64 W. A. Norton on Molecular Physics. 
should therefore be in excess upon the outer sides of the wires; } 
and hence they should be urged toward each other, or there _ 
should be an apparent attraction between the wires conveying 
the currents. The excess of ethereal tension here alluded to is 
attributable to the fact that the impulses proceeding from the 
one wire, in being propagated through the other, are materially 
reduced in intensity. ‘This effect results mainly from the disper- 
sion produced by the interstitial ether, which is brought into a 
very disturbed state of density by the swiftly moving atoms of 
the electric ether in the current. en only one of the wires 
conveys a current, no attraction or repulsion is observed, be- 
eause the dispersion just mentioned is wanting. t 
If the currents be supposed to traverse the wires in opposite —_ 
directions, then the same operative cause, the external impulsive 
forces of the currents, will compress the ether between the wires 
to a greater degree than beyond them, and thus there will be an 
effective force urging them farther apart. 
t a, fig. 8, be a point of one of the currents, from which an 
impulse is propagated, and ab, ac, ad, 
lines radiating from it and crossing the 
moving electrical atoms. Each of the {_ ”~ sail 
- Jines ab, ac, ud, willcross the same num- ~ 
ber of such lines, and therefore impulses propagated along them 
will encounter the same number of moving atoms, and experi- 
ence the same proportional diminution. This diminution should 
of the propagated impulse, in traversing the wire, simply by 
of the increased length of the passage, as the line is more 
oblique, should also be a constant fractional part of the impulse; 
since fc is the same proportional part of af, or an for each point 
of the wire. Hence the action of any point a of the first wire, 
upon any point f of the second, should be inversely proportional 
to the square of the distance; and the entire force of action of 
one indefinite wire upon another should be inversely propor- 
tional to the distance between the two. (See Lamé, Cours de 
Physique, vol. ili, p. 236.) 
If the currents cross each other under a certain angle instead 
of being parallel, it may be seen by attending to the mutual 
actions of the separate points of the two currents, that there 
will be attractions or repulsions according to the relative direc: 
tions of the currents at the points; and that the entire action 
will tend to bring the two currents into the same direction, in 
which the attraction will bea maximum. ~ 
