To William Thomson¹

Remarks on the Dynamical Theory of Heat. | By JOHN TYNDALL, F.R.S. | To WILLIAM THOMSON, Esq., F.R.S., Professor of Natural Philosophy in the University of Glasgow.

SIR,

THE article in ‘Good Words’² which drew from me the brief remonstrance published in the March Number of the Philosophical Magazine³ bore your name, which preceded, though not by right of the alphabet, that of Professor Tait. From this gentleman’s communication to the Philosophical Magazine of last month,⁴ I learn that it was in compliance with requests made to you that the article in ‘Good Words’ was written. Indeed, irrespective of these considerations, in any article of the kind where your name is associated with that of Prof. Tait, you are sure to be regarded as the ‘principal’. You are the older and more famous man, and it is your behaviour in this controversy, and not that of your colleague, which will interest the scientific world. I trust, therefore, Prof. Tait will see that simple chivalry makes it my duty to decline entering into any contest with him at present; and seeing this, he will, I doubt not, have the grace and modesty to stand aside and allow you and me to settle this affair⁵ between ourselves.

At your request, we are informed, your friend has replied to my “Remarks” both for you and for himself. Doubtless his reply has passed through your hands and received your assent. I may therefore, I hope, regard it as your reply, and deal with it accordingly. You open thus:—“I think it right at starting to call Prof. Tyndall’s attention to the fact that, in the Philosophical Magazine (1862, vol. xxiv. P. 65), he has published the following words:—‘I do not think a greater disservice could be done to a man of science than to overstate his claims: such overstatement is sure to recoil to the disadvantage of him in whose interest it is made.’” There is surely nothing in these words of which an honest man need be ashamed. They are, I submit, sensible words; and were they not my words, I should on various grounds strongly recommend them to your own particular attention. But besides reviving my memory of these words, you remind me “that any unpleasant results which may follow from the course which he [Prof. Tyndall] has pursued are, by his own acknowledgement, to be laid to his charge.”

I hope you will forgive me if I now remind you that, in conducting this correspondence, it is extremely desirable that each of us should endeavor to make his meaning clear. This ‘reminder’ of yours is by no means clear. As a deduction it would be illogical, as an assertion it would be untrue. If in such a simple matter your writing is made difficult of comprehension, how am I to seize your meaning when you come to deal with a really difficult subject? Let each of us try then to render his meaning unmistakable; but this once done, let neither of us seek to divert the words of the other from their plain and obvious sense. This course will shorten controversy, and make the world feel that we mean fairly by each other. In your last communication you write thus:—“A journal which contains in nearly every Number a scientific paper by yourself [Sir David Brewster,⁶ to whom Prof. Tait addresses his communication], Forbes, Herschel,⁷ or Piazzi Smyth,⁸ can surely not be regarded as unsuitable for a paper on ‘Energy.’” Did I say it was? Did I not rather state that it was both laudable and desirable that men in your high positions should instruct the readers of ‘Good Words;’ and I may here add, what I am known to have stated a hundred times, that in my opinion it would be an incalculable boon to English society if our best men could be prevailed upon to write our scientific manuals, and to teach the public through our leading magazines. But I also said, and I think rightly, that ‘Good Words’ is not the place to give vent to insinuations prejudicial to the character of a scientific fellow-worker. And inasmuch as I know that the character you impugn is of a quality to defy all your attacks, if only openly made, it is only natural that I should invite you to make your charges against it in the presence of a jury competent to understand your evidence.

With regard to the publication of my lecture on Force,⁹ the course pursued was this: the abstract of the lecture was published, as all such abstracts are, in the ‘Proceedings of the Royal Institution,’¹⁰ and it was transferred thence to the Philosophical Magazine.¹¹ With its further publication I had nothing whatever to do. Until you informed me of the fact, I did not know that the lecture had been honoured by admission into the ‘Illustrated London News,’¹² the ‘Engineer,’¹³ and ‘Macmillan’s Magazine.’¹⁴ The gentleman¹⁵ whom you denominate my ‘pupil’ is quite unknown to me. But even had I written my abstract expressly for any of these journals, there would, I submit, be nothing unworthy or inconsistent in the act; for the lecture contains imputations upon no man’s character. My object in giving the lecture was not to defame anybody, but to raise a noble and a suffering man¹⁶ to the position which I believed his labours entitled him to occupy, and from which I am persuaded your efforts will be unavailing to remove him.

