From C. J. Monro, Esq.

Hadley, Barnet, 3d March 1871.

The Hon. J. W. Strutt, son of Lord Rayleigh, and senior wrangler in 1865, has been meddling with your colours, and has given occasion also to me to do so again. I send a selection of Natures containing him and me, and my old contributions of last year, which, or one of which, you say met Mr. Benson’s approval. Strutt’s last letter ends with a sentence which obliged me to write to him personally; and I could not help saying, with regard to the sentence which begins it, p. 264, that I thought you would object to inferences founded on comparison by contrast, and that the proper way was to compare by matching recognised browns with a compound.

Listing’s paper, mentioned in p. 102, was to me rather a paradox,—I had got to regard the subdivisions of the colour-scale which are assumed in language, as something so arbitrary. If you cared to see it, I have that number of Poggendorff; I think he would hardly agree with your J. J. Müller. I wish you or Benson could eradicate the insane trick of reasoning about colours as identified by their names. People seem to think that blue is blue, and one blue as good as another. Benson’s book I have seen (since I heard of it from you), but not read. His way of mixing by means of a prism is very happy.... I wish, with your new set up box, you would just put the prism observations into relation with the disk ones. It would be very easy. White we have got; and it would only be strictly necessary to determine two other standard colours, such as vermilion or emerald, by reference to the spectrum primaries. You don’t say whether your dwellers in Mesopotamia and elsewhere agree on the whole better or worse than “J” and “K,” who, I suppose, agree for better and for worse. To judge by their case, the discrepancy would be a little diminished by taking as units of colour co-ordinates for any given pair of eyes, not the intensities of the primaries as they appear in the spectrum, but their intensities as they appear in the combination which to that pair of eyes makes (say) white. This amounts to transforming from trilinear to Hamilton’s anharmonic co-ordinates with white for the fourth point,— in the language of “scientific metaphor.” On the other hand, ought not all your co-ordinates to be cooked by multiplying by StartFraction d period scale comma page 68 Over d period wave hyphen length EndFraction?

You know where I learnt scientific metaphor. I have read the address in Section A more than once with much pleasure, and, I hope, profit in proportion. The pleasure, I confess, was with me, as I found it was with Litchfield, partly that of recognising an old well-remembered style, and reflecting that here at least was something which might be “thought to be beyond the reach of change.”... By the way, Boole is “one of the profoundest mathematicians of our time;” but how about “thinkers”? Certainly his expositions of the principle of a piece of mathematics are beautiful up to and, I don’t doubt, beyond my appreciating. But that last chapter of the Laws, etc., from which you quote, with Empedocles and Pseudo-Origen and the rest of them, always seems to me to render a sound as of a largish internal cavity; and the whole book, taken together with his B.S.E. paper on testimony and least squares, presents, I think, too many instances of a particular class of fallacy—I know I am speaking blasphemies, but there would be a strike among the postmen if I put in all the necessary qualifications—too many instances to be got over, not in absolute number if they were of different kinds, for anybody may make mistakes, but too many of one kind. The kind is insufficient interpretation, i.e. letting your equations lead you by the nose. The most serious example,—I maintain it is an example,—is his insisting that his theory of logic is not founded on quantity, so that it furnishes (he holds) an independent foundation for probabilities, independent of the usual quantitative foundation. That this is a fallacy, and that in particular it is an example of the fallacy of insufficient interpretation, is evident surely when you find that, even in the higher case of “secondary” propositions, the elective symbols represent in his own opinion quantities of “time” after all. With regard to the sentence you quote, I am always suspicious of any inclination I may feel to find a question too easy; and, independently of that, your quoting it is itself a staggerer. But the difficulty I confess does strike me as a rather artificial one. There is nothing, scarcely, in which I think Mill is so right and the Hamiltonians so wrong as that question about logic being the laws of thought. Hamilton says as thought, Mill says as valid, and so does Boole and so do you; but if Mill is right, where is the difficulty? Why should the conditions of thinking correctly he inviolable in the sense of not preventing you from thinking incorrectly, provided they are inviolable in the sense of ensuring that you take the consequences if you do? The laws of projection in geometry are inviolable, but nobody ever thought it a paradox that it is possible for a picture to be out of drawing in spite of them, nor is it a paradox that in unfamiliar classes of cases a rigorously accurate piece of perspective looks out of drawing. Perhaps you meant, for I suppose the report in Nature is incomplete, that it was a difficulty to say in what sense mathematical propositions could be said to be certain, considering that one may make mistakes about them. Perhaps something else, which for the above reason or others, is hidden from me.

