1 3 2 D O C S . 1 5 4 , 1 5 5 N O V E M B E R 1 9 1 9 (m sphere’s mass, that of the displaced fluid). I have in view here the drag with regard to the fluid layer in which the center lies that more can be ab- stracted from m than from is explained in that the sphere, owing to its size, lies partially in somewhat higher and lower lying layers, which drag less against the walls than the central one. Once again, many thanks for your visit, and our cordial greetings. With best wishes for your homeward trip[3] and for your health, faith- fully yours, H. A. Lorentz. 154. From Paul Ehrenfest [Leyden,] 3 November 1919 Dear, dear Einstein, You have left great waves of sympathy and friendship behind in this land, which will lap back and forth between us all, a long time from now. You really made ev- eryone completely happy and “boundlessly optimistic.”[1] Now I and all of us would very much like to know how you arrived home. With- out problems? (Did you have to stand?) Without being overly tired out? Please, couldn’t your wife write us briefly about that? I am going to write you more soon. We all—but especially the children[2] —send you boisterous greetings, P. Ehrenfest. Regards to your wife. Was the Thermos flask of any service to you?—My aunt gave us the idea![3] Full of concern for you. 155. To Hugo Bergmann Berlin, 5 November 1919 Dear Doctor Bergmann, I have warm sympathy for the affairs of the new colony in Palestine and espe- cially for the as yet to be founded university.[1] I shall gladly do everything in my power for it. I shall be happy to attend the conference you mentioned,[2] provided circumstances permit it. It is my pleasure to be able to inform you that other Jewish colleagues also show great interest in the Jewish university.[3] In particular, I want to mention Dr. Paul Epstein, cur[rently] at the University of Zurich, who in the last m 7m′ 4 -- - – m′ m′