0 Do» 4 Je So) afde), 
dt AE dt de de 
0 Doz d fo d Jo 
A  . 
af TCV EF ee) (10) 
2M. 1 92M, 
wos ya dt? 
FEE v? fo, ete. (11) 
we shall find 
0 €, dE mee 0 rd Me 0 My 9 0 Io dh, 
eN 
or, by (9) and (10), 
OE, AE dhe DE, DE DA, DE, JE, 34: an 
Peat sent Ee A dal co id blo 
The form of these equations shows that € is precisely the 
“electric force.” 
In virtue of (11) the equations (8) become 
v zx dM, ev rde dM, 0 M- 
—Mz+— => ( |=. ir ll 
q oT ve dt Mee Dt Ne i Er 
As we see, they express the relation between the electric force 
and the electric moment. 
Finally, from (9) we may deduce the formula 
d Diz 0 Diy ad d ie M, 3° My 9 M. bir | 
dy Ga tania dry dede et HL 
or, if (11) be taken into account, 
£ > 1 2 Mi : es ; 
Ren 5 : Nn as Fahd 
Oy edt de Noe def dt 
Combining this with 
d la d No- d Da, 
At = —— — ; 
dt dy dz 
Re 
