开尔文William Thomson, 1st Baron Kelvin

William Thomson的父亲詹姆斯·汤姆森原本打算成为长老会教堂的牧师，但后来选择了数学家的学术生涯。开尔文的母亲在他六岁时去世，从那时起由父亲抚养长大。开尔文出生时，詹姆斯·汤姆森是贝尔法斯特的工程学教授，当开尔文八岁时，他的父亲詹姆斯·汤姆森被任命为格拉斯哥大学的数学讲席。詹姆斯·汤姆森是一位专制的父亲，以严格的长老会方式抚养家人。开尔文的姐姐这样描述这段童年[5]：-

我们的父亲每周日早上定期给我们读《旧约》中的一些章节，晚上读《新约》中的一些章节。

然而，尽管父亲非常严格，他与开尔文的关系却非常亲密。开尔文从父亲那里学习数学，并在很小的时候就成为一名有造诣的数学家，了解该学科的最新发展。

开尔文从10岁起就读于格拉斯哥大学。这个年龄并不像人们想象的那么不寻常，因为当时苏格兰的大学在某种程度上与学校竞争最聪明的低龄学生。汤姆孙于1838年14岁时开始了我们会认为是大学水平的工作。在1838-39学年，他学习了天文学和化学。第二年，他修读了自然哲学课程（今天称为物理学），其中包括对热、电和磁的研究。他15岁时，他的Essay on the Figure of the Earth为他赢得了格拉斯哥大学的金质奖章，这是一部真正卓越的著作，包含重要的思想，汤姆孙一生中反复回到这些思想。

在1839-40学年结束时，汤姆逊阅读了约瑟夫·傅里叶的The Analytical Theory of Heat，这是一部关于抽象数学应用于热流的工作。他后来写道[10]：-

我从大学图书馆借出了约瑟夫·傅里叶；两周内我就掌握了它——通读了一遍。

事实上，当时格拉斯哥的讲师们对法国数学处理物理科学的方法有着浓厚的兴趣。特别是约瑟夫·拉格朗日、皮埃尔·西蒙·拉普拉斯、阿德里安-马里·勒让德、奥古斯丁·菲涅耳和约瑟夫·傅里叶的著作受到了“崇敬”的对待，用汤姆逊后来用来描述他的讲师们对这些法国数学家的态度的词来说。事实上，汤姆逊在1839-40学年还阅读了皮埃尔·西蒙·拉普拉斯的Mécanique céleste，并在此期间访问了巴黎。威尔逊在[11]中这样描述汤姆逊在格拉斯哥的本科岁月：-

……从1838年到1841年，开尔文似乎已经彻底熟悉了热、电和磁的现象。Meikleham[自然哲学教授]显然鼓励对自然哲学的这些分支采取某种统一的观点。他的教授们不仅让他接触到许多现代实验和数学研究，而且还阐明了将物理理论数学化的理想，尽管他们中没有一个人本人精通这门技艺。

1841年，汤姆孙进入剑桥，同年他的第一篇论文发表。这篇论文Fourier's expansions of functions in trigonometrical series是为了捍卫约瑟夫·傅里叶的数学，反驳爱丁堡大学数学教授的批评。一篇更重要的论文On the uniform motion of heat and its connection with the mathematical theory of electricity于1842年发表，当时汤姆孙正在剑桥准备数学荣誉学位考试。

在剑桥，汤姆孙由威廉·霍普金斯辅导，他是一位著名的剑桥辅导教师，比讲师发挥了更重要的作用。尽管查尔斯·巴贝奇、乔治·皮科克和约翰·赫歇尔努力将新的法国数学引入剑桥，但汤姆孙所参加的数学荣誉学位考试的风格仍然有很多不足之处。约翰·赫歇尔和查尔斯·巴贝奇在1825年对磁进行了一些实验，发展了弗朗索瓦·阿拉戈引入的方法，但热、电或磁的内容都没有进入荣誉学位考试的大纲。

