42 Voltaic Induction. 
particles composing the plate. In consequence of the rotation in the 
direction indicated by the figure, the induction of the particle a, 
will commence upon the surface cut by Na, and next to the line BC, 
whereas the same process will commence, for 6, upon its surface 
most remote from the line BC. As the magnetic forces of the mag- 
net, act in planes perpendicular to the revolving plate, so will the in- 
duced magnetic circles nn’; and the voltaic circuits resulting from 
this rotation, must necessarily coincide with the plane of revolution. 
Both the particles @ and 6, will have a north polar force repelled 
around them, from left to right, wnder, and must aceordingly be pen- 
etrated, at right angles to the rotation, by a positive current moving 
towards the centre C, of the plate. | Now experiment fully indicates 
the existence of such a current, as will be shown presently. These 
positive currents, issuing from the particles, are represented by the 
circular arrows upon each side of the magnet, and it is supposed, 
that being accompanied by a negative current, moving in an opposite 
direction, each one, instead of proceeding in straight lines to the cen- 
tre of the plate, turns outwards, as it advances, in order to meet its neg- 
ative current; and thus the two voltaic circles A, R are formed, upon 
either side of the magnet. As all the magnetic circles arise within 
the limits of the forces projected from the magnet upon the plate, it 
necessarily follows that the strongest currents will be found passing 
under the magnet, in lines more or less parallel to B C, or the radi- 
us which bisects these projections. The galvanometer abundantly 
proves this to be the case, and a few positions of the instrument, 
fully confirm the hypothetical direction, here given, to these cur- 
rents. ‘Thus, when one wire of the galvanometer is placed at C, 
and the other at @ or 6, under the magnet, the latter will be found to 
convey a negative current; but when the wire at C is removed to B, 
near the circumference, that one at 6 or a@ remaining stationary, the 
latter will convey a positive current; consequently, opposite currents 
must issue from beneath the magnet, a negative one moving towards 
B anda positive one towards C. When the same wires were placed, 
one on each side of the radius B C, I could obtain no evidence of a 
circulation, which circumstance seems to indicate, that, in these po- 
sitions, they rest upon two distinct systems of voltaic circulation, A 
and R; and this opinion is confirmed by the additional fact that cur- 
rents enter the galvanometer wires, when both are placed upon the 
same side of the line B C, even though they are removed from each 
other as far as the limits of the plate will permit. Were it not for 
