great electric movements above the atmosphere, it would be difficult to place these in the category of galvanic currents; for although everything seems to indicate that we should regard galvanic currents as electricity in motion, yet every movement of electricity is not a galvanic current—it is so only when the movement forms a circle returning back into itself. As it is only under this condition that it is allowable to make the often-mentioned substitution of separated magnetic fluids instead of the galvanic current, then, in the hypothesis mentioned, our relations between the components would no longer apply; that is to say, the second case would actually present itself. Even the certain establishment of this important circumstance would be in itself of great interest, and by that time we may hope to possess such extensive and accurate observations as may make it possible to trace both the source and the nature of the causes.
G.