汤姆孙于1845年参加了数学荣誉学位考试的最后部分。他毕业获得学士学位，并且是第二名数学荣誉学位考试一等及格者（Wrangler）（在获得一等学位者的名单中排名第二）。进一步的考试使他成为第一位史密斯奖得主，并当选为彼得学院的会士。同样在1845年，汤姆孙阅读了乔治·格林的著作，这对他研究方向产生了重大影响。他对法国方法的兴趣以及父亲的建议，意味着在获得学位后汤姆孙去了巴黎。在那里，他在亨利-维克多·勒尼奥的物理实验室工作，并很快参与了与让-巴蒂斯特·毕奥、奥古斯丁·路易·柯西、约瑟夫·刘维尔、杜马和雅克·夏尔·弗朗索瓦·施图姆的深入讨论。

也许汤姆孙在巴黎最有收获的讨论是与约瑟夫·刘维尔进行的。正是在约瑟夫·刘维尔的要求下，汤姆孙开始尝试将麦可·法拉第、夏尔·奥古斯丁·德·库仑和西莫恩·德尼·泊松关于电学的思想结合起来。‘超距作用’或‘以太’性质的思想，以及‘电流体’的思想，难以统一。存在这样的问题：‘电流体’是否是一个具有流体性质的真正物理实体。汤姆孙被引导去研究物理科学的整个方法论，将理论的‘物理’部分与‘数学’部分区分开来。

1846年，格拉斯哥的自然哲学讲席空缺。汤姆孙的父亲利用他在大学中的影响力帮助儿子成为该职位的主要候选人。汤姆孙从巴黎回到格拉斯哥，并于1846年一致当选为该校自然哲学教授。1847—49年，他与乔治·加布里埃尔·斯托克斯合作进行流体动力学研究，汤姆孙将其应用于电学和原子论。与乔治·加布里埃尔·斯托克斯的这一合作持续了五十多年，期间频繁交换关于科学问题的信件。其中许多信件保存了下来，例如汤姆孙致乔治·加布里埃尔·斯托克斯的407封信和乔治·加布里埃尔·斯托克斯致汤姆孙的249封信的副本已经出版。这些信件中有许多讨论了热理论与流体理论中的数学相似性。例如，乔治·加布里埃尔·斯托克斯在1847年写信给汤姆孙（例如见[11]）：——

适用于热、流体运动和吸引力的数学考虑之间存在着多么密切的关系。

汤姆孙的热力学研究使他在1848年提出了绝对温标。他提出的绝对温标基于他对热理论的研究，特别是萨迪·卡诺提出、后来由埃米尔·克拉佩龙发展的理论。现在所称的开尔文绝对温标，是在能量守恒得到更好理解之后很久才被精确定义的。它的名称来自汤姆孙1892年从英国政府获得的拉格斯开尔文头衔，并因汤姆孙在这篇1848年论文中的提议而以他命名。

汤姆孙关于热的工作及其不足之处，在[16]中有充分描述。作者总结了他的结论：——

……汤姆孙在1849年至1852年间发表了三篇关于热的理论的有影响力的论文。然而，科学史家已经注意到汤姆孙在调和詹姆斯·普雷斯科特·焦耳表述的一个原理与萨迪·卡诺表述的另一个原理时所遇到的困难，以及汤姆孙在计算中所犯的错误。与此同时，鲁道夫·克劳修斯调和了这两个原理，并在1854年推导出了卡诺原理的一个表达式。……对鲁道夫·克劳修斯的推理来说，根本的一点是，他把卡诺原理作为一种“恢复”条件的意义推到了其最终结论。汤姆孙不知怎么竟让“恢复”的意义从他那里溜走了。他的麻烦由此而来。他似乎被自己最初的困难所困扰，以致把重点放在不可逆性和能量守恒上，而遗漏了“其余的一切”。

1852年，汤姆孙观察到如今被称为焦耳-汤姆孙效应的现象，即气体在真空中膨胀时温度下降。焦耳关于热的观念在随后几年里改变了汤姆孙的观点。汤姆孙逐渐相信了热的动力理论，并在1872年写到他自己的观点是如何被引向这一进路的（例如见[1]）：-

