488 Mr. Babbage and Mr. Herschel's account of the 
of this action parallel to its surface, would continually urge it 
in the direction of the magnet's motion. 
29. But besides the attracting pole of the opposite name 
(south) produced by the (north) pole of the magnet at the 
spot immediately under it, there will also be developed a 
corresponding repulsion or north polarity in the plate. This 
however will not, like the attractive, be concentrated nearly 
in one spot immediately below the magnet, but must of 
necessity be diffused round it in a much less intense and 
more uniform state throughout the more distant parts of the 
mass, and may be conceived as arranged in spherical or 
other concave strata about the point vertically under the 
magnet as a centre. Now when the magnet by its motion 
is carried out of the axis of these strata, it is obvious that the 
resultant force of each of them will be less and less oblique 
to the surface as its radius is greater. The general resultant 
therefore of all the repulsive forces exerted throughout the 
whole extent of the plate is necessarily less oblique to 
the surface than that of the attractive ones, whose influence, 
from this cause alone, must therefore preponderate, and 
must necessarily produce a dragging or oblique action, such 
as above described. This force, however minute, acting con- 
stantly, must at length produce a finite and sensible velocity, 
provided the whole mass of the plate to be set in motion 
be finite, and the force of the magnet sufficient to overcome ' 
friction, resistance, &c. 
so. Vice versa, if the plate be drawn along in its own 
plane, and the magnet be free to move in a horizontal direc- 
tion, the former ought to drag the latter along in the same 