... By the way, I hope it is true that you are to profess experimental physics at Cambridge, or what I hope comes to the same thing, that you are a candidate.

To C. J. Monro, Esq.

Glenlair, Dalbeattie, 15th March 1871.

I have been so busy writing a sermon on Colour, and Tyndalising my imagination up to the lecture point, that along with other business I have had no leisure to write to any one.

I think a good deal may be learned from the names of colours, not about colours, of course, but about names; and I think it is remarkable that the rhematic instinct has been so much more active, at least in modern times, on the less refrangible side of primary green (lamda equals 510 times 10 Superscript negative 9 Baseline inches right parenthesis.

I am not up in ancient colours, but my recollection of the interpretations of the lexicographers is of considerable confusion of hues between red and yellow, and rather more discrimination on the blue side. Qu. If this is true, has the red sensation become better developed since those days? Benson has a new book, Chapman & Hall, 1871, called Manual of Colour. I think it is a great improvement on the Quarto, both in size and quality. It is the size of this paper I write on.

I have not asked you if you wish to go to sermon on Colour, for I do not think the P. I.[228] a good place to go to of nights, even for strong men. I have, however, some tickets to spare.

The peculiarity of our space is that of its three dimensions none is before or after another. As is x, so is y and so is z.

If you have 4 dimensions this becomes a puzzle, for—first, if three of them are in our space, then which three? Also, if we lived in space of m dimensions, but were only capable of thinking n of them, then 1st, Which n? 2d, If so, things would happen requiring the rest to explain them, and so we should either be stultified or made wiser.

I am quite sure that the kind of continuity which has four dimensions all co-equal is not to be discovered by merely generalising Cartesian space equations. (I don’t mean by Cartesian space that which Spinoza worked from Extension the one essential property of matter, and Quiet the best glue to stick bodies together). I think it was Jacob Steiner who considered the final cause of space to be the suggestion of new forms of continuity.

I hope you will continue to trail clouds of glory after you, and tropical air, and be as it were a climate to yourself. I am glad to see you occasionally in Nature. I shall be in London for a few days next week,—address Athenæum Club.

I think Strutt on sky-blue is very good. It settles Clausius’s vesicular theory,

The Exp. Phys. at Cambridge is not built yet, but we are going to try.

The desideratum is to set a Don and a Freshman to observe and register (say) the vibrations of a magnet together, or the Don to turn a winch, and the Freshman to observe and govern him.

From Professor Tyndall.

Monday.

My dear Maxwell—Why ... did you run away so rapidly. I wished to shake your hand before parting.—Yours ever,

John Tyndall.

To Mrs. Maxwell.

20th March 1871.

There are two parties about the professorship. One wants popular lectures, and the other cares more for experimental work. I think there should be a gradation—popular lectures and rough experiments for the masses; real experiments for real students; and laborious experiments for first-rate men like Trotter and Stuart and Strutt.

From C. J. Monro, Esq.

Hadley, 21st March 1871.

