Voltaic Induction. 43 
these circumstances, I should be led to conclude, that the mass of 
positive and negative currents, generated under the magnet, proceed- 
ed directly towards the opposite points C B, and completed the cir- 
culation, along the same line, upon the opposite side of the plate. 
The supposition, that they form two distinct circles upon the upper 
surface of the plate, one on either side of the magnet, seems, howev- 
er, to be admitted both by Faraday and Nobili. I shall, accordingly 
adopt it, and proceed to illustrate the movements of the magnet. 
Ist. Rotation with the plate.—It will be seen, by reference to the 
2nd fig. at the commencement of this enquiry, that the magnetic force 
which issues from the interzor of a voltaic circuit, gives to that side 
of the circle, its active polarity. This is a general rule; and if we 
examine the voltaic currents upon the revolving plate, (fig. 7.) we 
shall perceive that the one, generated by the particle a, has a north 
pole issuing from the interior, upwards. Hence this voltaic circle, de- 
noted by R, must tend to repel the magnet, whose north pole is 
down ;’ whereas the voltaic circle A, generated in the particle }, hav- 
ing a south pole issuing from its interior, must attract it. As both 
these circles act obliquely upon N, above them, their tendency will 
be to move the magnet horizontally, and in the direction of the re- 
volving plate. 
2nd. Repulsion of the magnet perpendicularly from the plate.— 
In order to explain this fact, I do not consider it necessary to suppose, 
with Faraday, that the currents require a certain portion of time for 
generation ; but simply, that they exist for a short period after their 
creation, which, indeed, seems to follow as a matter of course. Pre- 
suming that such is the fact, it is obvious that, in consequence of the 
motion of the plate being necessarily much greater than that of the 
magnet, the circle of repulsion R, gets under the magnet and forces 
it directly upwards. 
3rd. and 4th. Motion of the magnet towards the circumference and 
centre of the plate.—If, during the revolution of the plate, the mag- 
net be moved along the line C B towards B, the circle of repulsion 
R, by the motion of the plate, gets more or less between the magnet 
and the centre C, and hence repels it towards the circumference of 
the plate :—but, when the magnet is made to approach C, the same 
circle advances so as to pass between it and the circumference, and 
thus compels the magnet to incline towards the centre. __ 
All these movements will, it is hoped, be sufficiently intelligible, by 
a reference to the figure, and the hypothesis is equally applicable, 
