3 5 0 D O C U M E N T 3 5 4 A U G U S T 1 9 2 6 must keep silent and let those speak who have something important to say that others don’t know yet. You will surely accept this reason for declining. I have la- bored a lot over finding the relation between gravitation and electromagnetism, but am now convinced that everything that has been tried by me and others in this direction was futile. I gladly concede to you that there can be no doubt about the spinning electron. But for the time being, there is little hope of understanding its necessity from the inside. Among the new attempts to obtain a deeper formulation of the quantum laws, the one by Schrödinger appeals to me most.[3] If only the wave fields intro- duced there could be transplanted from the n-dimensional coordinate space into the 3- or 4-dimensional one! The Heisenberg-Dirac theories certainly drive me to ad- miration, but to me they don’t smell of reality.[4] Warm regards, your A. Einstein 354. From Emil Rupp Göttingen, 21 August 1926 Dear Professor, A while ago I sent the manuscript of my paper to Privy Councillor Planck with the request for submission to the Academy.[1] Last week I received a letter that this submission would only be possible at the Academy’s next meeting, on October 26th.[2] I would now like to ask whether you are disposed to such a date. I added another section to the paper on the greatest interference length attained for Hβ—in response to Atkinson in Naturwissenschaften[3] —which shows that in my Habilitationsarbeit[4] I unconsciously conducted the turned-mirror experiment & in this way obtained interferences with path differences up to 15 cm. Here in Göttingen I had an opportunity to speak often with Prof. Franck[5] about my experiments. Prof. Franck sees as a major problem how it was possible by means of the turned-mirror experiment to compensate for an entire velocity region, as it arises as a consequence of the finite scattering angle of the atoms behind the canal. Respectfully and sincerely yours, E. Rupp