983 
it takes the form 
2 2 
1 1 
Comparing this with what we were used to write in the old 
mechanics of relativity 
2 
3 0 =d | — me? Y1—v'/e? dt, 
1 
we see that in our formulae the function of LAGRANGE has been 
taken c times smaller. Correspondingly definite forces, energy, 
stresses etc. will have to be represented by numbers which are c 
times smaller than they were formerly. 
If for instance the unit of electric charge is left as it is defined 
in the theory of electrons (in these units an electron has e.g. a charge 
—Via Xx 4,65 x 10-10), and if at the same time the unit of the 
intensity of the electric field d and that of the magnetic field / are 
left unchanged, we shall have to write for the force per unit of volume 
1 1 
den Kek 
Cc C 
If we wish our equations (3) for the electric field 
0 
ENV We, 
LE 
in which the components of the current W—g Wa are ev, Qvy, QVz, 
0, to agree with the well known relations 
oh oh, 0 
c Ee oles rh be etc., 
the components of the contravariant field tensor must be 
1 
Od oa oe 
Cc 
1 
—h: 0 he —-—dy 
c 
Fab (=) 1 
ee ree 
c 
1 1 1 
deld ie ee 
c CG. C 
Hence it follows for the components of our covariant field tensor 
0 h, —h, ce dy 
= (ab) gap Jog F® = fog (=) —hz 0 hy edy 
Ruse etek Ute vd 
—cd, —ed, —ed: Wy 
