Problems of Hydrone and Water

Abstract

CLERK MAXWELL used to say that it was a sign of progress when we began to overhaul the foundations of our science and return to the very beginnings. Prof. Armstrong is calling upon us to do this in electricity. All I want to suggest to him at present is that he is rather over-emphasising the rô1e of electrolysis and conduction generally, and not recognising the full value of electric displacement, so much emphasised by Faraday and Maxwell. Conduction necessarily involves some dissipation of energy, something analogous to friction; it does not store energy, and it gives no recoil. A pure dielectric dissipates no energy, and it recoils perfectly. A dielectric slab brought near a charged body becomes polarised, positive on one face, negative on the other: there has been a displacement of electricity through it, but not by conduction. It may even be worth while to ask Prof. Armstrong to refer back to an ancient paper of mine in the Phil. Mag. for November 1876, in which I design models to illustrate Maxwell's theory. This paper, I was delighted to find, pleased Clerk Maxwell sufficiently to induce him to write me a most interesting letter about it—humorously suggesting, I recollect, lubrication with Canada balsam as suitable for § 10 of that paper,—a letter which, to my long-standing regret, has suffered from “moving accidents” and got itself lost. If the elastically supported buttons or beads on the cord of that model slip on the cord, there is conduction; but if they grip it tight, they represent a dielectric.