982 
Le OV -gH 0 OV -gH _ 
= p= ZY lb 1 NEN rak we eo of 
V-9 80 (bd) gi, Ce Pa on Ded Ògied 
da o V-gH, 
which is found as se as 1/—gz, by transformation of the second 
term of the identity (21). 
If we wish we may take the components of one of these complexes 
for the stresses, momenta ete. in the gravitation field. According 
o (21) we have however sa te 
= (m) — Lw —9 Za) = 2 (©) U za) = > (e) Ws rs 
so that we me also 
m 
0 m 
V—g(Ta + Ea) 5 WI Za) = 0. . (24) 
= (m) 
Vin 
Now it is quite a matter of taste and, as to the calculations one 
of opportunity, which of the three equations (22), (23) or (24) will 
be regarded as the expression of the laws of conservation of energy 
and of momentum and whether zo, s, will be regarded as a dyna- 
mical quasi-tensor, or Z; as the dynamical pure tensor of the 
gravitation field; or finally whether it is better not to introduce a 
dynamical tensor in the gravitational field at all. 
Connexion with Lorentz’s theory of electrons. 
19. Finally we shall shortly show how the deduced formulae 
are connected with the classic formulae of the theory of electrons. 
For this purpose we must treat the case of constant gravitation 
potentials having the values 
—1 0 0 0 
CHS late Or 
0 0 —l Os 
0 0 0 c 
To these corresponds the value g—=-—c? and the values of the 
algebraic complements 
—l 0 0 0 
gy 0 SI Ee 0 
0 0 —l Le 
1 
0° Se eee 
C 
Our formulae are based on HamrrroN’s principle for the motion 
of a point which falls freely. In the case now under consideration 
