6 4 D O C . 3 1 C A L C U L A T I O N S Dated by the fact that the calculations are written on the back of Abs. 56. The formulation of the affine field theory found in Einstein 1923e (Vol. 13, Doc. 425) in terms of a Hamiltonian principle was first given in Einstein 1923h (Doc. 13). Calculations pertaining to the variational formulation of this paper can be found in Einstein’s Japan diary (Vol. 13, Doc. 418, [p. 43]). The variational calculations in the present document appear to be related to the variational principle as given in Einstein 1923n (Doc. 52), eq. (13). This equation is the starting point for an experimental investigation carried out by Hermann Mark in late summer 1923 see Doc. 152.