罗伯特·胡克Robert Hooke

罗伯特·胡克 的父亲是 John Hooke，他是怀特岛 Freshwater 诸圣教堂的助理牧师。虽然正式上是助理牧师，但由于牧师也是格洛斯特大教堂和韦尔斯大教堂的主任牧师，John Hooke 被留下负责诸圣教堂。这是一座富裕的教堂，因为它在剑桥大学圣 弗瑞兹·约翰 学院的赞助下。除了在教堂的职责外，John Hooke 还经营着一所附属于教堂的小学校，并担任私人教师。胡克 有一个名叫 约翰 的兄弟，与他父亲同名，比他大五岁。

关于胡克童年的细节所知甚少。我们在此记录的是他晚年向朋友提及的信息。胡克像他那个时代的许多孩子一样，体弱多病，被认为活不到成年。他的父亲来自一个所有男孩都期望加入教会的家庭（John Hooke的三个兄弟都是牧师），因此如果胡克小时候身体健康，毫无疑问他会遵循家族传统。事实上，胡克的父母确实开始本着这一想法为他安排教育，但他不断遭受头痛之苦，使学习变得困难。由于缺乏他会活到成年的信心，胡克的父母放弃了他的教育，让他自行其是。

胡克自己的想法涉及他的观察能力和机械技能。他观察周围的植物、动物、农场、岩石、悬崖、大海和海滩。他对机械玩具和钟表着迷，用木头制作了许多东西，从一座能走的钟到一艘装备齐全、带有可操作火炮的船模型。Waller在1705年出版的胡克的Posthumous Works序言中，将他对于机械学的信念，特别是他相信自然是一台复杂机器的信念，追溯到他大约十岁时让想象力和才能尽情驰骋的时期。

大约从胡克十岁起，他的父亲生病了，这促使胡克以他感兴趣的极为实用的方式自学。胡克不仅在科学上显示出才能，在绘画上也显示出技能。当时有一位肖像画家约翰 Hoskyns在淡水工作，胡克常常看他作画。很快他就模仿Hoskyns使用钢笔和粉笔的方式，并临摹Hoskyns的肖像画。他的才能显而易见，1648年父亲去世后，胡克的家人认定绘画是他谋生的最佳途径。父亲留给他40英镑以及父亲所有的书籍（常被引用的100英镑这个数字是一个被多次重复的错误），家人送他去伦敦，成为肖像画家Peter Lely的学徒。

Lely曾在荷兰哈勒姆学习，在胡克被送到他那里大约五年前就在伦敦立足。Lely很快因绘制查理一世和约克公爵詹姆斯的肖像画而声名鹊起。受Van Dyck影响，他成为英格兰技术上最精湛的画家，胡克本可以从这样一位顶尖专家那里学到很多。然而，他很快认定在Lely门下学习是浪费钱，并决定自己真正需要的是学校教育。胡克进入威斯敏斯特学校，寄宿在校长Richard Busby家中。胡克确实很幸运能受到Busby的影响，Busby是一位杰出的教师，很快意识到自己有一个非常出色的学生。胡克在入学第一周结束时就已经掌握了欧几里得的Elements的前六卷，但Busby似乎明白正规学习对胡克并非最佳，于是鼓励他在自己的图书馆里自学[10]：-

胡克很幸运地赢得了Busby博士的尊重，并像上威斯敏斯特学校之前一样，被允许追求自己的知识兴趣。

胡克学习了拉丁语和希腊语，不过，尽管他喜欢说拉丁语，但与同时代人不同，他从未用拉丁语写作。他迅速获得的几何学知识很快被应用到他真正热爱的力学上，他开始发明可能的飞行机器。音乐是他的另一项兴趣，他学会了弹管风琴。1653年，他觉得自己已经吸收了威斯敏斯特学校所能提供的全部知识，于是进入牛津大学基督堂学院，并在那里获得了一个唱诗班席位。他开始在牛津学习，这对Thomas Willis来说是一个特别重要的时期，Seth Ward、罗伯特·波义耳、约翰·维尔金斯、约翰·沃利斯、克里斯托弗·雷恩和William Petty都属于那些定期聚会的人，他们组成了“无形学院”或“哲学学院”的“牛津分支”，该学院于1648-49年成立，当时一些在伦敦聚会的科学家迁到了牛津。

