William Thomson, 1st Baron Kelvin (26 June 182417 December 1907)
Born in Belfast, he was for 53 years the professor of Natural Philosophy at the University of Glasgow, where he undertook significant research on the mathematical analysis of electricity, was instrumental in the formulation of the first and second laws of thermodynamics, and contributed significantly to unifying physics, which was then in its infancy of development as an emerging academic discipline. He received the Royal Society's Copley Medal in 1883 and served as its president from 1890 to 1895. In 1892 he became the first scientist to be elevated to the House of Lords. The Joule–Thomson effect is also named in his honour.
Kelvin worked closely with the mathematics professor Hugh Blackburn in his work. He also had a career as an electrical telegraph engineer and inventor which propelled him into the public eye and earned him wealth, fame and honours. For his work on the transatlantic telegraph project, he was knighted in 1866 by Queen Victoria, becoming Sir William Thomson. He had extensive maritime interests and worked on the mariner's compass, which previously had limited reliability.
Kelvin was ennobled in 1892 in recognition of his achievements in thermodynamics, and of his opposition to Irish Home Rule, becoming Baron Kelvin, of Largs in the County of Ayr. The title refers to the River Kelvin, which flows near his laboratory at the University of Glasgow's Gilmorehill home at Hillhead. Despite offers of elevated posts from several world-renowned universities, Kelvin refused to leave Glasgow, remaining until his retirement from that post in 1899. In 1904 he became Chancellor of the University of Glasgow.
William and his elder brother James were tutored at home by their father while the younger boys were tutored by their elder sisters. James was intended to benefit from the major share of his father's encouragement, affection and financial support and was prepared for a career in engineering.
In 1832 his father was appointed professor of mathematics at the University of Glasgow, and the family moved there in October 1833. The Thomson children were introduced to a broader cosmopolitan experience than their father's rural upbringing, spending mid-1839 in London, and the boys were tutored in French in Paris. Much of Thomson's life during the mid-1840s was spent in Germany and the Netherlands. Language study was given a high priority.
His sister, Anna Thomson, was the mother of the physicist James Thomson Bottomley.
Youth
thumb|left|upright=0.8|William Thomson, aged 22
thumb|The [[meander of the River Kelvin containing the Neo-Gothic Gilmorehill campus of the University of Glasgow designed by George Gilbert Scott, to which the university moved in the 1870s (photograph 1890s)]]
Thomson attended the Royal Belfast Academical Institution, where his father was a professor of Mathematics in the university department. In 1834, aged 10, he began studying at the University of Glasgow, not out of any precociousness; the university provided many of the facilities of an elementary school for able pupils, and this was a typical starting age. In school, he showed a keen interest in the classics along with his natural interest in the sciences. At age 12 he won a prize for translating Lucian of Samosata's Dialogues of the Gods from Ancient Greek to English.
In the academic year 1839/1840, Thomson won the class prize in astronomy for his "Essay on the figure of the Earth" which showed an early facility for mathematical analysis and creativity. His physics tutor at this time was David Thomson. Throughout his life, he would work on the problems raised in the essay as a coping strategy during times of personal stress. On the title page of this essay Thomson wrote the following lines from Alexander Pope's "An Essay on Man". These lines inspired Thomson to understand the natural world using the power and method of science:
Thomson became intrigued with Joseph Fourier's Théorie analytique de la chaleur (The Analytical Theory of Heat). He committed himself to study the "continental" mathematics resisted by a British establishment still working in the shadow of Sir Isaac Newton. Unsurprisingly, Fourier's work had been attacked by domestic mathematicians, Philip Kelland authoring a critical book. The book motivated Thomson to write his first published scientific paper under the pseudonym P.Q.R., defending Fourier, which was submitted to The Cambridge Mathematical Journal by his father. A second P.Q.R. paper followed almost immediately.
While on holiday with his family in Lamlash in 1841, he wrote a third, more substantial P.Q.R. paper On the uniform motion of heat in homogeneous solid bodies, and its connection with the mathematical theory of electricity. In the paper he made remarkable connections between the mathematical theories of thermal conduction and electrostatics, an analogy that James Clerk Maxwell was ultimately to describe as one of the most valuable science-forming ideas.
Cambridge
William's father was able to make a generous provision for his favourite son's education and, in 1841, installed him, with extensive letters of introduction and ample accommodation, at Peterhouse, Cambridge. While at Cambridge, Thomson was active in sports, athletics and sculling, winning the Colquhoun Sculls in 1843. He took a lively interest in the classics, music, and literature; but the real love of his intellectual life was the pursuit of science. The study of mathematics, physics, and in particular, of electricity, had captivated his imagination. Under the tuition of William Hopkins, in 1845 Thomson graduated as second wrangler. He also won the first Smith's Prize, which, unlike the tripos, is a test of original research. Robert Leslie Ellis, one of the examiners, is said to have declared to another examiner "You and I are just about fit to mend his pens." He was the fourth recipient of The William Hopkins Prize (1876), awarded by the Cambridge Philosophical Society for invention or discovery.
