Royal Institution | 23 Feby. 1855
My dear Dr. Whewell
Your letter2 was very acceptable to me for it gives me courage, and I am heartily thankful to you for it. I have given many figures of lines of force at different times, and briefly refer you to them. Thus in the Paper on Magnetic conduction (2797)3 there are figures at 2807. 2821. 2831. 2874. 28774. 2972. 29935. The paper on lines of Magnetic force (3099)6 has a plate full of figures in reference to their delineation (3234)7 drawn from nature; and the paper on Physical lines (3243)8 also has a plate. Still I think that, as you suggest, figures more numerous still would be very useful. I have, however, been in some degree deterred from pressing these matters too hard, because I wanted to see how far that which has been advanced might be accepted or justified; and also because I wanted to trace more clearly to myself the origination & development of the lines of force round a wire carrying a current; through & about a helix - without or with an iron core; and amongst wires & helices in juxtaposition. Above all I want to obtain some clear idea of the coercitive force, & how it is that an electro helix, having but weak powers itself as a magnet, can raise up (or arrange) such a powerful system of lines when an iron core is introduced. I have other matters too in hand, regarding magnecrystallic action, which I hope to develop soon & think may turn out well. Your recommendation, however, shall not be forgotten & I shall probably soon begin to collect cases for illustration.
I conclude I am right in believing that if diamagnets & diamagnetism had been known to us before we knew any thing at all of Paramagnets & paramagnetism, the theory of two magnetic fluids would have applied to it, but could not then have included paramagnetism. It is this idea which makes me earnest in speaking of chambers of little or no action & places of weak magnetic action; for though the old theory of two fluids can account for them, they are not the less important to me who do not believe in that theory. I see in them proofs that the dualities must be related externally to the magnet; & so they come in as necessary consequences of the principles both of paramagnetic & diamagnetic action; but I hope to make all this clearer by degrees; & my hopes are greatly strengthened by the growing admission that the lines of magnetic force represent at present fairly the facts of magnetism. Into what they may ultimately resolve themselves, or to what they may lead I am sure I cannot say; but if I can only convert the theory of magnetic fluids, & that of electric currents, into two stools, the fall to the ground between them may be more useful than either of them as a seat in a wrong place.
I am | My dear Dr. Whewell | Yours faithfully | M Faraday
FARADAY, Michael (1851d): “Experimental Researches in Electricity. - Twenty-sixth Series. Magnetic conducting power. Atmospheric magnetism”, Phil. Trans., 141: 29-84.
FARADAY, Michael (1851e): “Experimental Researches in Electricity. - Twenty-seventh Series. On Atmospheric magnetism - continued”, Phil. Trans., 141: 85-122.
FARADAY, Michael (1852b): “Experimental Researches in Electricity. - Twenty-eighth Series. On Lines of Magnetic Force; their definite character; and their distribution within a Magnet and through Space”, Phil. Trans., 142: 25-56.
FARADAY, Michael (1852c): “Experimental Researches in Electricity. - Twenty-ninth Series. On the employment of the Induced Magneto-electric Current as a test and measure of Magnetic Forces”, Phil. Trans., 142: 137-59.
FARADAY, Michael (1852d): “On the Physical Character of the Lines of Magnetic Force”, Phil. Mag., 3: 401-28.
Please cite as “Faraday2942,” in Ɛpsilon: The Michael Faraday Collection accessed on 29 April 2024, https://epsilon.ac.uk/view/faraday/letters/Faraday2942