1640.  Having thus removed the difficulty out of the way of my views regarding a current, I did not pursue this curious experiment further.  It is probable, that the difference between my results and those of M. de la Rive may depend upon the relative values of the currents used; for I employed only a weak one resulting from two pairs of plates two inches long and half an inch wide, whilst M. de la Rive used four pairs of plates of sixteen square inches in surface.

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1641.  Electric discharges in the atmosphere in the form of balls of fire have occasionally been described.  Such phenomena appear to me to be incompatible with all that we know of electricity and its modes of discharge.  As time is an element in the effect (1418. 1436.) it is possible perhaps that an electric discharge might really pass as a ball from place to place; but as every thing shows that its velocity must be almost infinite, and the time of its duration exceedingly small, it is impossible that the eye should perceive it as anything else than a line of light.  That phenomena of balls of fire may appear in the atmosphere, I do not mean to deny; but that they have anything to do with the discharge of ordinary electricity, or are at all related to lightning or atmospheric electricity, is much more than doubtful.

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1642.  All these considerations, and many others, help to confirm the conclusion, drawn over and over again, that the current is an indivisible thing; an axis of power, in every part of which both electric forces are present in equal amount[A] (517. 1627.).  With conduction and electrolyzation, and even discharge by spark, such a view will harmonize without hurting any of our preconceived notions; but as relates to convection, a more startling result appears, which must therefore be considered.

[A] I am glad to refer here to the results obtained by Mr. Christie with magneto-electricity, Philosophical Transactions, 1833, p. 113 note.  As regards the current in a wire, they confirm everything that I am contending for.

1643.  If two balls A and B be electrified in opposite states and held within each other’s influence, the moment they move towards each other, a current, or those effects which are understood by the word current, will be produced.  Whether A move towards B, or B move in the opposite direction towards A, a current, and in both cases having the same direction, will result.  If A and B move from each other, then a current in the opposite direction, or equivalent effects, will be produced.

1644.  Or, as charge exists only by induction (1178. 1299.), and a body when electrified is necessarily in relation to other bodies in the opposite state; so, if a ball be electrified positively in the middle of a room and be then moved in any direction, effects will be produced, as current in the same direction (to use the conventional mode of expression) had existed:  or, if the ball be negatively electrified, and then moved, effects as if a current in a direction contrary to that of the motion had been formed, will be produced.