……[1847年之前]我并不知道运动正是迄今被称为物质的东西的本质。在1847年于牛津举行的英国协会会议上，我从焦耳那里学到了热的动力理论，并被迫立刻放弃许多关于表面静止现象终极原因的静态成见，随后又逐年放弃其余所有此类成见。

热的动力理论还使汤姆孙想到为电和磁建立一种动力理论。1856年，他把一篇关于这一主题的论文寄给伦敦皇家学会，题为Dynamical illustrations of the magnetic and helicoidal rotary effects of transparent bodies on polarised light。几年后，他用以下的话解释了自己关于电的概念（见[1]）：-

……我们可以设想，电本身不应被理解为物质的一种偶性，而应被理解为物质的本质。无论电是什么，看来相当确定的是，运动中的电就是热；而这种运动中某种旋转轴的一致排列就是磁……

汤姆孙1856年关于电和磁的这项工作很重要，因为正是这些思想引导詹姆斯·克拉克·麦克斯韦发展出他那非凡的电磁学新理论。人们可能会以为汤姆孙会热切支持詹姆斯·克拉克·麦克斯韦的理论，因为汤姆孙自己的工作帮助创造了这一理论，但事实并非如此。汤姆孙有自己的想法，他希望这些想法会导致一种统一理论，而他的想法使他越来越远离接受詹姆斯·克拉克·麦克斯韦的那些想法。汤姆孙于1867年发表的On vortex motion阐述了他的想法。这篇论文开头写道：-

本文的数学工作是为了说明这样一个假设：空间连续地充满一种不可压缩、无摩擦且不受任何力作用的流体，而各种物质现象都仅仅依赖于在这种流体中产生的运动。

然而，汤姆孙最初希望他的理论能够解释电磁学、光、引力和化学过程的愿望逐渐破灭了。在[25]中，作者论证了汤姆孙电磁工作的重要性，尽管它最终失败了：-

我们想强调汤姆孙在电磁场理论中常常被低估的功绩。W 汤姆孙是第一个试图用数学方法处理麦可·法拉第的力线概念的人，他不仅通过他的著作，也通过他的个人倡议，将詹姆斯·克拉克·麦克斯韦引入电磁场问题。

汤姆孙传记的作者[30]提出这样一种观点：在汤姆孙职业生涯的前半段，他似乎不可能犯错，而在后半段，他似乎不可能正确。这似乎过于极端，但汤姆孙拒绝接受原子、反对达尔文的理论、对地球和太阳年龄的错误推测，以及反对卢瑟福的放射性思想，确实使他在职业生涯后期的许多争论中处于失败的一方。

研究过汤姆孙的一些研究贡献之后，让我们评论一下他引入格拉斯哥大学教学中的创新。他把实验室工作引入学位课程，同时使这部分工作与数学方面保持区分。他通过提供奖品来鼓励最优秀的学生。有些奖品授予最好的学生，通过在学生中组织投票来决定获奖者。还有一些奖品由汤姆孙授予他认为最值得的学生。

汤姆孙不仅在他的研究中采取统一的物理世界观，而且把这一点带入他的教学。他的一位学生听过汤姆孙1859—60年的讲座，写道（见[11]）：-

他的冲动是把各种现象联系起来并得出它们背后的原理，这使他对那些仍处于观察阶段、尚未纳入力学定律的科学分支有些不耐烦。因此，他课程中最精彩、最有分量的部分在最后，那时他总结自己的教学并概括能量以及各种物理力之间的关联……

汤姆逊另一项著名的工作是他与彼得·格思里·泰特合作的项目，他们于19世纪60年代初开始撰写那部著名的著作Treatise on Natural Philosophy。他们通过来回邮寄笔记本的方式合作完成这项庞大的工程，汤姆逊设想这部著作将涵盖所有物理理论。原计划写很多卷，但最终只写成了前两卷，涵盖运动学和动力学。这些非凡的卷册成为许多代科学家的标准教材。

