3 0 4 D O C . 3 1 3 O N C U R R E N T S T A T E O F F I E L D T H E O R Y (12a) Then, with the aid of the Hamilton function . (13) one can make use of the variational principle (14) for those variations of the μ h ν that vanish at the limits of integration. One thus ob- tains 16 equations for the 16 field variables h.— The elaboration and physical interpretation of this theory is made more difficult by the fact that there is no a priori condition for the choice of ratios of the constants A, B, and C. It is found that with the choice of constants [19] (15) the resulting field equations agree to first order with the known laws of the gravi- tational field and of the electromagnetic field. A calculation that I have carried out with Mr. Müntz[20] even showed that the field of a mass point without electric charge is obtained just as well with the present theory as with the original general relativity theory. The derivation and discussion of the field equations will be given elsewhere. One should only mention that the specialization1 expressed in (15) should be intro- duced first only in the field equations, and not already in (14), since otherwise the equations for the electromagnetic field will be lost.[21] After these initial results, I have hardly any doubts that the combination of the Riemannian metric with the postulate of the existence of distant parallelism yields the natural representation of the physical properties of space in the framework of field theory. In the meantime, a deeper analysis of the general properties of the structures devel- oped above has convinced me that the most natural approach to the field equations does not emerge from Hamilton’s principle, but rather from some other method (cf. Sitz.-Ber. d. preuss. Akad. 1929. I).[22] 1 At least the choice of B = A. J 1 g    = J 2 g        = J 3 g  g  g        =        H h   J hJ = =  d H 0 = B A – = C 0 =   