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".[1] 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.[2][3] 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.[4] 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.[5] 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". In 1653, Hooke (who had also undertaken a course of twenty lessons on the organ) secured a chorister's place at Christ Church, Oxford.[6] He was employed as a "chemical assistant" to Dr Thomas Willis, for whom Hooke developed a great admiration. 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 "machina Boyleana" or air pump.[7] 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 Wilkins, but concluded that human muscles were insufficient to the task. 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."[8] 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."[9] Derham also attributes it to Hooke.[10]