Lectures on some recent advances in physical science with a special lecture on force

Front matter

CORNELL

UNIVERSITY

LIBRARY

Preface To Second Edition

In preparing a Second Edition for the press, I have adhered to my original plan of publishing these Lectures just as they were taken down by the shorthand writers. I have, however, altered here and there a mere word or two, and in a few places, where it appeared to be called for, I have added an explanatory sentence.

Herr Wertheim, who is engaged in translating the work into German, has kindly called my attention to an article in the second edition of Clausius' Mechanische Wdrmetheorie which has reference to a discussion raised by that author in Pogg. Ann. (1872.) Three letters were written by Clausius and three by myself — all of which appeared in the Phil. Mag. (see foot-note to p. 118.) The first alone of my letters was sent to Professor Poggendorff, as I did not wish to occupy more than was absolutely necessary of his space with what I could not help anticipating would be a perfectly fruitless controversy.

I disclaimed at once and utterly the imputation of irritation made by Clausius. I simply said, in answer

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to his charges of deliberate suppression, etc., 'Such language may amaze and amuse, it is too reckless to produce irritation.' And in my last letter in the Phil. Mag. (September 1872) I described my position as follows : —

Professor Clausius has so long, and so repeatedly, claimed as his - own the correct proof of the Second Law of Thermodynamics, that no one can be astonished to find him unwilling to allow that his claims are unfounded.

But I must protest against his making accusations of deliberate suppression, etc., and repeating them in the indirect and ofifensive form of a statement that he did not apply them to Sir W. Thomson.

There has been nothing in the language I have employed, even had it been tenfold more pointed, which is not admissible in fair and temperate discussion. I have made no charges (though strongly tempted to do so by Professor Clausius' first letter), I have simply examined historical facts and given what appears to me to be the natural and inevitable conclusion from them. But, after having taken every precaution to insure accuracy, to be first accused of deliberate suppression, and then to be told that the tone of my far too mild reply renders it impossible for Professor Clausius to continue the discussion, is a trifle too much.

In common with all the scientific friends I have consulted, I am unable to perceive that Professor Clausius has ' refuted ' any one of my former remarks, or that he is likely to be able to refute any of the others — though he says it can be easily done. Let Professor Clausius attempt the refutation, if he thinks proper to do so : but in future it is to be hoped he will leave ofifensive and unjust charges unmade. As I consider that my last letter contains all that it is necessary for the present to say for my own view of the matter, I shaU continue to maintain and to promulgate the opinions therein expressed, until convinced by argument, not by personalities, that they are incorrect or insufficient.

Professor Clausius now says that I have shirked the two main charges brought against me. I am not of

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that opinion, but I shall endeavour to make up for any possible defect of that kind. I cannot now go fully into the whole matter, but as some parts of the charges are, if well founded, applicable to this work, I shall allude to them here.

Clausius' first charge is that ' there can be no doubt that my Sketch of Thermodynamics^ owed its origin principally to my purpose of claiming the Mechanical Theory of Heat as far as possible, for the English (British) nation,' and he adds that he ' can bring forward the most definite grounds for this opinion.' I am, indeed, curious to know what these grounds can be, seeing that the deduction to which they have led my assailant is so entirely at variance with my own recollections. So far as I am aware, my book owed its origin to the desire expressed to the Editor of the North British Review, by various scientific or practical men, mainly engineers, that two articles of mine which had appeared in that work should be reprinted, for convenience of reference. As I found that I should thus, by adding a short chapter, make a useful manual for students, I agreed at once to the proposal. There can be no question here as to a view of claiming anything for the British nation.

But perhaps Professor Clausius means that the Review

^ Edinburgh, Edraonston and Douglas, 1868.

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articles were originally written with this view. Here again my memory can recall nothing beyond a request by the Editor that I should review certain works on the Modern Theory of Energy, and specially on the branch of it which relates more particularly to Heat. I found that it was impossible to write articles which should be intelligible to the mass of the readers of the Review unless T were to give them in the main the form of a sketch, partly historical, of the whole subject.

I am not conscious of having anywhere stretched a point to claim for Joule or Thomson what I did not believe to be entirely theirs. On the contrary, I now see that I unwisely, though I thought at the time justly, added in favour of Clausius some paragraphs to an abstract of his work, which, at my request, had been kindly drawn up for me by my friend the late Professor Rankine. I made this request to Rankine because Clausius had, in a private letter to me, protested against some statements in my first Review article. Rankine's acquaintance with the details of Clausius' work was, I knew, at that time much more complete than mine.

This point, however, I shall discuss more fully in a second edition of my Sketch, shortly to be published.

