2 3 4 D O C U M E N T 2 2 4 M A R C H 1 9 2 6 wires, or the intervals, as Δ, then the partial wave train has the length , which comes to 6 cm (30,000 volts) for the fastest hydrogen canal rays that E. Rupp has examined. Since Mr. Rupp still observed interferences at a 16 cm path difference,[4] the experiment certainly does lie within the precision limits achieved by this au- thor. If the experiment were to come out negative (or, i.e., the interferences were not inhibited by the presence of the grating) and the assumption were excluded that the emissions of different canal ray atoms were coherent with each other, this experi- ment would teach us that the radiation’s interference capacity had nothing to do with a periodicity characteristic of the emitting atom. Berlin, 16 March 1926. A. Einstein 224. From Hans Reichenbach [Ostheim, Stuttgart, Teckstrasse 75,] 16 March 1926 Dear Mr. Einstein, You may have heard that despite the efforts of Messrs. Planck and Laue my Um- habilitation to Berlin is still not completed, and it still cannot be assessed whether it may materialize at all.[1] It is certainly not possible to do anything about this, and I would like to let the matter run its course as it is currently going. However, I would like now to return to the discussion that I had with you in the fall as to whether there might possibly be a position for me in America. I just found out that there is an America Institute in Berlin,[2] Dorotheenstr., in the State Library building. The director is a Dr. Bertling.[3] This institute specifi- cally assists in the exchange of scientists with America. There, one can in any case find out where people are needed. I would like to ask you whether you can perhaps inquire by phone or by letter. I’m afraid if I do it myself, the plan is immediately doomed to fail also, the Berlin faculty could hold it against me if I myself under- took something different. Preferably, I would go over for a limited time. I would also very much like to take part in the Philosophers’ Congress that will take place in America in Septem- ber. Presumably, the philosophical problems of rel. th. will also be discussed, and I would very much like to be there for that, as, if Mr. Driesch goes as the only “spe- cialist” in this field on the German side[4] (as I have specifically found out), the c Δ v --- [p. 301]