D O C U M E N T 2 9 4 M A Y 1 9 2 6 3 1 1 these questions satisfactorily. In this hope I am fortified by the fact that if we con- sider an analytic function instead of a plane on a minimal surface, the residues ob- tain a geometric meaning that shows that all of them are of the same absolute magnitude. As time-space manifests conspicuous analogies with a minimal surface in other ways as well, it appears that it will not be impossible to derive the equality of the residues of the curvature field, i.e., the electric charges, from the correct field equations.[6] — I don’t want to let this letter grow even more but it would be an honor and a pleasure for me, if it should interest you, to send you a detailed expo- sition on this topic. You note at the end of your letter[7] that I should have set for the electric charge instead of the expression (2') . But the expression is not determined by the curvature field, whereas (2') is. If it were possible to carry through the standpoint of curved time-space con- sistently, we would have to assume (2') and try to derive the absence of magnetic charges, in a certain sense, from the field equations. This is indicated above under II. More precisely, we would expect that among the ∞' electromagnetic fields that are consistent with a given curvature field, there will be one in which no magnetic charges exist.[8] Respectfully yours, G. Y. Rainich 294. To Leo Kohn [Berlin,] 29 May 1926 Dear Mr. Kohn, I am in complete agreement with the time and place of the meeting of the Board of Governors.[1] Please be sure that a meeting of the Board of Governors of the Rosenbloom Foundation can be associated with it.[2] It is also important that the American doctors[3] be adequately represented. Regarding your idea to allow the Institute to be run from abroad by capable individuals, I consider this, in principle, not good, although individual cases may promise success. No good fellow will go to Palestine if such a condition of dependence is intended for him. This can be done only on a case by case basis. In general, the “authorities” have either already be- come senile or at least “saturated.” One must always look for competent young 0 xμdyν ³fμνd = ρ2 A xμdyν]2 ³rμνd [ = = A dxμ)dyν]2 ³fμν( [ xμdyν]2 ³rμνd [ + = xμdyν ³rμνd