Note 174 — Chapter X

“The foundation of our researches is the assumption that the terrestrial magnetic force is the collective action of all the magnetised particles of the earth’s mass. We represent to ourselves magnetisation as the separation of the magnetic fluids. Admitting the representation, the mode of action of the fluids (repulsion of similar, and attraction of dissimilar, particles inversely as the square of the distance) belongs to the number of established truths. No alteration in the results would be caused by changing this mode of representation for that of Ampère, whereby, instead of magnetic fluids, magnetism is held to consist in constant galvanic currents in the minutest particles of bodies. Nor would it occasion a difference if the terrestrial magnetism were ascribed to a mixed origin, as proceeding partly from the separation of the magnetic fluids in the earth, and partly from galvanic currents, in the same; inasmuch as it is known that for each galvanic current may be substituted such a given distribution of the magnetic fluids in a surface bounded by the current, as would exercise in each point of external space precisely the same magnetic action as would be produced by the galvanic current itself.”—General Theory of Terrestrial Magnetism, by Professor Carl Friedrich Gauss, of the University of Göttingen.—Scientific Memoirs, vol. ii. p. 188.