observation (1674) he describes the fixed zenith telescope he had mounted in his lodgings at Gresham College, with which he had attempted to measure a shift in position of the brightest star of the constellation Draco over the course of the year as a demonstration of the earth's motion round the sun. While his measurements were later called into question, his method was universally praised and served as both instigation and model for the later measurements of Samuel Molyneux and James Bradley. Hooke ends this lecture with a promise to publish an account of the system of the world based upon three suppositions of celestial mechanics: first, that all celestial bodies have a gravitating power towards their centre whereby they attract not only parts of their own bodies, but also all other celestial bodies ‘within the sphere of their activity’; second, that all moving bodies travel in straight lines unless their path is deflected into a circle, ellipse, or other curve; third, that the attractive power diminishes with distance from a body's centre.

In Animadversions on the … Machina Coelestis of … Johannes Hevelius (1674), Hooke argues for the advantages of telescopic sights over plain sights for making astronomical measurements. He was not the first inventor of the micrometer for telescopic use, nor ever claimed to be, but he did invent a form of this device that received particular praise from the Royal Society. He describes in detail a split-image mural quadrant in which a pair of telescopes with sites mounted to a frame may be used to measure angles between astronomical objects. This quadrant features a spirit level so that altitudes may be measured accurately from the horizontal. Hooke describes this level in detail, apparently unaware that Thevenot had anticipated him in its invention. Hooke describes an alternative level, explicitly crediting Wren as its inventor. He devises what may have been the first dividing engine for graduating the limb of his quadrant by a screw. He also describes an equatorial mount driven by clockwork and regulated by a conical pendulum. While this is probably the earliest description of a clockwork-driven telescope, there is no evidence that it was ever constructed. Hooke also describes a quadrant mounted on a platform to which rotary motion is transmitted by another of Hooke's inventions, the universal joint.

In A Description of Helioscopes and some other Instruments (1676) Hooke describes a series of telescopes in which the path of light is folded within the telescope tube by means of one or more flat mirrors. He discusses the common flaws of mirrors for astronomical purposes and his experiments to improve them. Though the universal joint had figured in his previous lecture, he now elaborates on its various applications, and in a postscript promises to publish a theory of elasticity or springiness, presenting its key principle in the form of an anagram: ‘ceiiinosssttuu’. The promised tract is his Lectures de potentia restitutiva, or of spring (1678), where he reveals the meaning of this anagram to be ‘Ut tensio sic vis’. This principle, that a spring's extension or displacement from its neutral position is directly proportional to the force applied, has come to be known as Hooke's law. Hooke establishes this principle experimentally for a variety of configurations of springs and springy bodies. A corresponding anagram is revealed as ‘Ut pondus sic tensio’: the weight is proportional to the extension. This is the principal of another Hooke invention which he called the ‘philosophical scale’—today's spring balance.

A major premise of the mechanistic philosophers of the seventeenth century was that natural phenomena are to be explained in terms of matter and motion, and that so-called occult qualities such as nature's abhorrence of a vacuum are to be dismissed. Hooke had assisted Boyle in experiments that had gone far towards banishing from the science of pneumatics such occult principles. For Hooke the key motion to the understanding of a wide range of natural phenomena is that of vibration. In Lectures de potentia restitutiva he suggests that the vibrations of the smallest parts of matter account for the overall volume of objects. He is not specific about the details, but the different rates at which the parts of different substances vibrate give rise to a greater or lesser tendency of these parts to pack together, a phenomenon he referred to as the congruity and incongruity of different kinds of matter. Although not mentioned in this lecture, he believed that gravity might be caused by vibrations of a surrounding ether impelling one gross body towards another. He demonstrated using water in vessels and powder on plates how imparted vibrations can cause bodies to be attracted towards the source of the vibration. In the course of these and related experiments Hooke anticipated Chialdni's experiments in the visualization of vibrating modes of vessels and plates. In other experiments involving vibration and sound he anticipated Savart in the production of tones by the rotation of a toothed wheel.

