Faraday to Alexander John Gaspard Marcet   15 January 1822

Royal Institution | Tuesday Jany 15th 1822.

Sir

I am very much obliged indeed by your kindness in permitting me a perusal of M Berzelius’ letter and hasten to return it to you with many thanks¹. It does not contain many of M Berzelius’ own ideas of electromagnetism but consists rather of observations on M. Ampere’s theory. I cannot gather from it whether M Berzelius retains the same opinion that he gave in his letter to M Berthollet² and which was published in the Annales de Chimie³[.] He still speaks of an alternation of poles and refers to the number he formerly gave of two pair but does not say that they are sufficient to explain the phenomena. It appears to me that no succession of poles round the wire however numerous will account for the phenomena indeed the fact of rotation is decidely [sic] against such a supposition: but even the phenomena mentioned by Oersted cannot be explained by it for take any particular point on the surface of the wire however small and it may be made apparently either to attract or repell either one pole or the other of a magnetic needle merely by changing the position of the needle to the wire[.]

With regard to the theory of M Ampere it is but justice to that philosopher to say that M Berzelius does not seem to have an exact conception of it or at least of the position of the currents which it supposes. In the diagram of the earth M Berzelius has assumed one small current in the plane of the magnetic equator[.] M Ampere assumes a current or currents parallel to the equator but not I believe confined to it[.] If I understand him right he assumes many currents in various directions but the general tendency is to a direction round the earth & parallel to the equator a supposition which admits of having terrestrial currents even up to the pole & yet parallel to the equator - In the Magnet M Ampere has not yet decided whether he shall put the currents concentric to each other and having the axis of the magnet for their axis or whether they shall be placed round each atom of matter the axis of all the currents being then however parallel to each other & to the axis of the magnet[.]

All the objections urged by M Berzelius to M Ampere’s theory founded on the difficulty of supposing an electromotive force in steel & nickel or currents in the magnet &c &c &c remain with their full force and though M Ampere seems very well satisfied with his theory in its present state yet certainly much more must be done with it and much more proved by experiment for it before a cautious philosopher will receive it into his stock of knowledge or think it at all approaching to invulnerable.

I am Sir | Your Obliged & faithful Servant | M. Faraday

Dr. Marcet

Address: Dr. A Marcet | 14 Harley Street