胡克从Seth Ward那里学习天文学，并以他的力学知识给约翰·维尔金斯留下深刻印象。约翰·维尔金斯送给他一本自己的书Mathematical Magick, or the wonders that may be performed by mechanical geometry，这本书是在胡克到达牛津五年前出版的。这本书鼓励胡克继续尝试发明飞行机器，他在沃德姆学院场地上用滑轮做实验。有一段时间，胡克协助Willis进行解剖实验。他参与了当时英国顶尖科学家的工作，通过获得广泛学科的技能而受益匪浅[1]：-

……胡克从未获得学士学位[但]牛津给予他的，是一千个学位也无法比拟的。

罗伯特·波义耳正在寻找一位助手，Willis向他推荐了胡克。从1655年起，他受雇于罗伯特·波义耳，他的第一个项目是制造一台空气泵。罗伯特·波义耳的主要兴趣领域是化学，但他读到过von Guericke借助空气泵所做的实验，并且知道胡克在机械仪器方面的技能，便问他能否制造一台。Greatorix制造过一台比von Guericke所用的更好的空气泵，但胡克觉得自己能够改进这一设计。他确实做到了，胡克设计并制造出了本质上就是现代空气泵的装置。

胡克从来不是一个一次只做一件事的人，事实上，当他的头脑从一个想法跳到另一个想法时，他似乎处于最佳状态。在研制空气泵的同时，他也在思考钟表以及如何用它们来确定海上经度。意识到摆钟在颠簸摇晃的船上计时的弱点后，他思考了：-

……使用弹簧而非重力来使物体在任何姿态下振动。

他认为，与其让摆轮由摆锤控制、而摆锤又通过重力起作用，不如用弹簧控制摆轮，这对于人们可能随身携带的便携式计时器，或者必须在船上持续保持正确时间的计时器，会有巨大优势。他大约在1658年开始实验，到1660年已取得两项重大进展，即使用由螺旋弹簧控制的摆轮，以及一种称为锚形擒纵机构的改进型擒纵机构。1660年，他在为钟表摆轮弹簧进行设计时，发现了胡克定律的一个实例。然而，他直到1678年所作的讲座Of Spring中才宣布了弹性的一般定律。

事实上，1660年发生了一件关于胡克的弹簧控制钟表的相当奇怪的事件。那一年，他在设计弹簧控制钟表时得到了克里斯托弗·雷恩、Moray和威廉·布朗克的支持，并起草了一项专利。这本来可能让他发一笔财，但当他意识到这项专利将允许任何改进他设计的人获得版税时，他拒绝继续申请专利。

政治环境此时决定了事件的进程。1658年克伦威尔去世后，他的儿子接任但无能。牛津的许多科学家因其清教徒同情心而被任命，现在他们失去了职位并搬到了伦敦。被任命为苏格兰总督的蒙克率军进军伦敦，并于1660年初恢复了秩序。蒙克呼吁议会进行新的选举，他知道人民的情绪会选出保皇党人。伦敦局势的改善，特别是驻扎在格雷沙姆学院的军队现在离开了，使得科学家们能够再次在学院开会。1660年11月28日星期三，在格雷沙姆学院的一次会议构成了促进物理-数学实验学习学会，他们宣布该学会将促进实验哲学。

胡克的第一份出版物是一本关于毛细作用的小册子。1661年4月10日，他的论文在学会上宣读，其中他表明管子越窄，水在其中上升得越高。此时，格雷沙姆的学会已向国王查理二世请愿，要求承认它并授予皇家特许状。1662年7月15日由国玺通过的皇家特许状创建了伦敦皇家学会，皇家特许状包含一项任命实验管理员的条款。Society已经有意任命胡克担任此职位，事实上在1662年11月5日他被授予该职位。在许多方面，这看起来并不是一笔好交易，因为他被要求在学会的每次会议上演示三到四个实验，这相当不现实，而且除了胡克之外，怀疑是否有人能设想能够提供。尽管希望学会最终能够向胡克提供报酬，但他被要求在没有报酬的情况下承担这项工作，直到学会有能力支付为止。

事实上，胡克对强加给他的不可能任务的反应是在接下来的15年里产生了大量原创想法。可以说，正是通过胡克的大量想法，Society才繁荣起来，但同样，这些要求也充分激发了胡克的天才。尽管这些要求意味着他从未有时间像人们期望一位顶尖科学家那样逐步发展自己的想法，但另一方面，让他的思维从一个半成型的想法跳到下一个似乎适合他的天性。他于1663年6月3日被选入皇家学会，尽管他仍然没有收到报酬，但至少学会准备允许他成为会士而无需支付年费。