汤姆孙最大的名声来自一件我们尚待讨论的事件。他一直对改进物理仪器极感兴趣，汤姆孙设计并实现了许多新装置，其中包括用于跨大西洋海底电缆首次成功持续电报传输的镜式电流计。19世纪50年代中期，汤姆孙加入了一群实业家，参与一个在爱尔兰和纽芬兰之间铺设海底电缆的项目。他在这个项目中担任了多种角色，既是董事会成员，也是电学理论问题的顾问。

负责操作实际事务的电工是E O W Whitehouse，他不顾汤姆孙的建议，坚持使用自己的系统。电缆于1858年成功铺设，前一年的一次尝试因电缆断裂而失败。在最初传输信号遇到困难之后，情况突然明显改善，Whitehouse声称他的系统取得了成功。然而很快人们发现，他用自己的仪器替换了汤姆孙的镜式电流计，Whitehouse、汤姆孙和其他董事之间爆发了激烈的争吵。1865年第三次铺设电缆时完全采用了汤姆孙的仪器，这次证明非常成功，可以快速传输信号。

由于他在跨大西洋电缆方面的工作，汤姆森于1866年被封为爵士，并于1892年被封为拉格斯的开尔文。开尔文是流经格拉斯哥大学校园的河流，而拉格斯是汤姆森在苏格兰海岸建造房屋的城镇。除了名声之外，他参与电报电缆项目还通过他的电缆专利和咨询带来了巨额个人财富。他能够买下一艘126吨的游艇（拉拉 Rookh）以及一栋带有周围庄园的漂亮房子。Glasgow Herald自豪地宣称电缆的成功[10]：-

杰出的电学家汤姆逊教授——若没有他鼓舞人心的天才，这项伟大事业便不会如此轻易地实现——难道不是格拉斯哥人吗？而用于测试和运行电缆的主要电气仪器，难道不是由本城的光学仪器制造商怀特先生制造的——尽管是在汤姆逊教授的指导下？

汤姆逊发表了600多篇论文。他于1851年当选为皇家学会会士，1856年获得其皇家奖章，1883年获得其科普利奖章，并于1890年至1895年担任其主席。除了在皇家学会的活动之外，正如人们对这样一位杰出的苏格兰教授所期望的那样，他多年来一直为爱丁堡皇家学会服务。他曾三次担任该学会主席，第一次是1873年至1878年，第二次是1886年至1890年，第三次是1895年至1907年去世。汤姆逊还担任了第三个学会的主席，他于1871年当选为英国协会 for the Advancement of Science主席。

汤姆逊作为讲师的才能则不那么令人印象深刻[3]：-

作为讲师，他颇容易让自己的主题牵着走。当这种情况发生时，时间限制就变得无关紧要了，而他的听众对他所讲的内容理解甚少，只好满足于钦佩他举止中那种不安分的活泼（他轻微的跛足反而更突出了这一点），以及他沉醉于手头问题错综复杂之处时的那份热切兴致。

William Thomson's father, James Thomson, had originally intended to become a minister of the Presbyterian Church but had opted for an academic career as a mathematician. William's mother died when he was six years old and from that time he was brought up by his father. James Thomson was the professor of engineering in Belfast at the time of William's birth and, when William was eight years old, his father James was appointed to the chair of mathematics at the University of Glasgow. James Thomson was a dominant father who brought his family up in a strict Presbyterian fashion. William's sister wrote of this childhood [5]:-

Our father read to us regularly every Sunday morning some chapters in the Old Testament, and in the evening some in the New.

However, despite his father being very strict he had a very close relationship with William. It was from his father that William learnt mathematics and at a very young age he became an accomplished mathematician with knowledge of the latest developments in the subject.

William attended Glasgow University from the age of 10. This early age is not quite as unusual as one would think, for at that time the universities in Scotland to some extent competed with the schools for the most able junior pupils. Thomson began what we would consider university level work in 1838 when he was 14 years old. In the session 1838-39 he studied astronomy and chemistry. The following year he took natural philosophy courses (today called physics) which included a study of heat, electricity and magnetism. His Essay on the Figure of the Earth won him a gold medal from the University of Glasgow when he was 15 years old and it was a truly remarkable work containing important ideas which Thomson returned to throughout his life.

