Hence 
PE BB, A 
de T dt ’ | 
a ke (17) 
pmen TR \ 
D= 0 / 
Let the components of the dielectric displacement in the aether 
be f, g, h. Then 
EC, =Anv a, G,=4nvrh, 
and if, instead of (M,, M,, M.), we write (X, Y, Z) for the electric 
moment per unit of volume, 
Dr=f+Xx, y= It, Deh. 
Putting this in (17), we are led to the equations (16), which I 
have just taken from POINcARÉ. 
Again, if there be no resistance, our equations (4') may now be 
replaced by 
filet 4 : ns O° XR 
Np, — —awv? X + — = 
3 Ne}? dt 
Ne}? 
1 Fn Fi, 
Hoes See : 
Neh, 
} = 2 te. 
Di ey, Anv*f , ete 
Dividing this by 4a v*, and putting 
Zh 
oe eh 
4 nv? Ne)? 
fh en 1 
Anv? Ne? Ly’ 
1 
An v? Ne, : 
we find the above formulae (15). Porncark’s equations are thus 
found to be identical with mine. 