1664年，Society同意支付胡克每年80英镑的薪水，但此后不久，他们为他安排了机械艺术卡特勒讲座职位，年薪50英镑，然后将他的实验管理员薪水降至30英镑，但给了他终身任命。这并没有提供胡克可能希望的经济保障，因为学会经常没有足够的资金支付他作为实验管理员的报酬，而当他作为机械艺术卡特勒讲座的职责未获报酬时，他被迫上法庭才能获得付款。

不过，他确实获得了另一个职位，即伦敦格雷沙姆学院的几何学教授，于1665年受聘。该职位为他提供了学院内的住所，并要求他在学期内每周讲授一次课。讲课必须用拉丁语进行，随后再用英语重复一遍。他被要求必须未婚，但允许有一名管家。

1665年是胡克首次获得世界性科学声誉的一年。他当年出版的著作Micrographia，包含了胡克用自己制造的显微镜研究过的物体的精美图片。这本书还包含若干基础性的生物学发现。Pepys在日记中写道：-

上床之前，我在房间里一直坐到两点钟，读胡克先生的《显微观察》，这是我一生中读过的最精巧的书。

Westfall写道[1]：-

《显微图谱》仍然是十七世纪科学的杰作之一。……[它]不是对任何一个问题的系统研究，而是一束来自矿物、动物和植物界的观察。最重要的是，这本书展示了显微镜能为生物科学做些什么。

胡克发明了锥摆，并且是第一个建造格雷果里反射望远镜的人。他做出了重要的天文观测，包括木星绕其轴旋转这一事实，这是他从观察斑点中发现的。随后他发明了太阳观测仪，试图利用太阳黑子测量太阳的自转。他绘制了火星的图画，这些图画后来被用来确定其自转周期。他观测了几颗彗星，并就它们提出了若干重要问题，包括为什么彗尾背离太阳，以及如果彗星在燃烧，它如何能燃烧如此之久，并在没有空气的地方燃烧。1666年，他提出可以用摆来测量重力。

除了担任格雷沙姆学院几何学教授之外，胡克还担任城市测量员一职。他是一位非常称职的建筑师，并且在1666年大火后重建伦敦的项目中，是克里斯托弗·雷恩的首席助手。Westfall写道[1]：-

雷恩和胡克主导并指导了这项工作，并巩固了持续他们一生的友谊。对胡克来说，测量员的职位是一笔经济上的意外之财，足以弥补他其他收入的不确定性。

当艾萨克·牛顿在1672年提出他的光和颜色理论时，胡克声称艾萨克·牛顿理论中正确的部分是从他自己1665年关于光的想法中窃取的，而原创的部分则是错误的。这标志着两人之间激烈争论的开始。1672年，胡克试图证明地球绕太阳沿椭圆运动，六年后提出引力平方反比定律来解释行星运动。胡克在1679年写信给艾萨克·牛顿征求他的意见：-

……通过切线（惯性运动）和朝向中心物体的吸引运动来复合行星的直线运动……我的假设是，吸引力总是与到中心的距离的平方成反比……

然而，胡克似乎无法对他的猜想给出数学证明，或者也许不愿将时间投入这类追求。不过他声称对平方反比定律拥有优先权，这导致他与艾萨克·牛顿发生了激烈争执，结果后者从Principia中删除了所有提及胡克的内容。

在胡克的一生中，与同行科学家的频繁激烈争执时有发生。另一方面，我们应当注意到，他与一些同事关系非常好，尤其是罗伯特·波义耳和克里斯托弗·雷恩。历史学家将胡克描述为一个难以相处且不讲理的人，但在许多方面这是一种苛刻的评判。毫无疑问，胡克真心感到别人窃取了他最先提出的想法。很容易看出为什么会发生这种情况。胡克确实提出了大量卓越的想法，其中许多被他人声称拥有，不是因为他们想从他那里窃取，而是因为胡克从未将自己的想法进一步发展成全面的理论。他未能从自己受启发的想法中发展出重大理论，原因很简单：他并不真正具备像他的一些同时代人如艾萨克·牛顿和克里斯蒂安·惠更斯那样发展出如此全面理论的技术能力。

