Thomas Rawson Birks to Faraday   24 August 1855¹

Dear Sir

Though I am personally a stranger to you, I venture to hope that you will forgive me for intruding upon your time by a few lines of inquiry, as my only object is to advance the science, to which you have contributed so many important discoveries.

I have now at intervals for nearly twenty years since my residence at Cambridge had an idea in my thoughts, which I conceive may furnish a key to unite several branches of physical science, & throw a fresh light on chemical & electrical science. I have just of late been using some intervals of leisure from other duties in unfolding it to myself more clearly, with some view to publication. It is one part of the theory that all chemical elements are really compounds of the first order, & that all their properties flow by mechanical laws originally from their atomic numbers & electric order. But this part of the theory is not ripe enough at present to trouble you with reference to it. My inquiry relates to the theory of electricity alone.

You are well aware that the theory of Poisson, simplified by Dr Whewell in the Enc. Metr.² explains all these phenomena by two electric fluids. From Delarive’s work I infer that you incline to reject these fluids entirely³, & to explain the chief phenomena by simple induction only. My own theory wd lead me to an intermediate view, that there is no distinct electric fluid, but that it depends on the increase or diminution of ethereal electricity at the surface of charged bodies. This wd differ from your view, if I am right in my impression, because yours wd exclude all action in vacuo; & from that of Coulomb & Poisson, because the influence, on their hypothesis, depends on distance only, & in mine, on inclination also.

Now I venture to trouble with the inquiry whether an experiment of this nature has been ever tried which wd, I think, decide between their view, & the modified one in question. Let two charged square discs, moveable on their centres, be placed opposite & near each other, & their repulsion carefully measured. Let them next be inclined on their axes to each other, say at an <angle> of 30˚[.] On the hypothesis of two fluids, & non conducting surfaces, the repulsion shd be increased, since the nearness of the upper halves will more than compensate for the recession of the lower halves. But if the action depends, as I conceive, on the size of the inclination, the force wd be diminished to nearly one half. Now I wish, if it be not troubling you too much, to inquire, whether such an experiment has been made by Sir Snow Harris or yourself, & with what result, of if not, whether you think it wd be worth the trial. Hoping you will excuse the liberty I have taken, I remain, with most sincere respect & esteem

Yours very truly | T.R. Birks | Late Fellow of Trin Coll. | Camb

Kelshall Rectory | Royston | Augt 24th 1855