... I never observed before that ancient colour-nomenclature was more discriminate than ours for the more “violently” refracted tints as compared with the less; but I think there must be something in it. But I have always suspected that they referred colour to a positively distinct set of co-ordinates from ours. Gladstone says something of this sort in Homer; who put it into his head I can’t think; if he made it out for himself I should be very sorry to agree with a man who does not believe in spectrum analysis, and does believe that Leto is the Virgin Mary. Such queer applications of words of colour one does find. You know the “pale” horse of the Apocalypse (vi. 8); well, that is chi lamda omega rho o ́ s which is usually “green,” you know. General Daumas says the Arabs call “vert” what the French call “louvet” in horses; and louvet, in Littré, “Se dit, chez le cheval, d’une robe caractérisé par la présence de la nuance jaune et du noir, qui lui donne une certaine ressemblance avec le poil du loup.... Substantivement,” he continues, “Le louvet n’est, à proprement parler, qu’un isabelle charbonné.” The Arabic for green, and (I have no doubt) the word Daumas speaks of, is akhdár, kh as ch in Scotch, and the dot marking a modification which, it happens, is imitated by interpolating an L in Spanish and Portuguese; so chi lamda omega rho normal o prime final sigma may have been supposed to have something to do with the Semitic word. However, according to dictionaries, “the three greens” in Arabic are “gold, wine, and meat,” which beats the green horse. I suppose the Revisionists will leave “pale,” and certainly chi lamda omega rho normal modifying above o with grave nu δέος? is the Homeric for a blue funk. But chi lamda omega rho normal o prime final sigma, and akhdár, too, are certainly the colour of chlorophyll, and Daumas’s remark is a note on a line in a translation from a poet, which runs “Ces chevaux verts comme le roseau qui croit au bord des fleuves.”

I am glad you are going to preach, and I should like to sit under you, but as you assume, it would not do. Thanks all the same.

To Mrs. Maxwell.

Athenæum, 22d March 1871.

I also got a first-rate letter from Monro about colour, and the Arab words for it (I suppose he studied them in Algeria). They call horses of a smutty yellow colour “green.” The “pale” horse in Revelation is generally transcribed green elsewhere, the word being applied to grass, etc. But the three green things in the Arabic dictionary are “gold, wine, and meat,” which is a very hard saying.

From C. J. Monro, Esq.

Hadley, Barnet, 10th September 1871.

... Of your own things, the Classification of Quantities and the Hills and Dales, are all I have read to much purpose. Nor them either, you may say, if I go on to ask why you say that “in the pure theory of surfaces there is no method of determining a line of water-shed or water-course, except as therein is excepted, that is in page 6? Why does not this determine them? to wit— left parenthesis StartFraction d z Over d x EndFraction right parenthesis squared plus left parenthesis StartFraction d z Over d y EndFraction right parenthesis squared maximum comma ampersand StartLayout Enlarged left brace 1st Row z max for a shed period 2nd Row z min period for a course period EndLayout Or if this does determine them, how does it resolve itself into “first finding,” etc.?

I am glad you like Strutt on sky-blue. You see he sees his way now to a new theory of double refraction. Looking at your old letter again, I don’t quite see the force of either of your objections to space of more than three dimensions. First, you ask if we can think some of the dimensions and not others, then which? Surely one might answer, that depends—depends namely on your circumstances—on circumstances which in your circumstances you cannot expect to judge of.

“I can easily believe,” as Darwin would say, that before we were tidal ascidians we were a slimy sheet of cells floating on the surface of the sea. Well, in those days, the missing dimension, and the two forthcoming ones respectively, kept changing with the rotation of the earth,—we now know how, but could not guess then. So, now, the missing dimension or dimensions, if any, might be determined by circumstances which we could not tell unless we knew all about the said dimension or dimensions.

To Professor Lewis Campbell.

Glenlair, Dalbeattie, 19th October 1872.

... Lectures begin 24th. Laboratory rising, I hear, but I have no place to erect my chair, but move about like the cuckoo, depositing my notions in the chemical lecture-room 1st term; in the Botanical in Lent, and in Comparative Anatomy in Easter.

I am continually engaged in stirring up the Clarendon Press, but they have been tolerably regular for two months. I find nine sheets in thirteen weeks is their average. Tait gives me great help in detecting absurdities. I am getting converted to Quaternions, and have put some in my book, in a heretical form, however, for as the Greek alphabet was used up, I have used German capitals from German upper A to German upper J to stand for Vectors, and, of course, nabla occurs continually. This letter is called “Nabla,”[229] and the investigation a Nablody. You will be glad to hear that the theory of gases is being experimented on by Profs. Loschmidt and Stefan of Vienna, and that the conductivity of air and hydrogen are within 2 per cent of the value calculated from my experiments on friction of gases, though the diffusion of one gas into another is “in erglanzender ubereinstimmung mit StartFraction d p Over d t EndFraction schen Theorie.”

To Professor W. G. Adams.

Natural Science Tripos,
3d December 1873.

