D O C . 3 6 8 O N U N I F I E D F I E L D T H E O R Y 3 5 1 Making use of (6), we eliminate from (5a) to obtain … (5b) This equation, in connection with … (4a) and using the identity , which can be derived by applying the divergence- commutation relation to …, (7) forms the basis for the following considerations. We set out the equations … (8) … (9) , … (10) Between these 4 + 16 + 4 equations, the four 4 + 4 + 4 identity relations (5b), (4a), and (7) hold, so that of the 24 equations, only 12 are independent. These equations will thus be suitable for determining the 16 (= 12 + 4) field variables . Taking into account (3) and (2), equations (10) gives , which is equivalent to the electromagnetic equations … (10a) We thus arrive at the system of equations (8), (9), and (10a). There,  is an arbi- trary constant (cf. (3)). Now, it is my opinion that one must choose . Con- sidering the first approximation indeed shows that only this choice of  makes centrally symmetric electric fields possible obey the equations. For the complete system of field equations, we thus find A. Einstein G H 1 2 S   +    / V//  0  – H/ 0  S  S/  1 2 S   –    / 0  S  0 = H 0 =  G  = V//  0 = h s W // 0 = h       –   / 0 = [p. 5]  0 = [7] 1 h --S        + + 0 = = G H V / 1 2 --V    – 0 = = = h       –   / 0 =