Biographies of Scientific Men/Kelvin

by Arthur Bower Griffiths

Lord Kelvin

KELVIN

1824-1907

WILLIAM THOMSON (afterwards Baron Kelvin) was born at Belfast on 25th June 1824, and was the son of James Thomson, LL.D., formerly professor of mathematics at the University of Glasgow. At the early age of eleven, Thomson entered Glasgow University, and finally St Peter's College, Cambridge. In 1845 he was second wrangler and first Smith's prizeman. After leaving Cambridge, he went to Paris and studied chemistry under Regnault. In 1846 Thomson was elected to the chair of natural philosophy in Glasgow University, and held the post for over fifty years. In 1841 he published a paper on the "Uniform Motion of Heat in Homogeneous Uniform Bodies." Thomson was a profound mathematician and physicist, "a prince of science and benefactor of the world."

Even at eleven years of age the young philosopher was solving the problem—how long it had taken the earth to cool since it first came together as a white-hot globe: and only a few years ago, he stated that the earth was not more than twenty million years old, and would not probably sustain life more than ten million years longer; for in that time the sun would be cool, and therefore organic life on this planet would be impossible.

In conjunction with the late Professor P. G. Tait, he, in 1867, produced a classical work on Natural Philosophy. He devoted a vast amount of time in studying the constitution of matter—the sizes of atoms and molecules, and the force which holds them together. Thomson came to the conclusion from examining the thickness of the wall of a soap bubble, the electrical action of small copper and zinc discs, the refraction of light, and the dynamical theory of gases, that the molecules of air are about large enough to put twenty-five millions of them in a row an inch long. "Imagine a globe of water six inches in diameter magnified to the size of the earth, and its molecules in the same proportion; then, when the drop had become a world, the individual particle would be about the size of small shot, certainly not larger than a football." These calculations were before the discovery of the corpuscular radiations of radium, polonium, actinum, etc., which the experimental researches of Professor J. J. Thomson, of the Cavendish Laboratory, Cambridge, proved to be at least a thousand times smaller than the chemical atom; although the calculations of Lord Kelvin concerning the atom still remain true. He did not care for the latter-day work with radio-active bodies, and frequently alluded to electrons as "chipped atoms."

The forces of the material universe, such as cohesion, adhesion, heat, electricity, magnetism, etc., engaged the attention of Kelvin. Though the amount of energy in the universe is constant, it is always being degraded from higher to lower forms. This is Kelvin's law of the "dissipation of energy," which means that the universe is not a clock wound up to go for ever. Energy is every moment running down, and sometime in the measureless past must have been started, and sometime in the unbounded future it must be wound up again, or stop for ever.

Kelvin's theory of vortex motions, as applied to atoms and molecules, is of vast importance. It is a type of motion in a frictionless, incompressible, primordial fluid which might account for the known properties of matter.

Many of Kelvin's papers are only understood by expert mathematicians. There is hardly a department in physics which he did not make his own: molecular physics, electricity, dynamics, the theory of gases, heat, thermo-dynamics, the theory of energy, etc.

Kelvin was also a great inventor, and his appliances are manufactured by Messrs James White of Glasgow, who employ nearly two hundred skilled workmen and electricians.

His discovery of the "law of the retardation" of electric currents, and the invention of the mirror galvanometer and the syphon recorder, rendered submarine telegraphy possible.

The Atlantic cables of 1858 and 1865 broke, the latter after a fortnight's use. This, according to the late Mr G. H. Smith, was due to strains caused by the "paying out of the cable from coils instead of from reels. During the gales encountered by the Agamemnon the upper part of the main coil shifted, and became a mere shapeless tangled mass. Kinks were produced, and breakage was the result." Ultimately the cable was laid in 1866, and Thomson received the honour of knighthood.

He invented a mariner's adjustable compass (suitable for iron ships), i.e. the compass was constructed so as to neutralize the effect of terrestrial magnetism on iron. The compass was first adopted by the mercantile service, and afterwards by the Admiralty. At first the Admiralty would not look at Kelvin's compass! It may be mentioned that the same authorities resisted the use of lime-juice for scurvy—and thereby thousands of men lost their lives!