As to the general question of writing too much in British interest, I will content myself with quoting

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part of a diametrically opposite charge lately made against me among others by my friend Professor Challis. He refers particularly to the work entitled The Unseen Universe, but the substance of the charge is general : —

' I think I am right in entertaining the opinion that .... is due to the, overweening estimation in which Englishmen (Britons) not unfrequently hold the scientific productions oi foreigners'

Professor Clausius' second charge is that, in the same book, I attributed an analytical expression of his to Sir William Thomson ; and gave, as my authority, a reference to an article of Thomson's ' in which neither that expression nor any expression of like meaning could be found.' My reference is quite correct. This, however, is a purely technical subject, unsuited to the present work, and will be fully, as well as more fitly, discussed in the second edition of my Sketch.

I cannot say , more here in answer to Professor Clausius. His valuable services to mathematical physics entitle him to an amount of consideration which can be extended to but few of my other assailants.

Professor ZoUner has seen fit to renew (though on somewhat altered grounds) the attack for which he was so deservedly and so summarily castigated by Helmxii PREFACE.

holtz in the Preface ^ to the German edition of Thomson and Tait's Natural Philosophy. There is not much use in arguing with a man who makes me out to be ignorant, not only of Latin but, even of the very first Law of Motion ! The grave error of which he so complacently convicts me {Pogg. Ann'. 1876, No. 7), does not exist, as in fact is evident from my words, even as he quotes them, though he omits the commas in which I enclosed the phrase ' The perpetual motion.' Professor ZoUner should not attempt to criticise such things until he acquires sufficient knowledge of British technical terms to enable him to recognise in the words ' The perpetual motion ' the equivalent (not of ' Die beharrliche Bewegung' but) of 'Das perpetuum mobile! For that this confusion is due to Professor Zollner's imperfect knowledge of English is made evident by the following sentence : — ' So bezeichnet Hr. Tait in seinem oben citirten Werke das Weber'sche Gesetz als die beste aller bisher zur Erklarung der elektrischen Phanomene aufgestellten Hypothesen (the best known complete hypothesis, that of Weber).'

Since this work was published (in April last) my attention has been called to a paper by Mohr,^ which

' Translated by Crura Brown — Nature, 1874.

'^ Ansichten iiter die Natur der Wdrme. Liebig's Annalen, iZvi' Translated in Phil, Mag., August 1876.

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renders almost unnecessary most of what is said in the text about the claims of Mayer's first paper.

Singularly enough, this little writing of Mohr is not even referred to by Mayer, though his much belauded earliest paper appeared only five years later, and in the very same journal. It contains, in a considerably superior form, almost all that is correct in Mayer's paper; and, though it contains many mistakes, it avoids some of the worst of those made by Mayer, especially his false analogy and his cl priori reasoning.

On the other hand, several of the necessary consequences of the establishment of the Undulatory nature of Radiant Heat are well stated ; and the very process (for determining the mechanical equivalent of heat by the two specific heats of air) for which Mayer has received in some quarters such extraordinary praise — though it is in principle, albeit not in practice, utterly erroneous — is here stated much more clearly than it was stated five years later by Mayer.

Still, I have preferred to retain the exposure of these so-called claims, inasmuch as I may thus be spared the necessity for any further discussion of a subject on which most of my opponents are and have been hopelessly in error.

I have been requested to append to this edition th^ Lecture on Force which, at very short notice, I delixiv PREFACE.

vered before the British Association during its recent meeting in Glasgow. The subject is one which falls in naturally with the course of exposition employed in the present volume. In fact, it is briefly treated in the first Lecture of the series. It is a subject of great im^ portance at the present time, though in another century it will probably have lost all but a mere antiquarian interest.

P. G. TAIT.

October 1876.

Preface To First Edition

The following Lectures were given in the spring of 1874, at the desire of a number of my friends, — mainlyprofessional men, — who wished to obtain in this way a notion of the chief advances made in Natural Philosophy since their student days.

The only special requests made to me were, that I should treat fully the modern history of Energy, and that I should publish the Lectures verbatim.

The reader will judge for himself how far the first request has been attended to. As to the second, it is necessary to explain that, being very busy, I had not time to do more than arrange a few notes for each lecture ; so that the course was entirely extempore, and was taken down by excellent short-hand writers.

Besides necessary corrections, only one large change was made in the M.SS., viz., the excision of a great many of those repetitions which are indispensable in extempore lecturing, but are intolerable in a book. Professors Clerk-Maxwell and Balfour Stewart have been kind enough to read the proofs, and to suggest several valuable improvements.

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The work must, however, be regarded as in no sense whatever a finished production, though I hope it will be found not only accurate but also readable. In fact, I could not possibly have found time to rewrite the whole in the form in which I should like to have' presented it for publication ; so that the reader is requested to remember, if he desires to find fault, that the nonremoval of many defects whose correction would have required large changes, was the condition under which alone the book could have appeared. Still, I should not have allowed it to be published had I not been assured by competent judges that in spite of its necessary imperfections it is calculated to be useful.

P. G. TAIT.

College, Edinburgh, February 1876.