胡克的日记是引人入胜的文献，因为它们不仅让我们了解他的性格，还生动地描绘了他那个时代。以下是一些取自[10]的例子：-

他走路轻快，喜欢在城北的田野里散步。……他通常早起，也许是为了节省蜡烛，并在日光下工作，以免眼睛疲劳。……有时胡克会通宵工作，然后在晚餐后小睡一会儿。除了饮用各种水……他还喝白兰地、波特酒、红葡萄酒、雪利酒和桦树汁酒，他觉得后者很美味。他还有一桶Flanstead's ale和Tillotson's ale。有几次他记录自己喝醉了……他是个合群的人，喜欢与人交往，尤其是那些去过国外旅行的人……

胡克年岁渐长，变得更加愤世嫉俗，会闭门谢客。他生命最后几年写的文章充满了尖刻的评论。1690年2月，胡克向皇家学会做了两次演讲，部分内容转载于[26]。根据Waller [11]，此时胡克是：-

……经常受到头痛、头晕和昏厥的困扰，并且全身普遍衰退，这妨碍了他的哲学研究，但他仍然在力所能及时读一些演讲。

胡克在这些讲座中显示出他内心多么痛苦。例如，在第二次讲座中他说：-

[克里斯蒂安·惠更斯的序言]涉及的是我本人首先发现并向这个学会展示的、以及多年来（晚近艾萨克·牛顿先生承蒙好意将其印刷出版并作为他自己的发明）的那些重力性质。尤其是地球呈椭圆形状这一点，大约27年前，我因将摆钟运往海上之机向这个学会宣读，此后又两次宣读，尽管我运气不佳未获听取，但我设想在座有些人很可能还记得并知道，艾萨克·牛顿先生是在我在此处宣读并展示其实验和论证、并回复了来自牛津的约翰·沃利斯博士那封责备信之后数周，才把那项补充内容寄去付印的。然而我很高兴地发现，当人们放下先入之见和偏见时，真理终将获胜。既然这一点已在世上获得赞同者，而且也是那些有思想的人，那么我毫不怀疑，我在此首次做出的其他多项发现（当它们得到充分考虑和检验时）将不会像有些人乐意使之显得的那样不合理或荒谬。

他去世后，Waller编辑了[11]，这是一部主要收录胡克此前未发表作品的重要出版物。这部作品的很大一部分专门收录胡克关于地震的讲座。在三十年间，他对地质学做出了重大贡献，尤其是他对化石遗存的研究，这使他确信地球表面发生过重大变化，将海洋动物的化石贝壳抬升到了山脉的高处。

胡克被描述为一个：-

……瘦削、驼背且丑陋的人……

因此人们认为他没有坐下来让人画过肖像。最近在皇家学会发现的一幅可能肖像，现已被确认画的是另一个人。

Robert Hooke's father was John Hooke who was a curate at All Saints Church in Freshwater on the Isle of Wight. Although formally a curate, since the minister was also Dean of Gloucester Cathedral and of Wells, John Hooke was left in charge of All Saints. It was a well off church being in the patronage of St John's College, Cambridge. As well as his duties in the church, John Hooke also ran a small school attached to the church and acted as a private tutor. Robert had a brother named John, the same name as his father, who was five years older.

Relatively few details of Robert's childhood are known. What we record here is information which he mentioned to his friends later in his life. Robert, like many children of his day, had poor health and was not expected to reach adulthood. His father was from a family in which it was expected that all the boys joined the Church (John Hooke's three brothers were all ministers) so had Robert enjoyed good health as a child there is no doubt that he would have followed the family tradition. As it was Robert's parents did begin to set up his education with this in mind but he continually suffered from headaches which made studying hard. Lacking confidence that he would reach adulthood, Robert's parents gave up on his education, leaving him much to his own devices.

Robert's own ideas involved his observational skills and his mechanical skills. He observed the plants, the animals, the farms, the rocks, the cliffs, the sea, and the beaches around him. He was fascinated by mechanical toys and clocks, making many things from wood from a working clock to a model of a fully rigged ship with working guns. Waller, in the Preface to Hooke's Posthumous Works published in 1705, dates his belief in mechanics, in particular his belief that nature was a complicated machine, from the time that he let his imagination and his talents run riot at about age ten.