I got Professor Guthrie’s circular some time ago. I do not approve of the plan of a physical society considered as an instrument for the improvement of natural knowledge. If it is to publish papers on physical subjects which would not find their place in the transactions of existing societies, or in scientific journals, I think the progress towards dissolution will be very rapid. But if there is sufficient liveliness and leisure among persons interested in experiments to maintain a series of stated meetings to show experiments, and talk about them as some of the Ray Club do here, then I wish them all joy; only the manners and customs of London, and the distances at which people live from any convenient centre, are very much against the vitality of such sociability.

To make the meeting a dinner supplies that solid ground to which the formers of societies must trust if they would build for aye. A dinner has the advantage over mere scientific communications, that it can always be had when certain conditions are satisfied, and that no one can doubt its existence. On the other hand, it completely excludes any scientific matter which cannot be expressed in the form of conversation with your two chance neighbours, or else by a formal speech on your legs; and during its whole continuance it reduces the Society to the form of a closed curve, the elements of which are incapable of changing their relative position.

For the evolution of science by societies the main requisite is the perfect freedom of communication between each member and any one of the others who may act as a reagent.

The gaseous condition is exemplified in the soiree, where the members rush about confusedly, and the only communication is during a collision, which in some instances may be prolonged by button-holing.

The opposite condition, the crystalline, is shown in the lecture, where the members sit in rows, while science flows in an uninterrupted stream from a source which we take as the origin. This is radiation of science.

Conduction takes place along the series of members seated round a dinner table, and fixed there for several hours, with flowers in the middle to prevent any cross currents.

The condition most favourable to life is an intermediate plastic or colloidal condition, where the order of business is (1) Greetings and confused talk; (2) A short communication from one who has something to say and to show; (3) Remarks on the communication addressed to the Chair, introducing matters irrelevant to the communication but interesting to the members; (4) This lets each member see who is interested in his special hobby, and who is likely to help him; and’ leads to (5) Confused conversation and examination of objects on the table.

I have not indicated how this programme is to be combined with eating. It is more easily carried out in a small town than in London, and more easily in Faraday’s young days (see his life by B. Jones) than now. It might answer in some London district where there happen to be several clubbable senior men who could attract the juniors from a distance.

To Professor Lewis Campbell.

Glenlair, Dalbeattie, 3d April 1873.

The roof of the Devonshire Laboratory is being put on, and we hope to have some floors in by May, and the contractors cleared out by October. We are busy electing School Boards here. The religious difficulty is unknown here. The chief party is that which insists on keeping down the rates; no other platform will do. All candidates must show the retrenchment ticket.

The Cambridge Philosophical Society have been entertained by Mr. Paley on Solar Myths, Odusseus as the Setting Sun, etc. Your Trachiniæ is rather in that style, but I think Middlemarch is not a mere unconscious myth, as the Odyssey was to its author, but an elaborately conscious one, in which all the characters are intended to be astronomical or meteorological.

Rosamond is evidently the Dawn. By her fascinations she draws up into her embrace the rising sun, represented as the Healer from one point of view, and the Opener of Mysteries from another; his name, Lyd Gate, being compounded of two nouns, both of which signify something which opens, as the eye-lids of the morn, and the gates of day. But as the sun-god ascends, the same clouds which emblazoned his rising, absorb all his beams, and put a stop to the early promise of enlightenment, so that he, the ascending sun, disappears from the heavens. But the Rosa Munda of the dawn (see Vision of Sin) reappears as the Rosa Mundi in the evening, along with her daughters ♀ and ☿, in the chariot of the setting sun, who is also a healer, but not an enlightener.

Dorothea, on the other hand, the goddess of gifts, represents the other half of the revolution. She is at first attracted by and united to the fading glories of the days that are no more, but after passing, as the title of the last book expressly tells us, “from sunset to sunrise,” we find her in union with the pioneer of the coming age, the editor.

Her sister Celia, the Hollow One, represents the vault of the midnight sky, and the nothingness of things.

There is no need to refer to Nicolas Bulstrode, who evidently represents the Mithraic mystery, or to the kindly family of Garth, representing the work of nature under the rays of the sun, or to the various clergymen and doctors, who are all planets. The whole thing is, and is intended to be, a solar myth from beginning to end.