Among Kelvin's inventions are his quadrant electrometer for measuring minute electric currents, his tide-predicting machine, his deep-sea sounder, his kilowatt balance, his multicellular electrostatic voltmeter, etc. Kelvin patented his inventions, and thereby reaped a fine harvest, proceeds of his inventions, for at his death he was worth ₤169,000. He did not look upon it as derogatory for a man of science to reap the pecuniary benefit derived from the sale of the inventions of his own brain; by so doing he was enabled to add considerably to the general store of knowledge.

Kelvin's theory of the "dissipation of energy" was announced in a paper on "The Secular Cooling of the Earth," in 1852. He argued that the earth was a hot body like the sun; that it has gradually cooled, is still cooling; and that ultimately it will become cool to the core: life will then be untenable owing to the lowness of temperature.

In 1885 he delivered the Bakerian lecture on the "Electro-dynamics of Qualities of Metals," and in it is published for the first time his "electric convention of heat." Papers on mathematical and physical subjects flowed from his pen, and his inventions were not less numerous. Kelvin, like Newton, was a profound natural philosopher, and the higher mathematics were as play-things to his gigantic and fertile brain.

Among other papers of Kelvin's may be mentioned: "Rigidity of the Earth," "The Mathematical Theory of Elasticity," "The Thermal Effects of Fluids in Motion," "The Determination of a Ship's Place at Sea from Observation of Altitudes," "Approach caused by Vibration," "An Account of Carnot's Theory of the Motive Power of Heat," "On the Dynamical Theory of Heat," and numerous others are to be found in the Transactions of the Royal Societies of London and Edinburgh. His papers began to appear in book form in 1882.

In 1851 he was elected F.R.S. (along with Huxley and Stokes), and, after having received the Royal and Copley medals, he was in 1890 chosen President of the Royal Society. He was one of the eight foreign associates of the Académic des Sciences; D.C.L. of Oxford, and LL.D. of Cambridge, Edinburgh, and Dublin Universities; and he possessed most of the honours awarded to men of science.

Lord Kelvin was twice married. His first wife, the daughter of Mr Crum, F.R.S., died in 1870, and his second wife was the daughter of the late Mr Blandy of Madeira. For many years Lady Kelvin was his companion and helper; and they sailed in their yacht the Lalla Rookh over many seas, for Lord Kelvin was a navigator as well as a physicist and mathematician.

In 1892 he was made a peer of the realm by Queen Victoria. He was a Knight of the Prussian Order Pour le Mérite, a Grand Officer of the Legion d'Honneur de France, a Commander of the Order of Leopold of Belgium, a Grand Cross of the Victorian Order, a Member of the Order of Merit, etc. As Lord Kelvin left no heir the barony became extinct.

Lord Kelvin was hearty and genial, and generally wore a winning smile; and he was the most modest of great men.

On one occasion he paid a visit with a friend to some well-known electrical works. They were escorted over the workshops by the senior foreman, a man of much intelligence and an enthusiastic electrician. Entirely unaware of his visitor's identity, he minutely explained the details of the plant and machinery, and lectured him in his rôle of layman quite professionally. Lord Kelvin's friend was on the point of interrupting several times, but an amused signal from the great master of electricity kept him silent. When the tour of inspection was complete, Lord Kelvin quietly turned to the foreman and asked, "What, then, is electricity?" This was a poser for the man, who, somewhat shamefacedly, confessed that he could not say. "Well, well," said Lord Kelvin gently, "that is the only thing about electricity which you and I do not know."

Lord Kelvin was the greatest teacher of physics of his day, but his lectures were never simple; in fact, his "popular addresses" were more suitable for wranglers than anybody else. His subjects were so simple to him that he frequently overlooked the fact that he took his audience clean out of their depth. He was essentially a teacher of teachers.

In 1896 Lord Kelvin celebrated the jubilee of his professorship at the Glasgow University, and on this occasion men of science from all parts of the world did honour to the great physicist; and he was presented with the Arago gold medal by the Académie des Sciences. Numerous addresses were presented to him from the various universities, academies, and societies of the world, and when thanking the company for the addresses, he remarked:—

You heap coals of fire on my head; you reward me for having enjoyed for fifty years the privilege of spending my time in the work most congenial to me, and in the happiest of surroundings. You could not do more for me if I had spent my life in hardships and dangers, fighting for my country, or struggling to do good among masses of our population, or working for the benefit of the people in public duty voluntarily accepted.