From about the time Robert was ten his father became ill and this contributed to Robert being left to educate himself in the highly practical way that interested him. Not only did Robert show talents at science, but he also showed skills at drawing. There was a portrait painter, John Hoskyns, who was working at Freshwater at this time and Robert used to watch him at work. Soon he was imitating the way that Hoskyns used pen and chalk, and he was making copies of Hoskyns' portraits. His talent was clear and after the death of his father in 1648 Robert's family decided that drawing was the best way that he might earn a living. He was left £40 by his father, together with all his father's books (the often quoted figure of £100 is a much repeated error), and his family sent him to London to become an apprentice to the Peter Lely, a portrait painter.

Lely had studied at Haarlem in Holland and set himself up in London about five years before Hooke was sent to him. Lely quickly gained fame painting portraits of Charles I and James, Duke of York. Influenced by Van Dyck he became the most technically proficient painter in England and Hooke could have learnt much from such a leading expert. However, he soon decided that it would waste his money studying under Lely, and he made the decision that what he really needed was a school education. Hooke enrolled in Westminster School, boarding in the house of the headmaster Richard Busby. Indeed Hooke was fortunate to come under the influence of Busby who was an outstanding teacher who quickly realised that he had a quite remarkable pupil. Hooke had mastered the first six books of Euclid's Elements by the end of his first week at school but Busby seemed to understand that formal learning was not going to be best for Hooke and so encouraged him to study by himself in his library [10]:-

Hooke was fortunate in gaining the respect of Dr Busby and being left to follow his own pursuits of knowledge just as he had before attending Westminster School.

At Westminster Hooke learnt Latin and Greek but, although he enjoyed speaking Latin, unlike his contemporaries he never wrote in Latin. His rapidly gained understanding of geometry was soon applied to his real love of mechanics and he began to invent possible flying machines. Music was another of his interests and he learnt to play the organ. In 1653, feeling that he had assimilated as much knowledge as Westminster School could offer, he entered Christ Church, Oxford where he won a chorister's place. He began to study at Oxford at a particularly significant time for Thomas Willis, Seth Ward, Robert Boyle, John Wilkins, John Wallis, Christopher Wren and William Petty were among those who regularly met as the "Oxford branch" of the "invisible college" or the "philosophical college" which had been set up in 1648-49 when some of the scientists meeting in London moved to Oxford.

In Oxford Hooke learnt astronomy from Seth Ward and impressed Wilkins with his knowledge of mechanics. Wilkins gave him a copy of his book Mathematical Magick, or the wonders that may be performed by mechanical geometry which he had published five years before Hooke arrived in Oxford. This book encouraged Hooke to continue to try to invent a flying machine and he conducted experiments in the grounds of Wadham College with pulleys. For a while Hooke assisted Willis with his dissection experiments. He was involved with the top English scientists of the day, benefiting greatly by acquiring skills in a wide range of disciplines [1]:-

... Hooke never took a bachelor's degree [but] Oxford had given him more than a thousand degrees could match.

Boyle was looking for an assistant and Willis recommended Hooke to him. From 1655 he was employed by Boyle and his first project was to construct an air pump. The main area of Boyle's interests were in chemistry but he had read of experiments conducted by von Guericke with the aid of an air pump and, knowing Hooke's skill with mechanical instruments, asked him if he could build one. A better air pump than that used by von Guericke had been made by Greatorix but Hooke felt that he could improve on the design. Indeed he did so and Hooke designed and built what is essentially the modern air pump.

Hooke was never a person who did one thing at a time, indeed he seemed at his best when his mind was jumping from one idea to another. At the same time that he was working on the air pump he was also thinking about clocks and how they could be used in determining the longitude at sea. Realising the weakness of the pendulum clock in keeping time on a ship which was pitching and tossing, he wondered about the:-

... use of springs instead of gravity for making a body vibrate in any posture.

Rather than the balance wheel being controlled by a pendulum which in turn operated through gravity, he reasoned that controlling the balance wheel with a spring would have huge advantages for a portable timekeeper that one might carry around or one which would have to continue to keep the correct time on a ship. Beginning his experiments around 1658 he had made two significant steps by 1660, namely the use of a balance controlled by a spiral spring and an improved escapement called the anchor escapement. In 1660 he discovered an instance of Hooke's law while working on designs for the balance springs of clocks. However he only announced the general law of elasticity in his lecture Of Spring given in 1678.

