Robert Hooke

Robert Hooke, FRS (18 July 1635 – 3 March 1703) was an English natural philosopher and polymath who played an important role in the scientific revolution, through both experimental and theoretical work.

Hooke is known principally for his law of elasticity (Hooke's Law). He is also remembered for his work as "the father of microscopy" &mdash; it was Hooke who coined the term "cell" to describe the basic unit of life &mdash; but he also assisted Robert Boyle and built the vacuum pumps used in Boyle's gas law experiments, was an important architect of his time, was chief surveyor to the City of London after the Great Fire, built some of the earliest Gregorian telescopes, observed the rotations of Mars and Jupiter, and was an early proponent of the theory of evolution through his observations of microscopic fossils. 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 also deduced from experiments 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 work was conducted in his capacity as curator of experiments of the Royal Society, a post he held from 1662.

Hooke was, by all accounts, a remarkably industrious man, and was at one time simultaneously the curator of the Royal Society and a member of its council, Gresham Professor of Geometry and Chief Surveyor to the City of London.

Hooke's reputation was largely forgotten during the eighteenth century, and this is popularly attributed to a dispute with Isaac Newton over credit for his work on gravitation; 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. 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 recognised as one of the most important scientists of his age.

Biography


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.

Early life
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 sons and two daughters, and seven years separated him from the next youngest. Their father served in the Church of England, specifically as the curate of Freshwater's Church of All Saints; his three brothers also were 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 poor health. He was a Royalist and almost certainly one 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.

On his father's death in 1648, Robert was left a sum of one hundred pounds with which to buy an apprenticeship; with his poor health 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.

Oxford, Boyle
In 1653, Hooke (who had also undertaken a course of twenty lessons on the organ) secured a chorister's place at Christ Church, Oxford. There he met the natural philosopher Robert Boyle, and gained employment as his assistant from about 1655 to 1662, constructing, operating, and demonstrating Boyle's air pump. He did not take his Master of Arts until 1662 or 1663. In 1659 Hooke described some elements of a method of heavier-than-air flight to the Warden of Wadham College, but concluded that human muscles were insufficient to the task.

Hooke began to be noticed around 1655, at which time there was a gathering in Oxford of men devoted to the study and demonstration of various elements of natural philosophy. These individuals held "philosophical meetings", of which 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 these experiments based on the pump of Gratorix, 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.

Watch escapement
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 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 sufficient 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. Hook, formerly professor of geometry in Gresham College at London, was the inventor." Derham also attributes it to Hooke.

Royal Society
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 Robery 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 of his own devising 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 while full of 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 200ft 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.

Personality and disputes
Much has been written of the unpleasant side of Hooke's personality, starting with comments by his first biographer, Richard Waller, that Hooke was "in person, but despicable" and "melancholy, mistrustful, and jealous." Waller's comments influenced other writers for well over two centuries, so that a picture of Hooke as a disgruntled selfish, anti-social curmudgeon dominates many older books and articles. For example, Arthur Berry said that Hooke "claimed credit for most of the scientific discoveries of the time." Sullivan wrote that Hooke was "positively unscrupulous" and possessing an "uneasy apprehensive vanity" in dealings with Newton Manuel used the phrase "cantankerous, envious, vengeful" in his description. More described Hooke having both a "cynical temperament" and a "caustic tongue." Andrade was more sympathetic, but still used the adjectives "difficult", "suspicious", and "irritable" in describing Hooke.

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. He was granted a large number of patents for inventions and refinements in the fields of elasticity, optics and barometry.

Mechanics
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. It is interesting from a twentieth-century vantage point that Hooke first announced his law of elasticity as an anagram. This was a method sometimes used by scientists, such as Hooke, Huygens, Galileo, and others, to establish priority for a discovery without revealing details.



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.

Microscopy
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".



Astronomy
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.

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.

Hooke the architect




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 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.

Likenesses
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 Time's 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 and by the German researcher Andreas Pechtl of Johannes Gutenberg University of Mainz. The portrait identified by Jardine, in fact, depicts the Flemish scholar Jan Baptist van Helmont.

Other possible likenesses of Hooke include the following:


 * A seal used by Hooke displays an unusual profile portrait of a man's head, which some have argued portrays Hooke.


 * The engraved frontispiece to the 1728 edition of Chambers' Cyclopedia shows a drawing of a bust of Robert Hooke. The extent to which the drawing is based on an actual work of art is unknown.


 * A memorial window existed at St Helen's Bishopsgate in London, but it was a formulaic rendering, not a likeness. The window was destroyed in the 1993 Bishopsgate bombing.

Commemorations

 * Craters on the Moon and on Mars are named in his honour.
 * 3514 Hooke, an asteroid (1971 UJ)
 * The Hooke Medal