984 
0G, IP, 
dcp dap 
scalar potential p and the vector potential a of the theory of elec- 
trons are connected with our potentials: 
P, Pr Ps Po (=) ar ay az —ep. 
For the components of the force acting on the charge per unit 
of volume we found in our formula (10): 
— Ky =—V—ghy =A (m) Vg Wer fom- 
To make this agree with the above, we must, with a view to the 
choice of units, give the value 4=1/c’ to the coefficient 2. The 
formula thus becomes 
i 
= V9 hy = Em) Vg W fm 
It keeps this form when we pass to a system of coordinates 
in which tbe unit of time is c times smaller and in which the 
velocity of light becomes equal to 1 (¢ remains 3.10*°). It may be 
remarked in passing that in the papers of Lorentz’) and TREs1ING 
the factor 1/c? is failing. It is thus seen that they have silently used 
a unit of charge c times larger than the usual one. 
The scalar for the field becomes 
M= — tE (ab) Feb fy =F (CF — Ah), 
Hence it is evident how the 
We know that Tra = 
and the principal function 21/—gM = — (d’—A’). In agreement with 
I 
2e 
what has been said at the beginning of this paragraph this expression 
is c times smaller than the one we were accustomed to. 
The stresses, the negative momenta, the energy and the energy- 
currents become 
Vg Ey = AZB) V—g F™ fos — A —gda M, 
1 2 2 1 1 ] 
c 
1 ] 2 2 1 1 
C 3 c 2 
1 1 3! 2 1 
Sne sedd). —(hyhe-+dyd:), ze (he + add), — —(¢ij— ae 
¢ Cote PA c 
1 
(d,hz-—d-hy), (d:hy—dzh:), (d,hy—dyhz), 5e (i? + a’) 5 
| c 
We see that all these components become c times smaller than 
formerly, as has been remarked already in the beginning of this 
paragraph. 
1) For the comparison with the papers of LorENTz it may be remarked that 
V—g Fab = tab and far = vad. Further that V—gWm= wm. 