The spring-regulated watch

Among Hooke's most notable inventions was the idea of using a balance wheel vibrating by the action of a spring to regulate portable timekeepers. Like a swinging pendulum, a vibrating spring has the feature that the period of oscillation is the same over a wide range of sizes of oscillation. In his lecture Of Spring he presents a theoretical analysis of the motion of a released spring intended to show that it had this property; but the analysis is flawed. While Hooke never published a corrected version, he did compose one which is preserved in manuscript in the library of Trinity College, Cambridge (MS 0.11 a.1/16).

In the same postscript to Helioscopes in which he published his anagram on springs Hooke presented his case for having invented the spring-regulated watch:
About seventeen years since [that is, about 1659], being very inquisitive about the regulating the measure of Time, in order to find the Longitude, I did from an Art of Invention, or mechanical Algebra (which I was then Master of) find out and perfect this contrivance, both as to the Theory and Experimental verification thereof, of which I then discoursed to divers of my Friends, but concealed the modus. (Gunther, Cutler Lectures, 146)
There was apparently no working model. Waller confirms having seen a draft of an agreement with Lord Brouncker, Robert Boyle, and Sir Robert Moray guaranteeing Hooke an income in return for revealing his invention. According to Hooke's account, negotiations broke down over a clause that would have denied to him any benefit of his invention should anyone else improve the device. He was aware that there were a large variety of ways that springs could be applied to regulate timekeepers, and that any of these could be regarded as improvements for specific applications, and therefore withheld details of his invention. In January 1675 Christiaan Huygens invented the spiral balance and in February he obtained a French patent. Huygens then offered the rights of any English patent to the society but this offer was not mentioned when Oldenburg read Huygens's letter at the society meeting of 18 February 1675. Hooke protested his priority and, when he heard of the patent offer, accused Oldenburg of treachery. Thereafter the matter degenerated into a personal battle between Oldenburg and Lord Brouncker on one side and Hooke on the other, both sides seeking to obtain a patent. As part of his unsuccessful attempt Hooke had Tompion construct a presentation watch for Charles II with the engraved legend, ‘Robert Hook inven. 1658. T. Tompion fecit 1675’.

Orbital motion

Following Oldenburg's death in 1677, Hooke was elected as one of two secretaries to the Royal Society. In this capacity he initiated correspondence with a number of members who had not been heard from in recent years, among them Isaac Newton. In 1672, when Newton had submitted his ‘New theory about light and colours’ to the Royal Society, it had sparked heated debate and exchanges of letters. Hooke had been particularly critical of Newton's underlying view that light consisted of a stream of particles, though Newton had insisted that his conclusions did not depend upon that hypothesis. In spite of that earlier dispute the exchange of letters in 1677, which also dealt with the refraction of light, was thoroughly cordial.

In November 1679 Hooke again entreated Newton to communicate his thoughts on philosophical matters, inviting him to comment on Hooke's work:
And particularly if you will let me know your thoughts of that of compounding the celestiall motions of the planets of a direct motion by the tangent & an attractive motion towards the centrall body, Or what objections you have against my hypothesis of the lawes or causes of Springinesse. (Correspondence of Isaac Newton, 2.297)
Newton replied that he had not heard of these hypotheses. He proposed an experiment to detect the effects of the earth's rotation on a falling body, including a diagram in which the path of fall is extended within the body of the earth. Hooke corrected Newton's diagram only to be corrected in turn by Newton with a new diagram based on the assumption of a constant force towards the centre of the earth. Hooke replied that his own supposition was that gravitational attraction acted ‘in a duplicate proportion to the Distance from the Center Reciprocall’ (ibid., 2.309), that is, as the inverse square of distance. Given this correspondence it is not surprising that Hooke felt that Newton had learned the inverse square law of gravity from him. He could not know that over a decade earlier Newton had not only supposed this relation, but had tested it by calculation two different ways. Hooke's insistence that he deserved some credit from Newton for this proposition, and Newton's refusal to acknowledge any debt to Hooke whatsoever, led to mutual resentment that never abated. While Newton had good reason not to acknowledge a debt to Hooke for the inverse square relation, recent scholarship credits Hooke with introducing Newton to the idea of analysing orbital motion as the sum of a tangential velocity and a deflection towards a centre (Westfall; Cohen, ‘Newton's discovery’). This became a key feature of Newton's subsequent analysis of orbital motion in the tract De Motu and in the Principia (1687), while it had not figured in his earlier demonstrations on the inverse square law.