At the end of session 1839-40 Thomson read Fourier's The Analytical Theory of Heat a work on the application of abstract mathematics to heat flow. He later wrote [10]:-

I took Fourier out of the University Library; and in a fortnight I had mastered it - gone right through it.

In fact there was a strong interest among the lecturers in Glasgow at that time in the French mathematical approach to physical science. In particular the works of Lagrange, Laplace, Legendre, Fresnel and Fourier were treated with "reverence" to use a word which Thomson himself would later use to describe the attitude that his lecturers had towards these French mathematicians. In fact Thomson also read Laplace's Mécanique céleste in session 1839-40 and visited Paris during this session. Wilson, writing in [11], describes Thomson's undergraduate years in Glasgow as follows:-

... from 1838 to 1841, William appears to have become thoroughly familiar with the phenomena of heat, electricity, and magnetism. Meikleham [the professor of natural philosophy] evidently encouraged something of a unified view of these branches of natural philosophy. Not only did his professors put him in touch with much modern experimental and mathematical research, but they also articulated the ideal of mathematising physical theory, even though none of them was himself a master of that craft.

In 1841 Thomson entered Cambridge and in the same year his first paper was published. This paper Fourier's expansions of functions in trigonometrical series was written to defend Fourier's mathematics against criticism from the professor of mathematics at the university of Edinburgh. A more important paper On the uniform motion of heat and its connection with the mathematical theory of electricity was published in 1842 while Thomson was studying for the mathematical tripos examinations at Cambridge.

At Cambridge Thomson was coached by William Hopkins, a famous Cambridge coach who played a more important role than the lecturers. Despite the efforts of Babbage, Peacock and Herschel to introduce the new French mathematics into Cambridge, the style of the Mathematical Tripos taken by Thomson still left much to be desired. Herschel and Babbage had conducted some experiments on magnetism in 1825, developing methods introduced by Arago, but nothing on heat, electricity or magnetism had entered the syllabus of the Tripos.

Thomson took the final part of the Mathematical Tripos examinations in 1845. He graduated with a BA and he was Second Wrangler (ranked second in the list of those obtaining a First Class degree). Further examinations saw him become first Smith's prizeman and he was elected a fellow of Peterhouse. Also in 1845 Thomson read George Green's work which was to have a major influence on the direction of his research. His interest in the French approach, and advice from his father, meant that after taking his degree Thomson went to Paris. There he worked in the physical laboratory of Henri-Victor Regnault and he was soon taking part in deep discussions with Biot, Cauchy, Liouville, Dumas, and Sturm.

Perhaps the most profitable discussions that Thomson had in Paris were with Liouville. It was at Liouville's request that Thomson began to try to bring together the ideas of Faraday, Coulomb and Poisson on electrical theory. Ideas of 'action at a distance' or properties of the 'ether', and ideas of an 'electrical fluid' were difficult to unify. There were problems of whether or not an 'electrical fluid' was an actual physical entity with the properties of a fluid. Thomson was led to study the whole methodology of a physical science, distinguishing 'physical' parts of a theory from 'mathematical' parts.

In 1846 the chair of natural philosophy at Glasgow became vacant. Thomson's father used his influence in the University to help his son become the leading candidate for the post. Thomson returned from Paris to Glasgow and, in 1846, was unanimously elected professor of natural philosophy at the University. In 1847-49 he collaborated with Stokes on hydrodynamical studies, which Thomson applied to electrical and atomic theory. This collaboration with Stokes was to last for over fifty years with frequent letters on scientific matters being exchanged. Many of these letters have survived, for example copies of 407 letters from Thomson to Stokes and 249 letters from Stokes to Thomson have been published. Many of these letters discuss the mathematical similarities in the theory of heat and the theory of fluids. For example Stokes wrote to Thomson in 1847 (see for example [11]):-

What an intimate relation there is between the mathematical considerations which are applicable to heat, fluid motion, and attraction.