In fact 1660 was the year when a rather strange event happened regarding Hooke's spring controlled clocks. In that year he was backed by Wren, Moray and Brouncker in his design of a spring controlled clock and a patent was drawn up. It could have led to him making a fortune, but when he realised that the patent would allow anyone who improved on his design to receive the royalties, he refused to continue with the patent.

Political circumstances now determined the course of events. After Cromwell's death in 1658 his son took over but was ineffectual. Many of the scientists in Oxford had been appointed because of their Puritan sympathies and they now lost their positions and moved to London. Monck, who had been appointed as governor in Scotland, marched an army on London and restored order in early 1660. Monck called for new elections to Parliament, knowing that the mood of the people would elect Royalists. The improvement in the situation in London, in particular troops which had been stationed in Gresham College now left, allowed the scientists to begin meeting again in the College. On Wednesday 28 November 1660 a meeting in Gresham College constituted the Society for the Promoting of Physico-Mathematical Experimental Learning which they declared would promote experimental philosophy.

Hooke's first publication was a pamphlet on capillary action. On 10 April 1661 his paper was read to the Society in which he showed that the narrower the tube, the higher water rose in it. The Society at Gresham had by this time petitioned King Charles II to recognise it and to make a royal grant of incorporation. The Royal Charter, which was passed by the Great Seal on 15 July 1662, created the Royal Society of London and the Royal Charter contained a provision to appoint a Curator of Experiments. The Society already had in mind appointing Hooke to this position and indeed on 5 November 1662 he was given the position. In many ways it did not look a marvellous deal for he was required to demonstrate three or four experiments at every meeting of the Society, something that was quite unrealistic and it is doubtful that anyone other than Hooke could have contemplated being able to provide. Although it was hoped that the Society would eventually be able to provide payment to Hooke, he was required to undertake the work without any recompense until the Society was in a position to do so.

In fact Hooke reacted to the impossible task set him by producing a wealth of original ideas over the following 15 years. It would be fair to say that it was through Hooke's flood of ideas that the Society prospered, but equally the demands brought out Hooke's genius to the full. Although the demands meant that he never had time to develop his ideas over time as one would expect a leading scientist to do, on the other hand it seemed to suit his nature to have his mind jump for one half thought out idea to the next. He was elected to the Royal Society on 3 June 1663 and, although he was still receiving no payment, at least the Society was prepared to allow him to become a Fellow without paying the annual fees.

In 1664 the Society agreed to pay Hooke a salary of £80 per year but shortly after this they arranged the position of Cutlerian Lecturer in the Mechanical Arts for him at a salary of £50 per year and then reduced his salary as Curator of Experiments to £30 but gave him an appointment for life. This did not provide the financial security that Hooke might have hoped for, since the Society often did not have sufficient funds to pay him as Curator of Experiments and when he was not paid for his duties as Cutlerian Lecturer in the Mechanical Arts he was forced to go to court to get payment.

He did however secure another appointment, namely that of Professor of Geometry at Gresham College, London, being appointed there in 1665. The position gave him rooms at the College and required him to give one lecture each week in term time. The lecture had to be given in Latin and subsequently repeated in English. He was required to be unmarried but was permitted a housekeeper.

The year 1665 was the one when Hooke first achieved worldwide scientific fame. His book Micrographia, published that year, contained beautiful pictures of objects Hooke had studied through a microscope he had made himself. The book also contains a number of fundamental biological discoveries. Pepys wrote in his diary:-

Before I went to bed I sat up till two o'clock in my chamber reading Mr Hooke's Microscopical Observations, the most ingenious book that ever I read in my life.

Westfall writes [1]:-

Micrographia remains one of the masterpieces of seventeenth century science. ... [it] presented not a systematic investigation of any one question, but a bouquet of observations with courses from the mineral, animal and vegetable kingdoms. Above all, the book suggested what the microscope could do for biological science.

Hooke invented the conical pendulum and was the first person to build a Gregorian reflecting telescope. He made important astronomical observations including the fact that Jupiter revolves on its axis which he discovered from observing spots. He then invented a helioscope to attempt to measure the rotation of the sun using sunspots. He made drawings of Mars which were later used to determine its period of rotation. He observed several comets and asked a number of important questions about them, including why the tail points away from the sun, and how if the comet is burning it could burn for so long and burn in a place where there is no air. In 1666 he proposed that gravity could be measured using a pendulum.