Earth sciences

In 1663 Hooke laid before the Royal Society a detailed proposal for making a history of the weather, a version of which was printed in Sprat's History of the Royal Society (1667). He invented or improved several of the instruments commonly associated with meteorology. Best known of these is the wheel barometer, for which he had at least three slightly different designs. He also developed multi-liquid barometers for increased precision, credit for which must be shared with Huygens. Hooke's so-called marine barometer (actually a manometer) was intended to serve on board a moving ship, where the mercury barometer was impractical. Other instruments devised by him include rain gauges, hygroscopes for determining the humidity of the air, and a wind speed instrument. He was also involved in the development of a weather-clock which would automatically record a number of different instrument readings. While the general Baconian goal of collecting data and raising theories from revealed correspondences did not lead to advances in weather prediction either for Hooke or for his successors in the centuries to follow, he was among the first to recognize the barometer's ability to predict storms.

Hooke's analysis of the height of the atmosphere distinguishes clearly between the two factors of height and density that contribute to the pressure of a surrounding medium. He demonstrated these two effects by immersing a mercury barometer to various depths in vessels of salt and fresh water. In an effort to focus on this second factor as it applies to the atmosphere, he produced an air poise or aerostatic balance, a device previously described by Robert Boyle and Otto Von Guericke. Hooke used the idea of variable atmospheric density, again illustrated by using fresh and salt water, to explain the floating of clouds. Among the experiments carried out by him at the Monument was a series of measurements of air pressure at various altitudes intended as a check on his analysis of the height of the atmosphere.

Following the society's declared interest in the depth and salinity of the seas and oceans, Hooke developed instruments for sounding the depths and for bringing up water from the bottom. His geological ideas are summarized in a series of tracts collected by Waller in Hooke's Posthumous Works. In 1668 he declared his conviction that fossil shells derive from once-living bodies, by no means a universal view at the time. The presence of these aquatic forms in regions now remote from the sea is explained at some length as being due to the rising from and settling into the sea of bodies of land through the action of earthquakes and, to a lesser extent, erosion by the sea and by weather. In a series of lectures delivered early in 1687, Hooke explains the major upheavals suffered by the earth in terms of the dynamics of a rotating body. Supposing the earth to have consisted originally of concentric layers of earth and water, the uneven stresses caused by its daily rotation would cause fissures as matter is forced away from the axis, most strongly near the equator, least strongly near the poles. Shifts in the axis of rotation, which Hooke believes to have taken place even in historical times, would introduce changes in the portion of the globe subject to the greatest forces. Thus, mountains may form where there had previously been seas, explaining the presence of fossil shells in mountainous regions.

Character and final years

As curator of experiments for the Royal Society, Hooke's contribution in establishing a strong role for empirical approaches to the understanding of nature was considerable. He also served the society as secretary and publisher of the Philosophical Collections, the short-lived successor to the Philosophical Transactions, in the late 1670s and early 1680s. He remained as lecturer in geometry at Gresham College until his death, residing in his rooms at the college and carrying out all duties responsibly, including during periods when other professors were failing to deliver lectures and were even renting out their rooms. The only major exception to this was between July 1665 and March 1666 when the plague was most severe in London; during this period Hooke and some others attended Wilkins in Surrey, carrying out philosophical investigations that were later reported to the Royal Society. Hooke's reputation as a natural philosopher and experimenter was widespread. In 1691 he received from the bishop of Lambeth a licence to practise medicine, in recognition of his medical enquiries into relieving his own long-term ill health, and for his earlier anatomical, physiological, and microscopic researches. Thomas Shadwell created the character of Sir Nicholas Gimcrack in his play The Virtuoso as a parody of scientific practitioners of the day, and of Hooke in particular. After attending a performance on 2 June 1676, Hooke recorded in his diary, ‘Damned Dogs. Vindica me Deus. People almost pointed’ (Robinson and Adams, 235). While Hooke was not pleased at being the object of parody, the incident shows that he was so well known that Shadwell's audience recognized him as the model.