In 1845 he gave the first mathematical development of Michael Faraday's idea that electric induction takes place through an intervening medium, or "dielectric", and not by some incomprehensible "action at a distance". He also devised the mathematical technique of electrical images, which became a powerful agent in solving problems of electrostatics, the science which deals with the forces between electrically charged bodies at rest. It was partly in response to his encouragement that Faraday undertook the research in September 1845 that led to the discovery of the Faraday effect, which established that light and magnetic (and thus electric) phenomena were related.
He was elected a fellow of St Peter's (as Peterhouse was often called at the time) in June 1845. On gaining the fellowship, he spent some time in the laboratory of the celebrated Henri Victor Regnault, at Paris; but in 1846 he was appointed to the chair of natural philosophy at the University of Glasgow. At age 22 he found himself wearing the gown of a professor in one of the oldest universities in the country and lecturing to the class of which he was a first year student a few years before.
Thermodynamics
By 1847 Thomson had already gained a reputation as a precocious and maverick scientist when he attended the British Association for the Advancement of Science annual meeting in Oxford. At that meeting, he heard James Prescott Joule making yet another of his, so far, ineffective attempts to discredit the caloric theory of heat and the theory of the heat engine built upon it by Sadi Carnot and Émile Clapeyron. Joule argued for the mutual convertibility of heat and mechanical work and for their mechanical equivalence.
Thomson was intrigued but sceptical. Though he felt that Joule's results demanded theoretical explanation, he retreated into an even deeper commitment to the Carnot–Clapeyron school. He predicted that the melting point of ice must fall with pressure, otherwise its expansion on freezing could be exploited in a perpetuum mobile. Experimental confirmation in his laboratory did much to bolster his beliefs.
In 1848, he extended the Carnot–Clapeyron theory further through his dissatisfaction that the gas thermometer provided only an operational definition of temperature. He proposed an absolute temperature scale in which "a unit of heat descending from a body A at the temperature T° of this scale, to a body B at the temperature (T−1)°, would give out the same mechanical effect [work], whatever be the number T." Such a scale would be "quite independent of the physical properties of any specific substance." By employing such a "waterfall", Thomson postulated that a point would be reached at which no further heat (caloric) could be transferred, the point of absolute zero about which Guillaume Amontons had speculated in 1702. "Reflections on the Motive Power of Heat", published by Carnot in French in 1824, the year of Lord Kelvin's birth, used −267 as an estimate of the absolute zero temperature. Thomson used data published by Regnault to calibrate his scale against established measurements.
In his publication, Thomson wrote:
—But a footnote signalled his first doubts about the caloric theory, referring to Joule's very remarkable discoveries. Surprisingly, Thomson did not send Joule a copy of his paper, but when Joule eventually read it he wrote to Thomson on 6 October, claiming that his studies had demonstrated conversion of heat into work but that he was planning further experiments. Thomson replied on 27 October, revealing that he was planning his own experiments and hoping for a reconciliation of their two sides.
Thomson returned to critique Carnot's original publication and read his analysis to the Royal Society of Edinburgh in January 1849, still convinced that the theory was fundamentally sound. However, though Thomson conducted no new experiments, over the next two years he became increasingly dissatisfied with Carnot's theory and convinced of Joule's. In February 1851 he sat down to articulate his new thinking. He was uncertain of how to frame his theory, and the paper went through several drafts before he settled on an attempt to reconcile Carnot and Joule. During his rewriting, he seems to have considered ideas that would subsequently give rise to the second law of thermodynamics. In Carnot's theory, lost heat was absolutely lost, but Thomson contended that it was "lost to man irrecoverably; but not lost in the material world". Moreover, his theological beliefs led Thomson to extrapolate the second law to the cosmos, originating the idea of universal heat death.
Compensation would require a creative act or an act possessing similar power, Thomson also formulated the heat death paradox (Kelvin's paradox) in 1862, which uses the second law of thermodynamics to disprove the possibility of an infinitely old universe; this paradox was later extended by William Rankine.