To Mrs. Maxwell.

December 1873.

I am always with you in spirit, but there is One who is nearer to you and to me than we ever can be to each other, and it is only through Him and in Him that we can ever really get to know each other. Let us try to realise the great mystery in Ephesians V., and then we shall be in our right position with respect to the world outside, the men and women whom Christ came to save from their sins.

To Professor Lewis Campbell.

11 Scroope Terrace,
Cambridge, 26th February 1874.

Jackson has sent me a MS. of yours about the mechanism of the heavens.[230] After the interpretation of είλλομένην, about which Greek appears to meet Greek as to whether it expresses motion or only configuration, the main point seems to be, What is the motion and function of τὸν διὰ παντὸς πόλον?

(alpha) Is it in one piece with the sphere of the stars? or (beta) with that of the sun or (gamma) is it fixed in the earth?

It is evidently a good stout axle, not a mere geometrical line, and it has some stiff work to do.

What is this work?

If the earth is fixed, and the great shafts has its bearings in a hole in the earth, then she (the earth) may, in virtue of her dignity and office, cause the axle to revolve, carrying with it the stars according to alpha, or the sun according to beta. Thus the earth may be the cause of the motion of the Same without moving herself, as a spinster is the cause of the whirling of the spindle, though she does not herself pirouette.

Or we may suppose the earth to act as one who twirls an expanded umbrella over his head about its stick as an axis, the holes in the same representing the stars. The objection to this view (which seems to me to be Jowett’s) is that in stating the relation between the earth and the axis, the earth is said to be related to the axis (packed or whirling as the case may be), and not the axis to the earth. Now, I suppose that without all contradiction the less is related to the better. Here the earth is like a ball of clay packed round a graft on the branch of a tree, rather than like a field in which, by means of a rotatory boring tool, men bore for water.

But the business of the earth is not so much to keep the stars in motion as to effect the changes of night and day. This she may do either by rotating herself from W. to E., or by controlling the motion of the sun, by the help of the great shaft.

Now, if you always observe at the same time of night (a common practice), you find the eastern stars higher every day, and the western lower. All have the same motion, which carries them round from E. to W. in a year.

Mars, Jupiter, and Saturn, in spite of their wanderings go on the whole in the same direction, but slower. Venus and Mercury oscillate about the sun, and the moon goes the opposite way—from W. to E.

That this way of viewing the matter was really prevalent at one time is plain, from the expression the rising of such a star to denote not a time of night but a time of year. It means either (1) the day when the star rises, just before it is lost in the brightness of the sun who follows it, or (2) the day when the star is rising, when it just becomes visible after sunset.

Virgil, who speaks of stars rising, evidently had no practical knowledge of what he meant. Plato, if he sometimes gets hazy, is far clearer than Virgil. Grote would place him far below Mr. Jellinger Symons, who denied the rotation of the moon, because Grote makes Plato say that both the heavens and the earth rotate both in the same direction, and with the same angular velocity.

I think I understand you to make Plato make the earth sit still and preside over the heavenly motions, and so become the artificer of day and night, like a policeman who swings his bull’s-eye round to his back. But his words are capable of being used by the movers of the earth, as Milton says,

I hope you will let me know whether I have not misunderstood both you, Plato, and the Truth. I have never thanked you for your Œdipus, etc., which I have enjoyed. But at present I am all day at the Laboratory, which is emerging from chaos, but is not yet cleared of gas-men, who are the laziest and most permanent of all the gods who have been hatched under heaven.[231]

Mrs. Maxwell joins me in kind regards to Mrs. Campbell and yourself.—Your afft. friend.

To W. Garnett, Esq.

Glenlair, 8th July 1874.

... In the MS. he [Cavendish] appears to be familiar with the theory of divided currents, and also of conductors in series, but some reference to his printed paper [on the Torpedo] is required to throw light on what he says. He made a most extensive series of experiments on the conductivity of saline solutions in tubes compared with wires of different metals, and it seems as if more marks were wanted for him if he cut out G. S. Ohm long before constant currents were invented. His measurements of capacity will give us some work at the Cavendish Lab., before we work up to the point where he left it. His only defect is not having Thomson’s electrometer. He found out inductive capacity of glass, resin, wax, etc.