Three charges against Hooke's character arise in accounts of his life and work. The first is that he was a ‘universal claimant’, whose response to being told of some invention or discovery was to claim to have accomplished the same work himself years before. The second is that he was miserly. The third is that he was cantankerous and had an ill-natured disposition. The first of these has some justice as there are a large number of minor cases recorded in the minutes of Royal Society meetings of exactly this taking place. There are also a small number of celebrated cases of extended disputes over priority: most notably with Huygens over the invention of the spring-regulated watch and some other devices and with Newton over the discovery of the principles of gravity and orbital motion. When the disputes are individually examined, Hooke's claims are never without foundation, though he does not always appreciate the extent to which others had progressed his ideas, or rendered them practical. Moreover, there are also cases where Hooke makes no claims even when he deserves more credit than he received. Hooke's regard for Robert Boyle, in part a measure of their great disparity in rank but probably also due to his loyalty and gratitude towards one who was so important in launching his career, precludes any hints that Boyle owed him credit for the work they had accomplished together. Halley, a junior friend of social position comparable to Hooke, is never challenged over his paper on the upward extension of the atmosphere in spite of Hooke's earlier, seminal work on this topic.

Hooke's reputation for being miserly has little foundation. After his death a chest that had been unopened for thirty years, containing several thousand pounds, was found in his rooms. Hooke presumably regarded this money, earned during the most lucrative period of his activities as surveyor, as his savings account, and lived day to day on his income. He was frugal, but no more so than one would have expected of a self-made man in a profession that was not well established. He was involved in a major law suit over money, that against the estate of John Cutler for unpaid salary under the Cutler endowment. This was but the culmination of years of difficulty in obtaining his promised salary. Hooke's initial failure to obtain the position of professor of geometry at Gresham College, in spite of having properly won the election, presumably served as an early reminder that he would obtain what was due to him only by pursuing his claims.

While Hooke's acrimonious disputes with Newton and Oldenburg have occasionally been ascribed to a cantankerous nature, he is far from alone in being on ill terms with these particular individuals. His disputes with Huygens over matters of priority become acrimonious only with respect to Hooke's belief that Oldenburg was revealing features of Hooke's work that were learned in confidence. His dispute with Hevelius is a technical one over the accuracy of plain versus telescopic sights, in the midst of which Hooke remains free in his praise of Hevelius's accomplishments. Hooke's diaries and correspondence make it clear that he had a goodly number of friends and acquaintances who were pleased to share his company at coffee houses and in his rooms. On the other hand, Hooke did suffer from a range of digestive and other maladies which placed considerable strains upon his disposition. There is no indication of the effect upon him of the death by suicide of his brother John, but Waller reports that after the death of his niece Grace (1660–1687), John's daughter, he became melancholy and cynical, and remained so until his own death (Hooke, xxiv). Grace had lived in Hooke's care at least since she was eleven, and had eventually become his mistress. (An earlier liaison with a married woman, Nell, née Young, a maid and seamstress, had ended in September 1673.)

No portrait of Hooke remains, though one is reported to have existed. Waller describes him as crooked and low of stature, though:
by his Limbs he shou'd have been moderately tall. He was always very pale and lean, and laterly nothing but Skin and Bone, with a meagre Aspect, his Eyes grey and full, with a sharp ingenious Look whilst younger; his Nose but thin, of a moderate height and length; his Mouth meanly wide, and upper Lip thin; his Chin sharp, and Forehead large; his head of middle size. He wore his own Hair of a dark brown colour, very long and hanging neglected over his Face uncut and lank, which about three Year before his Death he cut off, and wore a Periwig. (Hooke, xxvii)
Following his death on 3 March 1703 those members of the Royal Society then in London attended his burial at St Helen, Bishopsgate. His grave is not marked.