In proof of your acquaintance with Mayer, you refer me to a paper of yours in the Edinburgh Transactions,¹⁷ in which I am informed you give him “the full credit that his scientific claims can possibly be admitted to deserve.” This is an assertion made without knowledge. Regarding Mayer’s labours you knew, I assume, what everybody knew—the contents of his first paper,¹⁸ which, able and important as it is, is in reality nothing more than a preliminary note*.¹⁹ Everybody was acquainted with this paper, because it was published in Liebig’s Annalen:²⁰ and had Mayer’s subsequent memoirs been published in the same way, I do not think you would ever have ventured to provoke this controversy. The contributions from which, in connexion with his first one, Mayer’s merit as a philosopher is to be inferred, were published as separate essays at Heilbronn.²¹ To these essays you never refer, and from your silence I charitably inferred your ignorance of their contents. This, however, does not satisfy you. And yet if I assume that you are acquainted with these memoirs, how am I to reconcile your knowledge with your silence?

You have thought it necessary to refresh my memory on another point which I should willingly have allowed to remain at rest. “Prof. Tyndall,” you say, “is most unfortunate in the possession of a mental bias which often prevents him (as, for instance, in the case of Rendu and Glacier-motion) from recognizing the fact that the claims of individuals whom he supposes to have been wronged*²² have, before his intervention, been fully ventilated, discussed, and settled by the general award of scientific men.” This language, as applied to Mayer, can only spring from ignorance; and as regards Rendu, it would be wise in you to remember that your opinions on this matter are not those of the world. Even among your own countrymen there are persons too just and too free to be warped by a misnamed patriotism, who, in common with the great majority of its readers in other lands, consider that in my work upon the Alps the claims of Rendu have been for the first time fairly set forth.²³ No man, however, can be less persuaded on his own infallibility than I am of mine, and I clearly see the possibility of my having greatly erred in my writings upon glaciers. But I am willing at all events to bring my deeds to the light, so that, whether good or evil, they may be made manifest. I have now to request you to refer me to the passages from my writings on Rendu and Glacier-motion which establish the unfortunate mental bias you have ascribed to me.

It may shorten our correspondence, by making reflexion the precursor of expression, if I here assure you that it is my fixed intention not to permit random assertions to stand in this discussion. What you have the hardihood to affirm, you certainly must have the goodness to prove or the manliness to retract. I ask your proof, then, of the assertion you have made regarding Rendu and Glacier-motion.

After disposing of the matters to which I have had thus far occasion to refer, apparently much to your own satisfaction, you put the following pointed question:—“Does Professor Tyndall know that Mayer’s paper has no claims or novelty or correctness at all, saving this, that by a lucky chance he got an approximation to a true result from an utterly false analogy”? I am able with the utmost sincerity of heart to avow that I did not know anything of the kind, and that you are the first man who has furnished me with this information. I should doubtless stand abashed and confounded at my convicted ignorance were it not that I find myself surrounded by an extremely respectable company who are actually as ill-informed as myself. Permit me to illustrate my meaning. In a discourse delivered at Königsberg²⁴ on the 7th of February, 1854, Prof. Helmholtz analyses that relationship of natural forces which he, in 1847, called the Conservation of Force—a phrase to which you object as inconvenient and erroneous, but which means the same thing as the phrase ‘Conservation of Energy’ which you adopt. This conservation Helmholtz showed to follow directly from the negation of a perpetual motion; and it is with reference to this great principle that he expresses himself in the following words*:²⁵—“The first man who correctly perceived and rightly enunciated the general law of nature (das allgemeine Naturgesetz) which we are here considering, was a German physician, J. R. Mayer, of Heilbronn, in the year 1842. A little later (in 1843) a Dane named Colding²⁶ presented a memoir²⁷ to the Academy of Copenhagen, in which the same law was enunciated….. In England Joule began about the same time to make experiments on the same subject.” You say that you “never intended to hint that Prof. Tyndall could have meant to put Mayer forward as having any claims to this great generalization.” Bad as I am, you would not think of charging me with this grotesque folly. And still for nine years Helmholtz, who was a master in this field before you ever entered it, has stood self-convicted of this very absurdity.

