D O C U M E N T 5 2 3 M A Y 1 9 2 7 5 2 1 tential and arbitrarily short visit in Leyden would better fall before than after Brus- sels. BUT IT IS CERTAINLY NOT NECESSARY THAT YOU COME TO LEYDEN BUT THAT IT WOULD PLEASE ALL OF US VERY MUCH IS TRIVIAL!!!!!! III. Since your second paper on the statistics of ideal gases, I haven’t received any offprints from you. I ask Margot or your wife please to forward them to me and, if possible, in two copies.) Tanichka, in particular, is VERY, VERY interested (don’t let her notice that I’m writing this to you) in what the situation is with singular world lines. Couldn’t you present by letter which problems you can’t master yet? It seems not so impossible at all that Tanichka could perform cal- culations for you, once they’re formulated geometrically or in some other mathematical form. Tanichka is traveling to Göttingen for some weeks, after my wife’s arrival at the beginning of June. My dream is to see Tanichka working, in contact with you and Herglotz. Maybe she could happen to form the bridge between you and Her- glotz. For I don’t believe that there’s any better mathematician able to [explain] your intentions mathem[atically], in fine taste and with a true grasp, than Her- glotz. He doesn’t make a mathemat[ical] plague for physics out of his powerful mathematical ability. Warm regards to you and yours, your Ehrenfest 523. To the Chief of Police of Berlin-Schöneberg [Berlin, 18 May 1927] Petition for Dispensation To the Chief of Police of Berlin-Schöneberg: The Municipal Building Inspector’s Office sent me the enclosed order, accord- ing to which I must vacate the study exclusively used by me. I petition that this injunction be annulled. Justification: 1) The room is sunny (directed toward the east) and spacious, the window open- ing toward the east. Area c. 20 sq. m. 2) The official sent here by the Building Inspector’s Office acknowledged that the room is unobjectionable. However, the injunction was based on the claim that, according to the official listing, the room was not appropriate as living space. The injunction fails to take into account that the window has been enlarged.