A.B.¹ to Faraday   After 1844

Sir,

I am fully aware that the Vibratory Hypothesis has been frequently alluded to - but only I believe in general terms. Mathematical investigation, is, undoubtedly, the only thoroughly satisfactory one, but in the present state of Mathematics the problem is beyond the power of Analysis: Even in the Undulatory Theory of Optics, mathematicians have only succeeded in giving general explanations; a Dynamical Theory does not as yet exist, altho’ attempts have been & are making by Cauchy² &c. to establish one. Airy’s Tract³, though full of mathl. calculations has only analogies (from sound and the motion of water) in place of direct Mechanical Theory. Having taken a Wrangler’s degree at Cambridge, I have sufficient knowledge of the present state of Analysis to perceive the almost insurmountable obstacles to anything like a general theory founded on purely Dynamical Principles. Moreover even if such existed, the Data are still wanting. We know not the Law of Elasticity in the Ether or in other bodies, &c &c. In such circumstances then, we must be content with such analogies & reasoning, as may suffice for a general comprehension of phenomena which we cannot examine minutely or subject to rigorous calculation. This I have endeavoured to do in a few cases - & so far as regards the ‘action of points’ I conceive that a satisfactory explanation has been offered - where no attempt of the kind has hitherto been made. I am not aware either that any (even general) explanation has been offered of the way in which Heat & Light are produced in Electricity. That one causes the other or is accompanied by it, has been stated often enough, but I believe that is all. More than that - it is only to those who hold the Undulatory Theory of Optics that the production of Light can be intelligible - & to those who assign Heat to the same class of vibratory motion, that the Calorific Effects are intelligible. Now there are hundreds who cling to the old ‘emission’ theory who nevertheless talk about ‘Heat, Light, Electricity’ as having one common origin? They have no right to do so.

I am very far however from being satisfied with the general views (altho’ I cannot but think they are of value, in the absence of anything better) given in my Paper - but intend to obtain, if possible, a mathl. theory. And whereas in the Undulatory theory of Light the Ether is supposed not to be condensed by the motion - in Heat & Electricity I should start with the supposition that there is condensation: & that the motion of the particles is in the direction of propagation, contrary to that which is supposed in the Optical Theory in which the motion of each particle is perpendicular to the dir[ectio]n of propagation. I have troubled you with these remarks, because I do not think that any of those who have referred to this Hypothesis, have attempted to enter into any mechanical details, which, tho’ but to a very small extent, I have done.

Your’s Obediently | A.B.