To Professor Lewis Campbell.

Glenlair, Dalbeattie, 26th September 1874.

Yours of the 29th instant is to hand. Whether your devotion to Michael Angelo has urged you to anticipate his day, or whether Time gallops with those who sit to view Necessity, with her weary pund o’ tow massed round her rock, being all the remains of the stane o’ lint with which she was originally endowed, those who may be set to construe this sentence will be apt to lose much time.

With regard to atoms, I am preparing a hash of them for Baynes of the Britannica. The easiest way of showing what atoms can’t do is to get some sort of notion of what they can do. If atoms are finite in number, each of them being of a certain weight, then it becomes impossible that the germ from which a man is developed should contain (actually, of course, not potentially, for potentiality is nonsense in materialism unless it is expressed as configuration and motion) gemmules of everything which the man is to inherit, and by which he is differentiated from other animals and men,—his father’s temper, his mother’s memory, his grand-father’s way of blowing his nose, his arboreal ancestor’s arrangement of hair on his arms, and his more remote littoral ancestor’s devotion to the tide-swaying moon. Francis Galton, whose mission it seems to be to ride other men’s hobbies to death, has invented the felicitous expression “structureless germs.” Now, if a germ, or anything else, contains in itself a power of development into some distinct thing, and if this power is purely physical, arising from the configuration and motion of parts of the germ, it is nonsense to call it structureless because the microscope does not show the structure; the germ of a rat must contain more separable parts and organs than there are drops in the sea. But if we are sure that there are not more than a few million molecules in it, each molecule being composed of component molecules, identical with those of carbon, oxygen, nitrogen, hydrogen, etc., there is no room left for the sort of structure which is required for pangenesis on purely physical principles. Again, suppose that a great many individual atoms take part in a disturbance in my brain, to whom does this signify anything? As for the atoms, they have been in far worse rows before they became naturalised in my brain, but they forget the days before, etc.[232] At any rate the atoms are a very tough lot, and can stand a great deal of knocking about, and it is strange to find a number of them combining to form a man of feeling.

In your letter you apply the word imponderable to a molecule. Don’t do that again. It may also be worth knowing that the æther cannot be molecular. If it were, it would be a gas, and a pint of it would have the same properties as regards heat, etc., as a pint of air, except that it would not be so heavy.

Under what form (right or light) can an atom be imagined? Bezonian! speak or die! Now I must go to post with two dogs in the rain.—Your afft. friend.

To the Same.

11 Scroope Terrace,
Cambridge, 4th March 1876.

Aias arrived here about a week ago. I read him with pleasure. He recalled the year 1851, when I got him up. The outline of the play seems very bare and unpromising compared with some others, but this is relieved by other features which are not in the “argument,” as e.g. the loyalty of the chorus and of Tecmessa to Aias under all circumstances (for the chorus in general veers about, and backs occasionally, according as the wind blows or the cat jumps).

This contrasts favourably with the character of Athena, who is but so, only not so comic as the Atreidæ.

But why do Ulysses and Aias not name each other in the same language? I suppose the last syllable of Odysseus, pronounced Anglicé, is somewhat unpleasant in verse, and Ajax, though familiarised by Pope, has lost the interjectional sound of your hero’s name.

Two Aberdonians, Chrystal and Mollison, are working at the Cavendish Laboratory. I think Chrystal’s work is of a kind not comparable with that done in “a third-class German university,” which was the charitable hope of Nature as to what we might aspire to in ten years' time. He has worked steadily at the testing of Ohm's Law since October, and Ohm has come out triumphant, though in some experiments the wire was kept bright red-hot by the current.—Your afft. friend.

From the Right Rev. C. J. Ellicott, D.D., Lord Bishop of Gloucester and Bristol.

Palace, Gloucester, 21st Nov. 1876.

My dear Sir—Will you kindly pardon a great liberty? I have quoted in a forthcoming charge a remarkable expression of yours that atoms are “manufactured articles.” Could you in your kindness give me the proper title and reference to the paper and the page? I am now, alas, far from libraries, and have, in matters scientific especially, to ask the aid of others. Will you excuse me asking this further question?