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I feel profoundly grateful; but when I think how infinitely little is all that I have done, I cannot feel pride—I only see the great kindness of my scientific comrades, and of my friends in crediting me with too much. One word characterizes the most strenuous of the efforts for the advancement of science that I have made during fifty-five years, and that word is failure. I know no more of electric and magnetic force, or of the relations between ether, electricity, and ponderable matter, or of chemical affinity, than I knew and tried to teach fifty years ago in my first session as professor. Something of sadness must come of failure; but in the pursuit of science inborn necessity to make the effort brings with it much of the "certaminus gaudia," and saves the naturalist from being wholly miserable, perhaps enables him to be fairly happy in his daily work. And what splendid compensations for philosophic failures have we had in the admirable discoveries by observation and experiment of the properties of matter, and in the exquisitely beneficent applications of science to the use of mankind, with which these fifty years have so abounded.

Two lessons are derived from the life-work of such a man as Lord Kelvin. The theoretical speculations of the philosopher, and the practical inventions of the scientist. Science must, however, in the main be directed to the actual service of man in his daily life. Science largely determines national prosperity; and in this respect Lord Kelvin's inventions are of the highest order of usefulness. Not only Atlantic telegraphy, the adjustable compass, but the scullery tap came under his inventive genius. Apply your knowledge! It is of little use if not capable of application. That was the law of Kelvin's life. In addition to inventions, he soared into the profoundest speculations of philosophy: the birth of worlds, the size of atoms, the cooling of the earth, etc., all engaged his attention.

If the laws of gravitation, and the decomposition of light by the prism, were the chief achievements of the immortal Newton; the magnitudes and motions of atoms, the theory of the age of the world, and oceanic telegraphy, were the principal discoveries of the immortal Kelvin.

A mere material universe, however, did not satisfy Lord Kelvin. There are such things as intelligence, volition, and emotion; the power to reason, the capacity to distinguish good and evil, and taste to admire the beautiful, which cannot be expressed in terms of length, breadth, and depth; or as qualities of solids, or liquids, or gases. There are life and mind; these no knowledge of matter has explained. "Proofs of intelligent and benevolent design lie all around us," said Kelvin. Things must be as they are either by chance, necessity, or design. Chance is out of the question, unthinkable. Grant that the properties of things, like those of numbers, for instance, could not be otherwise, have been eternally as they now exist—impossible as the supposition is—how came the elements of this world to be distributed as they are and in such proportions? Why gold rarer than iron, and iron than clay? Why the optical rotation of life-compounds (such as tartaric acid, lactic acid, etc.), and not of the synthetical acids? Why a globe adapted not merely in the quality of its materials but in their quantity and distribution to the wants of living beings and to their evolution? Kelvin answered firmly and unwaveringly: "Because all living things depend on one ever-acting Creator and Ruler."

Lord Kelvin had a limp, which was due to his early enthusiasm for curling. He had the misfortune to break his leg twice on the ice, and a third time it had to be rebroken in order to make a better setting.

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The Manchester philosopher Joule had investigated the phenomena attending the evolution of heat during the passage of a current through an electrolyte, and it was proved that the total quantity of heat could be separated into two parts. "One part was expressible as the result of overcoming ordinary resistance, and the other part was due to chemical changes in the cell. He then determined the quantity of heat evolved, during a given time, in a process of electrolysis by a current of given strength; then, by applying Ohm's law, and the law stated connecting heat with resistance and current, he found the heat which would have been evolved, had a wire with resistance equal to that of the electrolyte been substituted for the electrolyte. The difference between these two quanties of heat is equivalent to the heat which is due to the reverse chemical combination by combustion or other means." The problem was further investigated by Lord Kelvin. He reasoned as follows—: "Let unit quantity of electricity pass through a cell of infinitely small resistance; then, by Joule's law, the work done by the current is equal to E, the electromotive force. But ε gramme of one of the elements of the electrolyte has been electrolyzed, in accordance with Faraday's law. Let θ be the quantity of heat developed by the combination of one gramme of this element to reproduce the electrolyte, then, since no work is expended in any other part of the circuit

E = Jεθ, and therefore θ = EJε.