In addition to his post as Professor of Geometry at Gresham College, Hooke held the post of City Surveyor. He was a very competent architect and was chief assistant to Wren in his project to rebuild London after the Great Fire of 1666. Westfall writes [1]:-

Wren and Hooke dominated and guided the work, and cemented a friendship that lasted throughout their lives. To Hooke the position of surveyor was a financial boon, more than compensating for the uncertainty of his other income.

When Newton produced his theory of light and colour in 1672, Hooke claimed that what was correct in Newton's theory was stolen from his own ideas about light of 1665 and what was original was wrong. This marked the beginning of severe arguments between the two. In 1672 Hooke attempted to prove that the Earth moves in an ellipse round the Sun and six years later proposed that inverse square law of gravitation to explain planetary motions. Hooke wrote to Newton in 1679 asking for his opinion:-

... of compounding the celestiall motions of the planetts of a direct motion by the tangent (inertial motion) and an attractive motion towards the centrall body ... my supposition is that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall ...

Hooke, however, seemed unable to give a mathematical proof of his conjectures or perhaps unwilling to devote his time to this type of pursuit. However he claimed priority over the inverse square law and this led to a bitter dispute with Newton who, as a consequence, removed all references to Hooke from the Principia.

Frequent bitter disputes with fellow scientists occurred throughout Hooke's life. On the other hand, we should note that he was on very good terms with some colleagues, particularly Boyle and Wren. Historians have described Hooke as a difficult and unreasonable man but in many ways this is a harsh judgement. There is no doubt that Hooke genuinely felt that others had stolen ideas which he had been first to put forward. It is easy to see why this happened. Hooke did indeed come up with a vast range of brilliant ideas many of which were claimed by others not because they wished to steal them from him, but rather because Hooke never followed through developing his ideas into building comprehensive theories. He failed to develop major theories from his inspired ideas for the simple reason that he did not really have the technical ability to develop such comprehensive theories as some of his contemporaries like Newton and Huygens.

The diaries of Hooke are fascinating documents in that they tell us something about his character as well as painting an interesting picture of his times. Here are some examples taken from [10]:-

He was a brisk walker, and enjoyed walking in the fields north of the City. ... he generally rose early, perhaps to save candles, and to work in daylight and prevent strain to his eyes. ... Sometimes Hooke would work all through the night, and then have a nap after dinner. As well as drinking a variety of waters ... he drank brandy, port, claret, sack, and birch juice wine which he found to be delicious. He also had a barrel of Flanstead's ale and Tillotson's ale. There are a few instances when he recorded that he had been drunk ... He was a gregarious person, who liked to meet people, particularly those who had travelled abroad ...

As Hooke grew older he became more cynical and would shut himself away from company. The papers which he wrote in the last few years of his life are filled with bitter comments. In February 1690 Hooke gave two lectures to the Royal Society which are reproduced in part in [26]. At this time, according to Waller [11], Hooke was:-

.. often troubled with headaches, giddiness, and fainting, and with a general decay all over, which hindered his philosophical studies, yet he still read some lectures whenever he was able.

Hooke shows how bitter he feels in these lectures. For example, in the second lecture he said:-

[Huygens' Preface] is concerning those properties of gravity which I myself first discovered and showed to this Society and years since, which of late Mr Newton has done me the favour to print and publish as his own inventions. And particularly that of the oval figure of the Earth which was read by me to this Society about 27 years since upon the occasion of the carrying the pendulum clocks to sea and at two other times since, though I have had the ill fortune not to be heard, and I conceive there are some present that may very well remember and do know that Mr Newton did not send up that addition to his book till some weeks after I had read and showed the experiments and demonstration thereof in this place and had answered the reproachful letter of Dr Wallis from Oxford. However I am well pleased to find that the truth will at length prevail when men have laid aside their prepossessions and prejudices. And as that hath found approvers in the world and those thinking men too, so I doubt not but that divers other discoveries which I have here first made (when they come to be well considered and examined) be found not so unreasonable or extravagant as some would willingly make them.

After his death Waller edited [11], a major publication of previously unpublished works by Hooke. A large portion of this work is devoted to Hooke's lectures on earthquakes. Over a period of thirty years he made major contributions to geology, particularly his investigation of fossil remains which convinced him that major changes had occurred in the Earth's surface which had lifted fossilised shells of marine animals to high points in mountain ranges.

Hooke has been described as a:-

... lean, bent and ugly man ...

and so it was believed that he did not sit for a portrait. A possible portrait recently found at the Royal Society has now been established as being of someone else.