Are you, as a scientific man, able to accept the statement that is often made on the theological side, viz. that the creation of the sun posterior to fight involves no serious difficulty,—the creation of light being the establishment of the primal vibrations, generally; the creation of the sun, the primal formation of an origin, whence vibrations would be propagated earthward?

My own mind,—far from a scientific one,—is not clear on this point. I surmise, then, that the scientific mind might not only not be clear as to the explanation, but equitably bound to say that it was no explanation at all. Excuse the trouble I am giving you, for the truth’s sake, and believe me, very faithfully yours,

C. J. Gloucester and Bristol.

11 Scroope Terrace, Cambridge,
Nov. 1876.

My Lord Bishop—The comparison of atoms or of molecules to “manufactured articles,” was originally made by Sir J. F. D. Herschel in his “Preliminary Discourse on the Study of Natural Philosophy,” Art. 28, p. 38 (ed. 1851, Longmans).

I send you by book post several papers in which I have directed attention to certain kinds of equality among all molecules of the same substance, and to the bearing of this fact on speculations as to their origin.

The comparison to “manufactured articles” was criticised (I think in a letter to Nature) by Mr. C. J. Monro [Nature, X. 481, 15th October 1874], and the latter part of the Encyc. Brit., Article “Atom,” is intended to meet this criticism, which points out that in some cases the uniformity among manufactured articles is evidence of want of power in the manufacturer to adapt each article to its special use.

What I thought of was not so much that uniformity of result which is due to uniformity in the process of formation, as a uniformity intended and accomplished by the same wisdom and power of which uniformity, accuracy, symmetry, consistency, and continuity of plan are as important attributes as the contrivance of the special utility of each individual thing.

With respect to your second question, there is a statement printed in most commentaries that the fact of light being created before the sun is in striking agreement with the last results of science (I quote from memory).

I have often wished to ascertain the date of the original appearance of this statement, as this would be the only way of finding what “last result of science” it referred to. It is certainly older than the time when any notions of the undulatory theory became prevalent among men of science or commentators.

If it were necessary to provide an interpretation of the text in accordance with the science of 1876 (which may not agree with that of 1896), it would be very tempting to say that the light of the first day means the all-embracing æther, the vehicle of radiation, and not actual light, whether from the sun or from any other source. But I cannot suppose that this was the very idea meant to be conveyed by the original author of the book to those for whom he was writing. He tells us of a previous darkness. Both light and darkness imply a being who can see if there is light, but not if it is dark, and the words are always understood so. That light and darkness are terms relative to the creature only is recognised in Ps. CXXXIX. 12.

As a mere matter of conjectural cosmogony, however, we naturally suppose those things most primeval which we find least subject to change.

Now the æther or material substance which fills all the interspace between world and world, without a gap or flaw of StartFraction 1 Over 100000 EndFraction anywhere, and which probably penetrates through all grosser matters, is the largest, most uniform and apparently most permanent object we know, and we are therefore inclined to suppose that it existed before the formation of the systems of gross matter which now exist within it, just as we suppose the sea older than the individual fishes in it.

But I should be very sorry if an interpretation founded on almost conjectural scientific hypothesis were to get fastened to the text in Genesis, even if by so doing it got rid of the old statement of the commentators which has long ceased to be intelligible. The rate of change of scientific hypothesis is naturally much more rapid than that of Biblical interpretations, so that if an interpretation is founded on such an hypothesis, it may help to keep the hypothesis above ground long after it ought to be buried and forgotten.

At the same time I think that each individual man should do all he can to impress his own mind with the extent, the order, and the unity of the universe, and should carry these ideas with him as he reads such passages as the 1st Chap, of the Ep. to Colossians (see Lightfoot on Colossians, p. 182), just as enlarged conceptions of the extent and unity of the world of life may be of service to us in reading Psalm viii.; Heb. II. 6, etc. Believe me, yours faithfully,

J. Clerk Maxwell.

From the Bishop of Gloucester and Bristol.

Palace, Gloucester,
24th Nov. 1876.