Let me now refer you to another of my companions in ignorance. On the 7th and 21st of February, 1862, two lectures on the Mechanical Theory of Heat²⁸ were given by M. Verdet before the Chemical Society of Paris^†.²⁹ This philosopher, to whom everybody has hitherto ascribed a thorough knowledge of the literature of science, expresses himself on the subject in hand in the following words:—“Finally, I will terminate this first part of my historic review by calling to mind that Mr. Séguin, in a work published in 1839,³⁰ and devoted more to political economy than to physics, has presented considerations regarding the steam-engine which closely resemble those by which I endeavoured, in our first lecture, to make you comprehend the transformation of heat into mechanical power.”

I should deem it probable that M. Verdet knows as much about the labours of M. Ségun³¹ as you do, and he certainly knows more about those of Mayer. But he does not see in the former the annihilation of the latter. He proceeds thus:—“I now come to the researchers which from 1842 to 1849 definitely founded the science. These researchers are the exclusive work of three men, who without concert, and even without knowing each other, arrived simultaneously in almost the same manner at the same ideas. The priority in the order of publication belongs without any doubt to the German physician Jules Robert Mayer, whose name has occurred so often in these lectures; and it is interesting to know that it was by reflecting on certain observations in his medical practice that he perceived the necessity of an equivalence between work and heat….. He perceived in the act of respiration the origin of the motive power of animals; and the comparison of animals with thermic engines afterwards suggested to him the important principle with which his name will be connected for ever…..We also find,” continues M. Verdet, “in the same memoir (Liebig’s Annalen, 1842) a first determination of the mechanical equivalent of heat, deduced from the properties of gases, which is perfectly exact in principle*.”³² You see then that I am not the only person who has failed to arrive at your remarkable conclusion that “Mayer’s paper has no claims to novelty or correctness at all.”

After referring to M. Colding, M. Verdet passes on to Mr. Joule. “The third inventor,” he says, “of whom it remains for me to speak is Mr. Joule, who perhaps has done most for the demonstration of the principle and for its final adoption. His first investigation, published only in 1843, is incontestably posterior by some months to the first publications of Mayer and Colding^†.³³ All this is certainly very much a variance with your statement in ‘Good Woods.’ “Curiously enough,” you there say, “although similar coincidences are common, while Joule was pursuing and publishing his investigations, there appeared in Germany a paper by Mayer, of Heilbronn. Its title is ‘Bemerkungen über die Kräfte der unbelebten Natur,’ and its date is 1842.” Would you have the goodness to point out a single word regarding the mechanical value of heat, or the mechanical equivalent of heat in any of Mr. Joule’s writings prior to the month of December 1843? If no such word occurs, if Helmholtz and Verdet be correct in assigning this date to the earliest experiments of Mr. Joule on the ‘Mechanical Value of Heat,’ how am I to characterize your statement that it was while Joule was pursuing and publishing his investigations that Mayer’s paper, dated May 1842, appeared? If you should urge that these investigations led Mr. Joule to his experiments on the mechanical equivalent of heat, you simply repeat what I have myself stated in the very lecture which has been the object of your unwarrantable attack.

