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 196 Faraday. we can picture this vector as being of the nature of a displacement. By such an assumption we should avoid altogether the necessity for regarding the conduction-current as an actual flow of electric charges, or for speculating whether the drifting charges are positive or negative; and there would be no longer anything surprising in the production of a null effect by the coalescence of electric charges of opposite signs.

Faraday himself wished to leave the matter open, and to avoid any definite assumption. Perhaps the best indication of his views is afforded by a laboratory note of date 1837:—

"After much consideration of the manner in which the electric forces are arranged in the various phenomena generally I have come to certain conclusions which I will endeavour to note down without committing myself to any opinion as to the cause of electricity, i.e., as to the nature of the power. If electricity exist independently of matter, then I think that the hypothesis of one fluid will not stand against that of two fluids. There are, I think, evidently what I may call two elements of power, of equal force and acting toward each other. But these powers may be distinguished only by direction, and may be no more separate than the north and south forces in the elements of a magnetic needle. They may be the polar points of the forces originally placed in the particles of matter."

It may be remarked that since the rise of the mathematical theory of electrostatics, the controversy between the supporters of the one-fluid and the two-fluid theories had become manifestly barren. The analytical equations, in which interest was now largely centred, could be interpreted equally well on either hypothesis; and there seemed to be little prospect of discriminating between them by any new experimental discovery. But a problem does not lose its fascination