322 On Electromagnetic Effects due to the Motion of the Earth. 
Hence the complete value for the electromotive intensity at a point, due to a 
current in a conductor, when both the point and conductor are moving, 1s 
6—(S(—9)4)" 
2.e., its components are 
LER al GEE eed 
50) aie * OO? OV 
nC Cee MER Cum MRC Oy 
Q=(é - @) Te + 0 Vay +(G- 2“) Te 
9 o@hBlL © o@jlel 5 o@ilal 
WAG S6) as =a * Oa 
The mechanical force at the point, as given by Maxwell, is 
e— VBE = eA, 
1.e., its components are 
dy 
XM=cv—bw — a= 
die 
dv 
Y—aw—cu—e=— 
dy 
Ie 
Z= bu—av—eF 
The electromotive intensity at the point, as given by Maxwell, is 
7.¢., its components are 
dG dv 
ia dy 
Now there does not seem any reason why the mechanical force should not be 
written 
5=VBC+eE 
i.¢., its components are 
X =cv—bw+eP 
Y =aw—cu+eQ 
Z=vu—-—av+eR 
for is it not the meaning of the electromotive intensity, that the mechanical force 
due to it on a quantity of electricity, e, is e ¢? Although in his enumeration of the 
equations of the electromagnetic field, Maxwell gives the equations as at first cited, 
vetin § 631, where he is deducing the general expression for the electrostatic energy 
of the field, he practically assumes that the second expression I have given is the 
true one. Hence the mechanical force at a point moving with a velocity p and 
carrying a current 6, and charged with a quantity of electricity e, is 
BC + VB, Gy 
T=VBE + eVBo —eF, —cAV 