J = the mechanical equivalent of heat."

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Lord Kelvin died on 17th December 1907, the result of a severe chill, and his remains were buried in the nave of Westminster Abbey. It was an ever-memorable occasion, when an enormous concourse of men of science and others attended the funeral. Kelvin's grave is next to that of Sir Isaac Newton, who was buried in 1727. On the gravestone of the latter are the words: "Hic depositum est quod mortale fuit Isaaci Newtoni." Newton's body lay in state in the Jerusalem Chamber, and distinguished men from all parts of Europe came to pay their last respects to the memory of the great British philosopher. Among these was no less a person than Voltaire (1694-1778). He had the greatest admiration for Sir Isaac Newton, and of this great occasion, he wrote that "if all the geniuses of the universe should assemble, Newton would lead the band."^[1]

In the nave of the Abbey, where Kelvin lies buried,^[2] there are the graves of Newton, Darwin, Lyell, Herschel, Hunter, Livingstone, and others—a veritable "Science Corner." With the death of Lord Kelvin disappears one of the grandest figures in the history of science. His country honoured itself in recognizing his merits, and England has every reason to bewail her loss, for however rich she may be in distinguished men, she cannot fail to recognize that the loss of Lord Kelvin is an irreparable one.

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Although Lord Kelvin did not care for the present-day work on electrons or fractional atoms and the crumbling of the elements, his mind was free from bias; and he viewed the brilliant researches of J. J. Thomson, Ramsay, and others with the keen eye of the philosopher. The mutability of the elements by Ramsay is most wonderful. He has found that the radium emanation develops into helium, and when the same emanation is passed through water it changes into neon. If it is passed through a solution of a salt of copper, it resolves itself into argon; and when copper is acted upon by the radium emanation it is converted into lithium! Argon, helium, radium, neon, krypton, and xenon are non-valent elements, and as such have not the power of combining with other elements. Thus they appear to be the wreck of the material universe, which seems to be undergoing universal dissolution. In the course of a thousand million years one cannot say what the gold and silver, the copper and lead, and much else of the solid structure of this globe may have become. Another marvellous feature is the unheard-of energies which these fragments of radium set free in their break up. The powers of Nature in this respect astonish us as much as its extent in space and time.

Whether Lord Kelvin could read the future or not as to the drift of modern investigations on electrons and emanation "it would be shallow to believe that such men as Kelvin, with faculty quickened and outlook widened in the high air to which their fame raises them, really discerned no more than we, who have only their written words for authority, can perceive that they discerned. Great position often invests men with a second sight, whose vision they lock up in silence, content with the work of the day."

At the 1903 meeting of the British Association, Kelvin contributed a paper on the subject, of which the following is a résumé:–Radium has been found to emit three types of rays—(1) the α rays, positively electrified and largely stopped by solid, liquid, or gaseous screens; (2) β rays, more penetrative than α and negatively electrified; (3) γ rays, electrically neutral and much more penetrative than either of the other two, passing with but little loss through a lead screen one centimetre thick, which is an almost perfect screen against the other rays. A simple prima facie view was to regard the γ rays as mere vapour of radium; the β rays seem certainly to be atoms of resinous electricity or electrons. The α rays were atoms of molecules of matter, probably atoms of radium, or perhaps molecules of radium bromide. The electro-ethereal hypothesis afforded a ready explanation of the relative penetrating power of the three radiations, and of the fact that each one of them made its existence known to us by conferring electric conductivity on air or on any ordinary gas on which it was present. Taking the γ rays first, we had to explain the free penetration of unelectrified radium molecules through dense liquid and solid matter. An easy assumption sufficed. Let the Boscovichian mutual forces—that was, the chemical affinities and the repulsions—between an atom of radium and the atoms of lead and other permeable substances be absolutely zero or small enough to allow the known permeation. Taking next the a radiation, the apparent great absorption of the vitreous electric emanation from radium was only apparent. It meant that an atom shot from radium with less than its neutralizing quantum of electrons could not go far through a solid or liquid without acquiring the neutralizing quantum. The β absorption might be regarded as probably real. Atoms of resinous electricity shot from radium could not be expected to enter a screen of metal, glass, or wood, or liquid, and leave at the other side, irrespectively of the insulation of the screen and of the radium. The full consideration and experimental investigation of the emission of atoms of resinous electricity from radium hermetically sealed in a glass bulb or tube led to surprising and interesting results. As to the γ rays, there was no difficulty in supposing that non-electrified vapour of radium passed very freely through metals or glass without any electric disturbance. It had been published that loss of weight in the course of a few months had been proved. Returning to Becquerel's original discovery in respect to uranium—the electric conductivity induced in air and other gases by a radio-active substance there was a ready explanation in the resuscitation of the old doctrine of Æpinus. The ordinary thermal motions within any solid, liquid, or gas must cause occasional shootings out of electrons from the substance, and the motion of these electrons, under the influence of electrostatic force, must contribute to the electric conductivity of the gas; must, in fact, constitute all of it which was not due to transport of atoms of the gas carrying less than the neutralizing quantum of electrons. Thus every substance must possess radio-activity,^[3] said Lord Kelvin. Some interesting remarks would be found in the Philosophical Magazine, where it was pointed out that radium was three hundred million times more active than the most active common material yet experimented with.

