Benjamin Cheverton to Faraday   21 June 1857

45 St James Sq | Notting Hill | June 21, 1857

Dear Sir,

I return you Mr Maxwell’s paper¹ with many thanks for your kindness in sending it to me. I have been greatly interested in its perusal, so far at least as I could follow it, but I feel somewhat disappointed that the form given to your conceptions, should not have been that of an hypothesis - if even only of a provisional character - and that to serve the purpose better of calculation within a limited degree, it should have been so very arbitrary & artificial, - so much so perhaps, as to exclude it from more general applications than the subject & the simple idea of “lines of force” would of themselves impose. This is not satisfying I should think to a mind like yours, nor probably will it be to the philosophic mind generally, if we may judge from the eagerness with which both the emissive & the undulatory ideas of light, are accepted as theories of what is real. And yet it is very true, perhaps, as Mr Maxwell intimates, that neither each of these should be taken at present for more than analogical mathematical forms of treating the subject, until a course like your own, of interrogating nature herself, shall lead to something determinate²[.]

Probably also, you do not yourself attach to your own “lines of force”, any distinct physical ideas; but are content for the present to adopt them as a method of thought, which enables you with greater freedom & especially with greater generality, to reason concerning phenomena, to form conceptions as to their connections & relations, and so derive hints for further experiments. In truth if matter be only the manifestations of force - of which through a consciousness of the ability to exist it, as well as from feeling it, we know to be something real, and real after the same manner externally as it is sensibly so - I do not see how, in ultimate inquiries any additional physical ideas beyond those of equal external reality, time space & motion, can have any place; inasmuch as any others would be only the affections of percipient beings - psychological effects of force as the cause. So that to be chary of physical ideas, even to the absence of almost every thing from “lines of force”, would be rather to approach than to recede from the truth of nature, what is wanting thereto, is an hypothesis that shall be truthful looking at least, & which shall not merely serve to being the subject under calculation - for Mr Maxwell shows us; that arbitrary conceptions will to a certain extent of application answer that purpose - but which shall unite all phenomena under one comprehensive view. To do that however, I am afraid we have no other means at hand, at present, than the occult qualities (as in a sense they are) of attraction & repulsion; but how to evoke sensible from general attraction, or vice versa, as Mossotti³ proposed to do⁴, is the great difficulty.

This leads me to observe, that the simplicity & paucity of physical ideas to which I have adverted, belong only to an investigation which is in the track of ultimate enquiries. But building on this foundation, complexities will arise, & so introduce other physical conceptions if only from the combinations of the primary ideas, and notwithstanding that we carefully exclude any thing merely of sensational origin, such for instance as may be suggested by a too liberal inference from the electric spark or fire. Now in regard to electricity & magnetism, it may be a question, whether this is not the case with their phenomena - whether they do belong to the ultimates. Am I not right in thinking, that their attractions & repulsions are so dependent on circumstances, - are so variable & conditional in obedience to mere form & to mere extent of surface, as to indicate that they are secondary consequences, & not the result of primary properties, or of primary conditions in the action of force? Now this is not observable in gravitation, where accordingly, we seem to arrive at something that is ultimate, - it not being dependent on physical ideas resulting from secondary combinations but on the mass - simply & entirely on the mass. Therefore I do not see how the form which Mr Maxwell has given to your “lines of force”, can be applied to gravitation - reasoning merely in the manner of calculation - seeing that the action of the imaginary fluid, varies after a manner with the sources & sinks on the surface; whereas gravitation, is proportional to the mass, however contracted or extended may be the surface. I may be wrong - still this application is no where alluded to by him. And yet “lines of force” in some more simple guise, would I conceive apply to gravitation.

Mr Maxwell has not attempted philosophy - indeed he takes care that his physical conceptions shall not by any possibility be mistaken for it. As a mathematician intent only on the means of calculation, this may be very proper, especially if by so doing he secures, as he certainly does, great simplicity in that respect, founded on the Engineer’s method, of taking account of force only in pressure & resistance[.]

As far as in their relations to crystallisation have engaged your attention, I will take this opportunity of stating, what I mentioned many years since at the meeting of the British Association at Dublin⁵ to Dr Robinson⁶, Dr Dalton⁷ & Col Sabine, but which did not seem to attract any attention, except from the last named gentleman, that I have found diamonds in the state of splintered sparks, show signs of attraction, without excitation by heat or any extraneous cause. I have drawn them along, on not a smooth surface, by a piece of brass; & if I recollect aright have seen them suspended from it by their points. As I wanted them for immediate use, I made no other experiments, & can speak to two instances only. Perhaps however others have observed the same thing, but I have never seen it stated.-

I find I have here been led on, into what to you, I feel to be almost unpardonable garrulity. I have only to hope, & beg of you that you will not conceive yourself engaged in courtesy, to lose your valuable time in taking any notice of it.

I remain | Dear Sir | Yours respectfully | Benj Cheverton

Professor Faraday &c