The thermodynamical studies of Thomson led him to propose an absolute scale of temperature in 1848. The absolute scale that he proposed was based on his studies of the theory of heat, in particular the theory proposed by Sadi Carnot and later developed by Clapeyron. The Kelvin absolute temperature scale, as it is now known, was precisely defined much later after conservation of energy had become better understood. It derives its name from the title, Baron Kelvin of Largs, that Thomson received from the British government in 1892, and named after Thomson because of his proposal in this 1848 paper.

Thomson's work on heat, and its shortcomings, is described fully in [16]. The author summarises his conclusions:-

... Thomson published between 1849 and 1852 three influential papers on the theory of heat. However, historians of science have already called attention to Thomson's difficulties in reconciling a principle formulated by James Prescott Joule with another principle formulated by Nicolas Leonard Sadi Carnot, and to errors Thomson made in his calculations. In the meantime, Rudolf Julius Emmanuel Clausius reconciled the two principles, and in 1854 he derived an expression for Carnot's principle. ... it was fundamental to Clausius's reasoning that he took to its ultimate consequence the meaning of Carnot's principle as a 'recovery' condition. Thomson somehow let the meaning of 'recovery' escape him. Therefrom came his troubles. He seems to have been so obsessed by his initial difficulties that he put the emphasis on irreversibility and on conservation of energy, missing 'all the rest'.

In 1852 Thomson observed what is now called the Joule-Thomson effect, namely the decrease in temperature of a gas when it expands in a vacuum. Joule's ideas on heat were to change Thomson's views over the years. Thomson came to believe in a dynamical theory of heat and, in 1872, he wrote about how his views were led towards that approach (see for example [1]):-

... [before 1847] I did not ... know that motion is the very essence of what has hitherto been called matter. At the 1847 meeting of the British Association in Oxford, I learned from Joule the dynamical theory of heat, and was forced to abandon at once many, and gradually from year to year all other, statical preconceptions regarding the ultimate causes of apparently statical phenomena.

The dynamical theory of heat led Thomson to also think of a dynamical theory for electricity and magnetism. In 1856 he sent a paper on this subject to the Royal Society of London entitled Dynamical illustrations of the magnetic and helicoidal rotary effects of transparent bodies on polarised light. He explained his notion of electricity in these words a few years later (see [1]):-

... we can conceive that electricity itself is to be understood as not an accident, but an essence of matter. Whatever electricity is, it seems quite certain that electricity in motion is heat; and that a certain alignment of axes of revolution in this motion is magnetism...

This work by Thomson in 1856 on electricity and magnetism is important for it was these ideas which led Maxwell to develop his remarkable new theory of electromagnetism. One might think that Thomson would have eagerly supported Maxwell's theory which his own work had helped to create, but this was not so. Thomson had ideas of his own which he hoped would lead to a unifying theory, and his ideas took him further and further from accepting those of Maxwell. On vortex motion which Thomson published in 1867, set out his ideas. The paper begins:-

The mathematical work of the present paper has been performed to illustrate the hypothesis that space is continuously occupied by an incompressible frictionless fluid acted on by no force, and that material phenomena of every kind depend solely on motions created in the fluid.

However, Thomson's initial hope that his theory could explain electromagnetism, light, gravity, and chemical processes slowly faded. In [25] the author argues for the importance of Thomson's electromagnetic work despite its eventual failure:-

We wish to stress Thomson's often under-estimated merits in the theory of the electromagnetic field. W Thomson was the first who tried to treat mathematically Faraday's conception of lines of force, and he introduced J C Maxwell to the problems of the electromagnetic field not only by his works, but also by his personal initiative.

The author of the biography of Thomson [30], puts forward the view that during the first half of Thomson's career he seemed incapable of being wrong while during the second half of his career he seemed incapable of being right. This seems too extreme a view, but Thomson's refusal to accept atoms, his opposition to Darwin's theories, his incorrect speculations as to the age of the Earth and the Sun, and his opposition to Rutherford's ideas of radioactivity, certainly put him on the losing side of many arguments later in his career.

