Faraday to Samuel Alfred Varley   5 March 1859¹

[Royal Institution embossed letterhead] | R Institution | 5 Mar 1859

Dear Sir

I cannot remember the words I used on the occasion referred to² & how much one part was qualified by another but I can tell you what my present thought is[.] That amount of inductive force which is occupied for the time in charging the near part of the wire is taken off so to say from the wire & makes it go slower than if there was no lateral induction. The larger the wire with the same thickness of the surrounding gutta percha the greater the conduction & therefore the reduction of the forward tension[.] But as a large wire facilitates conduction in proportion to its mass whether in air water or gutta percha so a large wire must as respect[s] conduction be better than a small one only respect must be had to the conduction effect. My expectation is that as the induction is as the surface of the wire but the conduction as the square of the surface ie as the mass so the large wire as a whole will have less proportional induction compared to conduction than the small one.

As to giving opinions on or making observations on your paper & the controverted points referred to in it I must decline that being always anxious to avoid controversial matter. You are quite able to hold your own there³[.]

Ever Truly Yours | M. Faraday

S.A. Varley Esq | &c &c &c