D O C U M E N T 3 6 5 O N U N I F I E D F I E L D T H E O R Y 3 4 7 , (11) which system of equations, together with , (10a) forms the complete system of field equations. If we had started directly from (10) instead of from (10a), we would not have obtained the “electromagnetic” equations (11). We would have also not obtained any indications that the systems (11) and (10a) are compatible with each other. Thus, however, it seems to be certain that these equations are mutually compatible, since the original equations (10) consist of sixteen conditions for the sixteen quan- tities s h μ . There are necessarily 4 identity relations connecting these sixteen equa- tions (10), owing to the general covariance of the equations. Between the 20 field equations (11) and (10a), there are thus altogether 8 identity relations, of which, however, only 4 are given explicitly in the text. That equations (10a) contain the gravitational equations to first approximation, and equations (11) (in connection with the existence of a potential vector) contain the Maxwell equations in vacuum, has already been mentioned. I have also been able to show that conversely, for every solution of these equations, an h field exists1 that obeys the system of equations (10a). By contraction of equations (10a), one ob- tains a divergence condition for the electric potential: . (12) A deeper investigation of the consequences of the field equations (11) and (10a) will be required to show whether the Riemannian metric, together with distant par- allelism will indeed yield an adequate description of the physical qualities of space. From the present investigation, this seems not improbable.[20] It is my pleasant duty to thank Dr. H. Müntz[21] for his laboriously precise cal- culation of the centrally symmetric problem on the basis of Hamilton’s principle the results of his calculation suggested to me the method used here. Likewise, I wish to thank here the Physikalischer Fond,[22] which has made it possible for me in the past yeas to hire a research assistant in the person of Dr. Grommer.[23] Note added in proofs: The field equations proposed in the present work should be formally distinguished from other imaginable equations as follows:[24] with the help of identity (8) it has become possible to subject the (16) quantities s h μ not only to 16, but to 20 independent differential equations. “Independent” is here to be un- derstood in the sense that not one of these equations can be derived from the others, although among them there are 8 identity (differentiation) relations. 1 This holds only insofar as we are dealing with the linear equations in the first approximation. h  k    k –   / 0 = V kl l   V k     – 0 = [p. 7] f l /l 1 2 -- V k     – 0 = l 2f V l  2h l  = =     