Having studied some of Thomson's research contributions, let us comment on the innovations he introduced into teaching at the University of Glasgow. He introduced laboratory work into the degree courses, keeping this part of the work distinct from the mathematical side. He encouraged the best students by offering prizes. Some prizes were awarded to the best student, a vote being organised among the students to determine the recipient. There were also prizes which Thomson gave to the student that he considered most deserving.

Not only did Thomson take a unified view of the physical world in his research, but he carried this into his teaching. One of his students, who attended Thomson's 1859-60 lectures, wrote (see [11]):-

His impulse was to correlate phenomena and arrive at the principle underlying them, and this gave him a certain impatience with branches of science which were still in the observational stage, and not yet come under mechanical laws. Hence the most brilliant and weighty part of his course was at the end, when he summed up his teaching and generalised energy, and the correlation of the physical forces...

Another of Thomson's famous pieces of work was his joint project with Tait to produce their famous text Treatise on Natural Philosophy which they began working on in the early 1860s. They worked by posting a notebook back and forward to each other on this huge project which Thomson envisaged as covering all physical theories. Many volumes were intended, but only the first two were ever written which cover kinematics and dynamics. These were remarkable volumes which became the standard texts for many generations of scientists.

Thomson achieved his greatest fame through an event that we have still to discuss. He was always greatly interested in the improvement of physical instrumentation, and Thomson designed and implemented many new devices, including the mirror-galvanometer that was used in the first successful sustained telegraph transmissions in transatlantic submarine cable. Thomson had joined a group of industrialists in the mid 1850s on a project to lay a submarine cable between Ireland and Newfoundland. He played several roles in this project, being on the board of directors and also being an advisor on theoretical electrical matters.

The electrician who was in charge of the practical side of the operation was E O W Whitehouse, who insisted on using his own system against Thomson's advice. The cable was successfully laid in 1858, an attempt having failed the previous year when the cable broke. After initial difficulties with transmitting a signal, there was a sudden marked improvement and Whitehouse claimed success for his system. However it was soon discovered that he had substituted Thomson's mirror-galvanometer for his own instruments and there was a furious row between Whitehouse, Thomson and the other directors. Thomson's instruments were fully used for the third attempt at laying a cable in 1865 and this proved highly successful with rapid transmission of signals possible.

For his work on the transatlantic cable Thomson was knighted in 1866 and made Baron Kelvin of Largs in 1892. The Kelvin is the river which runs through the grounds of Glasgow University and Largs is the town on the Scottish coast where Thomson built his house. As well as fame, his participation in the telegraph cable project led to a large personal fortune brought about by his cable patents and consulting. He was able to buy a 126-ton yacht (the Lalla Rookh) as well as a fine house with surrounding estate. The Glasgow Herald proudly claimed the success of the cable [10]:-

Is Professor Thomson, the distinguished electrician, without whose inspiring genius this great business had not been so easily achieved, not a Glasgow man? And were the principal electrical instruments employed in testing and working the cable not manufactured by Mr White, the optician of this city, though under Professor Thomson's directions?

Thomson published more than 600 papers. He was elected to the Royal Society in 1851, received its Royal Medal in 1856, received its Copley Medal in 1883 and served as its president from 1890 to 1895. In addition to his activities with the Royal Society, as one would expect of such an eminent Scottish professor, he served the Royal Society of Edinburgh over many years. He served three terms as president of this Society, first from 1873 to 1878, for the second time from 1886 to 1890, and for the third time from 1895 until his death in 1907. Thomson served as president of yet a third society when he was elected as president of the British Association for the Advancement of Science in 1871.

Thomson's ability as a lecturer was less impressive [3]:-

As a lecturer he was rather prone to let his subject run away with him. When this happened, limits of time became of small account, and his audience, understanding but little of what he was saying, were feign to content themselves with admiring the restless vivacity of his manner (which was rather emphasized than otherwise by the slight lameness from which he suffered) and the keen zest with which he revelled in the intricacies of the matter in hand.