8 0 0 C H R O N O L O G Y 1 9 2 9 April 15 Attends speech by H. G. Wells on “Common Sense and World Peace” at the Reichstag followed by dinner in Wells’s honor at the Hotel Adlon (Vossische Zeitung, 15 April 1929, EE, and 16 April 1929, ME). Einstein Jubilee celebration held in honor of AE’s fiftieth birthday at the Metropolitan Opera House in New York (Jewish Daily Bulletin, 17 April 1929). ca. April 17 Travels to Düsseldorf and stays with the Lebach family. April 20 Appeal by the International Trotsky Assistance Committee cosigned by AE is published (Doc. 503). April 25 Visits Hans Albert in Dortmund and returns to Berlin. “Einstein Believes in ‘Spinoza’s God’ ” published (Doc. 508) in the New York Times. Receives patent DE 590 783 with Goldschmidt for sound reproduction using magnetostriction, a type of hearing aid (Doc. 509). April 28 Visits the family of Adolf Stern in Caputh and signs his name in their guest book. May 10 Makes statement on the eclipse expedition to Sumatra: “The successful observation at Sumatra of the Sun’s eclipse yes- terday constitutes enhanced confirmation of the theory of relativity, which, however, has been tested several times before” (New York Times, 11 May 1929). before May 17 Receives congratulations for fiftieth birthday from the Jewish community of Harbin, China (Sentinel, 17 May 1929). before May 18 Travels to Brussels for Solvay Scientific Committee meeting. May 18–20 Attends Solvay Scientific Committee meetings in Brussels. May 21 or 22 Returns to Berlin. before May 29 Sends message in support of OZE on the establishment of a national committee to sponsor its work in the United States (Jewish Daily Bulletin, 29 May 1929). May 30 Cosigns appeal for an Interdenominational Working Group for Peace (Doc. 538).