Dear Professor Clerk Maxwell—Allow me not to lose a post in thanking you most warmly for your most kind letter and for the packet of pamphlets,—for which I hardly know how enough to express my gratitude. They are exactly what I needed,—yet I fear I may be taking from your stock more than I ought to take. I have already read a good deal of the Encyc. Brit. article on atoms; so pray, if you are short of copies, don’t hesitate to drop me a line. The paper on attraction was also most welcome. I am ashamed to own (for bishops should not enter into these pleasures) that I have of late been speculating a good deal on the physical explanation of gravitation. I seem to feel it must be in the Ether,—and yet how, I see not. In the case of a body near the earth, I can conceive a vast amount of elastic ether behind it, and possibly urging it on, while a small quantity is under it, being excluded by the earth.

I seem also to see how this might be applied to the case of the heavy bodies that fell nearer to the steep side of Schehallion than they ought to have done by calculation; but then, when I attempt to go farther, I find the theory break down.

It seems to me that we want for several things, e.g. light, the conception of an ether-beach all round the visible universe from which waves might be reflexively started, and at which the particles might be more closely packed; but then again I see not what it is that keeps up the beach.

But I am really ashamed of troubling you, a scientific man, with such wanderings. It will only show that your kindness is thoroughly appreciated.

I cordially agree with you as to the light question. Theologians are a great deal too fond of using up the last scientific hypothesis they can get hold of. The Christian Knowledge Society are publishing my charge. When it is published I shall ask you to do me the favour to accept a copy. You will then see that the best note in the little volume is due to your kindness and aid. I remain, with all good wishes, and sincere thanks, very faithfully yours,

C. J. Gloucester and Bristol.

(P.S.)—If you are in London in the spring and near the Athenæum, do me the kindness of looking in on me, as I shall be very glad to make your personal acquaintance. I am commonly in town regularly after Easter.

To Professor Lewis Campbell.

Glenlair, Dalbeattie, Christmas 1876.

... I hope that when this severe weather is past you will be able to derive benefit from a moderate use of Plato and Sophocles.

We intended to have gone round by Edinburgh, to pay Aunt Jane a visit; but we both had such bad colds that we came home to nurse them, and are now snowed up, and enjoying the artificial heat of coals, peats, and sticks judiciously intermingled.

The demonstrator at the Cavendish Laboratory has been out of sorts all this term, and has had to go home about a month ago, so we have not been in full force there. I hope he will be well in February, to absorb the energy of the new B.A.’s set free from the Tripos and its attendant anxieties.

As we get richer in apparatus, mathematical lectures give way to experimental, and the black board to the lamp and scale. I have had a pupil quite innocent of mathematics who has learned to measure focal lengths of lenses, and has found the electro-motive force from the water-pipes to the gas-pipes, and from either set of pipes to the lightning-conductor.

I have been making a mechanical model of an induction coil, in which the primary and secondary currents are represented by the motion of wheels, and in which I can symbolise all the effects of putting in more or less of the iron core, or more or less resistance and Leyden jars in either circuit.

I have also been making a clay model of Prof. W. Gibb’s thermodynamic surface, representing the relations of the solid liquid and gaseous states, and the different paths by which a body may get from the one to the other.—Your afft. friend,

J. Clerk Maxwell.

To W. Garnett, Esq.[233]

Glenlair, 4th January 1877.

By all means take the Groves and coils for your lecture. Are you aware that the electric flash is entirely due to the resinous particles of electricity? This is well known on the stage, where they blow the particles through a tube over a candle to make stage lightning. The vitreous electricity has nothing to do with it, as you may prove by using pounded glass.

I think it a pity that the old historical word Dynamics should, for mere considerations of time, be split up into Kinematics, Kinetics, and Statics. With respect to the divisions of the subject, I think they fall thus:—

1. Early attempts at founding the science, ancient Kinematics (mechanical description of curves, etc.) generally correct.

Ancient Statics.—Archimedes.

Modern Dynamics.—Galileo, first founder. Descartes, good up to Kinematics and Statics, failed in Kinetics.

Promoters—

Wren, Wallis, Huygens, Hooke.

Laws of collision established, and motion in a circle.

Newton.

Three laws of motion. Form suggested by the laws of Descartes. Meaning established by Newton’s own copious and complete examples of using them.

Second statement of Newton’s third Law.

My notions on the three laws are in “Matter and Motion.”