PRODUCED BY ALTERNATING ELECTRIC CURRENTS. 
285 
(i.) When 6h is positive and greater than d, both couples are positive. 
Fig. 8. Fig. 9. 
(ii.) When 6h is numerically less than d, the a, h couple is positive and the 
a, b' negative. 
Fig. 10. 
I 
(iii.) When 6h is negative and 
negative. 
Fig. 11. 
numerically greater than d, both 
couples are 
If We place another wire by the side of that already in position, and thus make a 
filament alternately magnetised in a direction perpendicular to its length, and making 
an angle a with OX (as with the cylinder), then the couple on the a, b sphere is 
K" 
? e lTr^'p*a i a! i cro- > 
p^p'" A] A’ 1 # 
[sin 2 (y 
y) 4» 3 sin 2 (& «“ y — y')], 
and on the a, b' sphere 
