580 DOCUMENT 491 DECEMBER 1913 I hope that all is well and good in Haarlem and that you and Mevrouw and Ru[11] are well. Will you give them my sincere regards? But now I will not take up any more of your time. Signing with respectful regards, yours as ever A. D. Fokker [1]Hermann von Helmholtz Arthur Schuster. [2]Probably Eva Bruins and Catherine Frankamp Confiserie Huguenin & Cie. at Bahnhof- strasse 39, Zurich. [3]On 7 November (see Doc. 482). [4]The curly brackets are in the original. [5]The problem of the energy of an electric dipole in a radiation field had earlier been dis- cussed by Einstein in his Solvay lecture (see Einstein 1914a [Vol. 3, Doc. 26], p. 339, where he mentions his failure to solve the problem). In a letter of late November 1911 to H. A. Lorentz (Doc. 313) he outlined a solution. The problem was also taken up in Einstein and Stern 1913 (Vol. 4, Doc. 11), which was published 20 March 1913. The results reported below are published in Fokker 1914. [6]Fokker 1913. The equation below is given in Fokker 1914 without a derivation a deriva- tion appeared in Fokker 1917 (which is dated December 1913). [7]A factor L is missing in the right-hand side of the following equation. [8]See Eucken 1912. [9]Einstein was planning to take up his position in the Prussian Academy of Sciences at the beginning of April (see Doc. 487). [10]Otto Stern. [11]Aletta Lorentz-Kaiser and son Rudolf. 491. To Rosa Bandi-Winteler [Zurich,] 7. Dez. 1913. Sehr geehrte Rosa! Es thut mir sehr leid, dass Sie nun schon wieder in Geschäftssorgen gera- ten.[1] Es ist selbstverständlich, dass ich alles thue, was möglich ist, um Ihnen dienlich sein zu können. Ich bin auch bereit persönlich hinzugehen, wohin Sie es für dienlich halten. Ebenso bin ich gerne bereit, mir als Unbeteiligter ev. Verträge oder dergl. zu überlegen. Wenn Sie mich persönlich etwas fragen wollen, so bitte ich Sie, aufs Institut[2] zu kommen, damit die maldicenza[3] der Mitmenschen keine Nahrung finde.[4] Mit besten Grüssen Ihr Albert Einstein. ALSX (Estate of Ernst Bandi, Bern). [76 202]. The envelope is addressed to "Frau Rosa Bandi Bederstr. 49 Zürich." and postmarked "Zürich 8 (Fluntern) 8.XII.13.XI." [1]Bandi-Winteler was planning to open a boardinghouse in the town of Winterthur (see Doc. 500) after moving to Zurich in late August 1913 (see Einwohnerkontrolle, SzZ-Ar).