With reference to the manner in which I have met your insinuations in my brief communication to the Philosophical Magazine, we have the following remarks:’— “I am unwilling to enter upon matters of a more personal character, but it is impossible to pass over the fact that, in answer to an expostulation from Joule (having reference to his lecture), Prof. Tyndall referred (Phil. Mag. 1862, second half year, p. 173) to statements which he had made in a course of lectures which, he now tells us, were completed before he acquired those views of Mayer’s claims to which Joule so naturally objected, and that he now replies to Prof. Thomson and me, not by showing that his lecture, to which we referred, was free from the objections which we urged against it, but by showing that these objections could not be urged against a certain statement which he quotes from a work, not published, but promised for publication.” This reads smart; but my frame of mind disqualifies me from meeting it with mere smartness. In replying to it I do not forget that my aim must not be to satisfy you as to the uprightness of my course of action, but to enable the scientific public to judge between your actions and mine. On my return from Switzerland in 1862, I became acquainted with the “expostulation” to which you refer; and I also found waiting for me a private letter from Mr. Joule,³⁴ reminding me of what he had done in connexion with this subject. In one of my morning lectures given six months previously, I had recognized in the strongest terms the claims of Mr. Joule on the very points to which, in his private note, he had directed my attention. In my answer to his “expostulation” I quoted this lecture, not expecting that Mr. Joule ought to be satisfied with a statement made six months before, but for the purpose of publicly renewing the value of that statement by resubscription to it. This was done in the following words addressed to Mr. Joule:—“Such has been my language regarding you, and to it I still adhere: I trust you find nothing in it which indicates a desire on my part to question your claim to the honour of being the experimental demonstrator of the equivalence of heat and work.” It was in the presence of this statement that you ventured to insinuate in ‘Good Words’ your charge of depreciation and suppression; and it is in the presence of this statement, requoted for your especial information in the March Number of the Philosophical Magazine, that you now dare to reiterate this charge. The quotation from my book will be recognized by the court before which you and I now stand, as springing from the same spirit of goodwill towards Mr. Joule, and the same high appreciation of his services which have marked all that I have said and written regarding him. It is not only ‘now’ that I entertain those feelings, as you intimate in your concluding paragraph, they have always been mine; and they will continue to be mine despite an advocacy on your part so unwise and so unwarranted as to be well calculated to produce a reaction against the man who is unfortunate enough to find in you the assertor of his claims.

Your article in ‘Good Words’ was professedly written to counteract the errors and absurdities of previous writers. “We have aimed,” you say, “at preparing an article which shall at all events be accurate as far as human knowledge now reaches,” or as you more cuttingly express it in reference to my poor lecture, you “seized the opportunity of distributing among its [‘Good Words’] 120,000 readers a corrective to the erroneous information which you saw stealing upon them through the medium of popular journals.” Well, let us inquire a little into the quality of the “corrective.” In putting Mr. Joule forward as the founder of the dynamical theory of heat, you write thus:—“In 1843 he (Mr. Joule) published the results of a well-planned and executed series of experiments, by which he ascertained that a pound of water is raised one degree Fahrenheit in temperature by 772 foot-pounds of mechanical work done upon it. In other words, if a pound of water fall from a height of 772 feet, and the kinetic energy thus acquired in the form of ordinary motion be entirely transformed into the kinetic energy of heat, the water will be one degree hotter than before its fall.” You here prove yourself to be as ill-informed regarding the labours of Joule as you are regarding those of Mayer. It was in 1849, and not in 1843, that, Mr. Joule proved the mechanical equivalent of heat to be 772 foot-pounds. His determinations of the mechanical equivalent of heat, published in 1843, varied from 1040 to 587 foot-pounds. They were so discordant that nobody attached any value to them. It was with reference to Mr. Joule’s earlier experiments that Helmholtz expressed himself thus, in his celebrated essay ‘Uber die Erhaltung der Kraft,’ published in 1847:—“Joule has examined the quantities of heat generated by the friction of water in narrow tubes, and in a vessel in which the water was set in motion by a kind of turbine. He has found in the first case that the heat which raises 1 lb. of water 1°C. would lift 452 kilogrammes to the height of 1 metre; in the second case he found the weight to be 521 kilogrammes. Nevertheless his methods of experiment correspond too little to the difficulties of the investigation to allow of these results having the least claim to accuracy’*³⁵ (als dass diese Resultate irgendwie auf Genauigkeit Anspruch machen könnten). I translated this paper myself for the ‘Scientific Memoirs^†,’³⁶ and was careful to append to this passage a note to the effect that Helmholtz when he wrote thus was only acquainted with the earlier experiments of Mr. Joule. Judged on broad and liberal grounds, Mr. Joule is worthy of such praise as rarely falls to the lot of a philosopher. He is, in my opinion, the true experimental demonstrator of the dynamical theory of heat. But to write as you write regarding his first experiments is simply to betray a want of acquaintance with the requirements of refined experimental inquiry.