Patri J. Pugliese

Sources  

E. N. da C. Andrade, ‘“Robert Hooke”, Wilkins lecture, December 15, 1949’, PRS, 201A (1950), 439–73 · M. I. Batten, ‘The architecture of Dr Robert Hooke’, Walpole Society, 25 (1936–7), 83–113 · T. Birch, The history of the Royal Society of London, 4 vols. (1756–7), repr. with an introduction by A. R. Hall (1968) · I. B. Cohen, ‘Newton, Hooke and “Boyle's law”. (Discovered by Power and Towneley)’, Nature, 204 (1964), 618–21 · I. B. Cohen, ‘Newton's discovery of gravity’, Scientific American, 244 (1981), 166–79 · M. A. R. Cooper, ‘Robert Hooke's work as surveyor for the City of London in the aftermath of the great fire’, Notes and Records of the Royal Society, 51 (1997), 161–74; 52 (1998), 25–38, 205–20 · M. ’Espinasse, Robert Hooke (1956); repr. (1962) · L. Rostenberg, The library of Robert Hooke (1989) · P. Gouk, ‘The role of acoustics and music theory in the scientific work of Robert Hooke’, Annals of Science, 37 (1980), 573–605 · R. Hooke, diaries, GL, MS 1757 · R. T. Gunther, Early science in Oxford, 6–7: The life and work of Robert Hooke (1930) · R. T. Gunther, Early science in Oxford, 8: The Cutler lectures of Robert Hooke (1931) · R. T. Gunther, Early science in Oxford, 4 (1925), 122, 130; 10 (1935), 114, 195; 12 (1939); 14 (1945) · R. T. Gunther, Early science in Oxford, 13: The life and work of Robert Hooke (1938) · A. R. Hall, ‘Newton on the calculation of central forces’, Annals of Science, 13 (1957), 62–71 · M. Hesse, ‘Hooke's philosophical algebra’, Isis, 57 (1966), 67–83 · M. Hunter and S. Schaffer, eds., Robert Hooke: new studies [London 1988] (1989) · R. Iliffe, ‘Material doubts: Hooke, artisan culture, and the exchange of information in 1670s London’, British Journal for the History of Science, 28 (1995), 285–318 · G. Keynes, A bibliography of Dr. Robert Hooke (1960) · H. Nakajima, ‘Robert Hooke's family and his youth: some new evidence from the will of the Rev. John Hooke’, Notes and Records of the Royal Society, 48 (1994), 11–16 · The correspondence of Isaac Newton, ed. H. W. Turnbull and others, 7 vols. (1959–77) · D. R. Oldroyd, ‘Some writings of Robert Hooke on procedures for the prosecution of scientific enquiry, including his “Lectures of things requisite to a Ntral History”’, Notes and Records of the Royal Society, 41 (1986–7), 145–67 · S. Pumfrey, ‘Ideas above his station: a social study of Hooke's curatorship of experiments’, History of Science, 29 (1991), 1–44 · The diary of Robert Hooke … 1672–1680, ed. H. W. Robinson and W. Adams (1935) · RS, classified papers, vol. 20 · RS, early letters, H.3.64 · The posthumous works of Robert Hooke, ed. R. Waller (1705), repr. with introduction by R. S. Westfall, 1969 · J. Ward, The lives of the professors of Gresham College (1740) · R. S. Westfall, ‘Hooke and the law of gravitation’, British Journal for the History of Science, 3 (1966–7), 245–61 · M. Hunter, ‘Science, technology and patronage: Robert Hooke and the Cutlerian lectureship’, Establishing the new science: the experience of the early Royal Society (1989), 297–338 · P. J. Pugliese, ‘The scientific achievement of Robert Hooke’, PhD diss., Harvard U., 1982

Archives  

BL, papers and corresp., incl. essay on the inflection of a direct motion into a curve, 1666, discourse concerning Newton's theory of light, account of Burnet's ‘Archaeologiae philosophicae’, method for making a history of the weather, and drawings, Sloane MSS 698, 917, 1039, 1676–1677, 1942, 3823, 4062, 4067, Add. MSS 5238, 6193–6209 · GL, papers, incl. diary, travel journals, reports as surveyor for rebuilding London after the great fire, anatomical observations, lectures, and therapeutical notes · RS, corresp. and papers · Trinity Cam., papers, incl. ‘Philosophicall scribbles’, and some corresp.


Wealth at death  

‘many thousands of pounds’: Posthumous works, ed. Waller, xiii