(31) 
of the magnetic induction %, both expressed in magnetic units, then 
for a medium that is magnetically anisotropic: 
= Urd + May b + Urze, o « eo « « « (10) 
OS Md EO ye sn on | GD 
YS be @ Uy b + oe y «ee © (12) 
where Moy = (jes xz = Mer, Mie = Hey, … Hence, by solving a, b 
and ¢: 
A= lige U + fligy [2 + Miz Ys 2 « 6 «© (13) 
b= lye @ Huy B+ yey. - « « « © (14) 
CS Mizz a ae Mxy p -|- MV 9° ° ° ° ° (15) 
where guy = yey, Woz = Mary yz = Mey. The magnetic (kinetic) 
energy Um is per unit volume: 
1 
Dis (Gas OP Ae plee a ot el VKO 
8 77 
I call further the ellipsoid: 
fae B® Huy + zee? Huys y2 +2 Mag 20 + 2 Mey ay = 1 
the magnetic ellipsoid, and 
srt? Hy y? Hz 27 HZ lye ye +2 lly ee Hey = 1 
the reciprocal magnetic ellipsoid. Everything that has been said 
above of the eleciric ellipsoid, holds also good, if we substitute 
„maguetie” for ,electric’. If 7, and 7’, are again the radii vectores 
of the two magnetic ellipsoids, than 
1 Hos (B H) (17) 
aaa ae er ee eee 
me: 
1 _$Becos (BH) 
ae ee Ge (19) 
D 
if in the first case D falls in the direction of 7, and in the second 
H in the direction of rp. 
The principal axes of the two electric ellipsoids will be called 
electric principal axes, and those of the two magnetic ellipsoids, 
4* 