You state in ‘Good Words’ that Mayer’s hypothesis is at best only “approximately” true for air. Yes; but the approximation is so close that it cost Mr. Joule six years of labour, according to his own methods, to arrive at the degree of accuracy attainable by the method of Mayer. You coldly deny to Mayer’s first paper all claim to novelty or correctness; and yet a comparison of that paper^‡37 with the first part of your “corrective” in ‘Good Words’ will show that the ideas which you have there enunciated are the ideas of Mayer. The very illustration which you employ, of stirring water in a basin to produce heat, is an experiment of Mayer’s mentioned in this first paper. In the subsequent portion of the article referred to, you come to what you denominate “the grandest question of all.” You put it thus:— “Whence do we immediately derive all those stores of potential energy which we employ as fuel or food? What produces the potential energy of a loaf or a beefsteak? What supplies the coal and the water-power without which our factories must stop?” These “grandest questions of all’ were asked and answered by Dr. Mayer seventeen years before you wrote your article; and yet you never mention his name^§.³⁸ You proceed, “Whence does the sun produce the energy which he so continuously and liberally distributes?” You then consider the various hypotheses framed to account for the permanence of solar emission, and develop the meteoric theory of the sun’s heat. Mayer did the same fourteen years before you wrote this article in ‘Good Words,’ and six years before you published your earliest paper on the subject in the Edinburgh Transactions.³⁹ There is not an idea of any originality in the whole of that paper that is not to be found in the memoirs of Mayer; and yet you do not give him an iota of credit in this article of yours in ‘Good Words,’ the accuracy of which you have so trumpeted forth. Mayer, moreover, went further than you did, and showed that the heat produced by tidal friction must be generated at the expense of the earth’s rotation. This is but an episode in Mayer’s ‘Essay on Celestial Dynamics,’⁴⁰ but it is eminently illustrative of the clear glance which this hard-working physician had obtained into the system of nature. Here was a phenomenon which had been for centuries the subject of observation, measurement, and calculation; still no astronomer, no mathematician, no natural philosopher perceived its inevitable mechanical effect. But Mayer, following out his own principles, saw and enunciated that the motion of the tides, indefinitely continued, must finally stop the earth’s rotation. Name, if you can the “mathematician or naturalist, from Galileo⁴¹ to Davy,” who ever “elaborated” these things. You cannot do so: and while science lives the name of Mayer will be associated with these questions. In the presence of such facts, it ill becomes you to talk to me of suppression and depreciation. You may send your statements into the world labelled ‘Good Words,’ but the world before which you and I now stand will see that the “trade mark” is incorrect; that if to be pitiful, if to be courteous, if to cherish that charity which thinketh no evil, be the marks of goodness, these utterances of your are not good words, but the reverse. Judged of by the facts, and apart from your own uninformed convictions, they are not even words of truth.

In your last communication you anticipated “unpleasant results,” and, doubtless, taking it for granted that the unpleasantness was to be all on my side, you were good, enough to inform me (still by anticipation) that I had only myself to blame. Certainly it is in the highest degree unpleasant to me to be compelled to write as I have here written. It wastes that commodity which to me is the most precious of all—my time, and it stirs up feelings between you and me which I would make any sacrifice consistent with self-respect to annul. But the responsibility is yours. No taint of personality is to be found in anything that I have ever written regarding you; even when facts were against you I held my peace. When I wrote my brief and temperate remonstrance to the Philosophical Magazine, all that I have stated in this letter was known to me. I then knew, as well as I do now, that your treatment of Mayer could not bear the light of criticism; still my remonstrance breathed no syllable of accusation. My desire was to clear myself, and not to criminate you, trusting that the translations of Mayer’s words now appearing in the Philosophical Magazine would in due time set public opinion right regarding him. I hoped that good sense and gentlemanly feeling wood so far predominate as to induce you to withdraw an accusation which, though vaguely uttered, was offensive. Had you done so, this discussion would have perished in the bud, and I should never have written a sentence which could be personally disagreeable to you. But instead of withdrawing your accusation, you repeat it, and thus compel me in self-defence to lay a true statement of the case before the scientific public, and invoke its judgment between us.

I have the honour to be, Sir, | Your obedient Servant, | JOHN TYNDALL.

Phil. Mag., 25 (1863), pp. 368–78