How was this enormous radio-activity of radium to be accounted for? Lord Kelvin suggested that it might be because it was exceedingly polyelectronic; that the saturating quantum of electrons in an atom of radium might be hundreds or thousands or millions of times as many as those of atoms of ordinary material. But this left the mystery of radium untouched—Curie's discovery that it perpetually emitted heat at a rate of about 90 Centigrade calories per gramme per hour. If emission of heat at this rate went on for little more than a year, or, say, ten thousand hours, there was as much heat as would raise the temperature of 900,000 grammes of water 1° C. It seemed to Lord Kelvin utterly impossible that this could come from a store of energy lost out of a gramme of radium in ten thousand hours. It seemed to him, therefore, absolutely certain that if emission of heat at the rate of 90 calories per gramme per hour, found by Curie at ordinary temperatures, or even at the rate of 38, found by Sir James Dewar and Monsieur Curie from a specimen of radium at the temperature of liquid oxygen, could go on for month after month, energy must somehow be supplied from without, to give the energy of the heat getting into the material of the calorimetric apparatus. It was suggested that somehow ethereal waves might supply energy to the radium while it was giving out heat to the ponderable matter around it. Think of a piece of black cloth hermetically sealed in a glass case and sunk in a glass vessel of water exposed to the sun, and think of another equal and similar glass case containing white cloth submerged in an equal and similar glass vessel of water, similarly exposed to the sun. The water in the former glass vessel would be kept very sensibly warmer than the water in the latter. This was analogous to Curie's first experiment, in which he found the temperature of a thermometer with a little tube containing radium kept beside its bulb in a little bag of soft material to be permanently about 2° C. higher than that of another equal and similar thermometer, similarly packed with a little glass tube not containing radium beside its bulb. By changing the water in the two glass vessels a calorimetric investigation might be made, showing how much heat was given out per hour by the black cloth to the surrounding glass and water. Here thermal energy was communicated to the black cloth by waves of sunlight, and given out as thermometric heat to the glass and water around it. Thus, through the water, there was actually energy travelling inwards, in virtue of waves of light, and outwards through the same space in virtue of thermal conduction. This suggestion respecting radium might be regarded as utterly unacceptable, but, at all events, Lord Kelvin thought it would be conceded that experiments should be made comparing the thermal emission from radium wholly surrounded with thick lead with that found with the surroundings hitherto used. … Such were Lord Kelvin's ideas concerning radium.

1. Voltaire's Éléments de la Philosophie de Newton (1738).
2. The inscription on the stone is "William Thomson, Lord Kelvin, 1824-1907."
3. Even the pigment of Micrococcus glutinis is radio-active; and also the chromoplastids of Helianthus, Verbena, and Geranium. (See A. B. Griffiths' papers in Chemical News, vol. xci. p. 97; Berichte der deutschen chemischen Geselhchaft, vol. xxxvi., p. 3959.)