In final publication, Thomson retreated from a radical departure and declared "the whole theory of the motive power of heat is founded on ... two ... propositions, due respectively to Joule, and to Carnot and Clausius." Thomson went on to state a form of the second law:
In the paper, Thomson supports the theory that heat was a form of motion but admits that he had been influenced only by the thought of Sir Humphry Davy and the experiments of Joule and Julius Robert von Mayer, maintaining that experimental demonstration of the conversion of heat into work was still outstanding. As soon as Joule read the paper he wrote to Thomson with his comments and questions. Thus began a fruitful, though largely epistolary, collaboration between the two men, Joule conducting experiments, Thomson analysing the results and suggesting further experiments. The collaboration lasted from 1852 to 1856, its discoveries including the Joule–Thomson effect, sometimes called the Kelvin–Joule effect, and the published results did much to bring about general acceptance of Joule's work and the kinetic theory.
Thomson published more than 650 scientific papers and applied for 70 patents (not all were issued).
Transatlantic cable
Calculations on data rate
Though eminent in the academic field, Thomson was obscure to the general public. In September 1852, he married childhood sweetheart Margaret Crum, daughter of Walter Crum; but her health broke down on their honeymoon, and over the next 17 years Thomson was distracted by her suffering. On 16 October 1854 George Gabriel Stokes wrote to Thomson to try to re-interest him in work by asking his opinion on some experiments of Faraday on the proposed transatlantic telegraph cable.
Faraday had demonstrated how the construction of a cable would limit the rate at which messages could be sent - in modern terms, the bandwidth. Thomson jumped at the problem and published his response that month. He expressed his results in terms of the data rate that could be achieved and the economic consequences in terms of the potential revenue of the transatlantic undertaking. In a further 1855 analysis, Thomson stressed the impact that the design of the cable would have on its profitability.
Thomson contended that the signalling speed through a given cable was inversely proportional to the square of the length of the cable. Thomson's results were disputed at a meeting of the British Association in 1856 by Wildman Whitehouse, the electrician of the Atlantic Telegraph Company. Whitehouse had possibly misinterpreted the results of his own experiments but was doubtless feeling financial pressure as plans for the cable were already well under way. He believed that Thomson's calculations implied that the cable must be "abandoned as being practically and commercially impossible".
Thomson attacked Whitehouse's contention in a letter to the popular Athenaeum magazine, pitching himself into the public eye. Thomson recommended a larger conductor with a larger cross section of insulation. He thought Whitehouse no fool and suspected that he might have the practical skill to make the existing design work. Thomson's work had attracted the attention of the project's undertakers. In December 1856, he was elected to the board of directors of the Atlantic Telegraph Company.
Scientist to engineer
Thomson became scientific adviser to a team with Whitehouse as chief electrician and Sir Charles Tilston Bright as chief engineer, but Whitehouse had his way with the specification, supported by Faraday and Samuel Morse.
thumb|upright|William Thomson's telegraphic syphon recorder, on display at Porthcurno Telegraph Museum, in January 2019
Thomson sailed on board the cable-laying ship in August 1857, with Whitehouse confined to land owing to illness, but the voyage ended after when the cable parted. Thomson contributed to the effort by publishing in the Engineer the whole theory of the stresses involved in the laying of a submarine communications cable, showing when the line is running out of the ship, at a constant speed in a uniform depth of water, it sinks in a slant or straight incline from the point where it enters the water to that where it touches the bottom.
Thomson developed a complete system for operating a submarine telegraph that was capable of sending a character every 3.5 seconds. He patented the key elements of his system, the mirror galvanometer and the siphon recorder, in 1858. Whitehouse still felt able to ignore Thomson's many suggestions and proposals. It was not until Thomson convinced the board that using purer copper for replacing the lost section of cable would improve data capacity, that he first made a difference to the execution of the project.
The board insisted that Thomson join the 1858 cable-laying expedition, without any financial compensation, and take an active part in the project. In return, Thomson secured a trial for his mirror galvanometer, which the board had been unenthusiastic about, alongside Whitehouse's equipment. Thomson found the access he was given unsatisfactory, and the Agamemnon had to return home following a disastrous storm in June 1858. In London, the board was about to abandon the project and mitigate their losses by selling the cable. Thomson, Cyrus W. Field and Curtis Lampson argued for another attempt and prevailed, Thomson insisting that the technical problems were tractable. Though employed in an advisory capacity, Thomson had, during the voyages, developed a real engineer's instincts and skill at practical problem-solving under pressure, often taking the lead in dealing with emergencies and being unafraid to assist in manual work. A cable was completed on 5 August.
Disaster and triumph
Thomson's fears were realised when Whitehouse's apparatus proved insufficiently sensitive and had to be replaced by Thomson's mirror galvanometer. Whitehouse continued to maintain that it was his equipment that was providing the service and started to engage in desperate measures to remedy some of the problems. He fatally damaged the cable by applying a "jolt" of high voltage electricity from -long induction coils on shore at Valentia Island, the eastern landfall of the cable.