528 APPENDICES
1928 February or March. E. suffers a temporary physical collapse brought about
by physical overexertion. An enlargement of the heart is diagnosed. He has
to stay in bed for four months and must keep a salt-free diet. He fully recu-
perates but remains weak for almost a year.
Friday, the thirteenth of April. Helen Dukas starts to work for E.
1929 First visit with the Belgian royal family. Friendship with Queen Elizabeth,
with whom he corresponds until the end of his life.
June 28. Planck receives the first, E. the second Planck medal. On this
occasion E. declares that he is 'ashamed' to receive such a high honor since
all he has contributed to quantum physics are 'occasional insights' which
arose in the course of 'fruitless struggles with the main problem.'
1930 Birth of Bernhard Caesar ('Hardi'), son of Hans Albert and Frida E., E.'s
first grandchild.*
May. E. signs the manifesto for world disarmament of the Women's
International League for Peace and Freedom.
November 29. Margot E. marries Dimitri Marianoff. (This marriage
ended in divorce.)
December 11-March 4, 1931. E.'s second stay in the United States,
mainly at CalTech.
December 13. Mayor Jimmy Walker presents the key to the city of New
York to E.
December 19-20. E. visits Cuba.
1931 April. E. rejects the cosmological term as unnecessary and unjustified.
December 30-March 4, 1932. E.'s third stay in the United States, again
mainly at CalTech.
1932 February. From Pasadena E. protests against the conviction for treason of
the German pacifist Carl von Ossietzky.
April. E. resigns for good from the CIC.
October. E. is appointed to a professorship at The Institute for Advanced
Study in Princeton, New Jersey. The original intent is that he divide his
time about evenly between Princeton and Berlin.
December 10. E. and his wife depart from Germany for the United
States. This stay was again planned to be a visit. However, they never set
foot in Germany again.
1933 January 30. The Nazis come to power.
March 20. In his absence, Nazis raid E.'s summer home in Caputh to
look for weapons allegedly hidden there by the Communist party.
March 28. On his return to Europe, E. sends his resignation to the Prus-
sian Academy. He and his wife settle temporarily in the villa Savoyarde in
Le Coq sur Mer, on the Belgian coast, where two Belgian security guards
are assigned to them for protection. They are joined by Use, Margot, Helen
Dukas, and Walther Mayer, E.'s assistant. During the next few months, E.
makes brief trips to England and also to Switzerland, where he sees his son
Eduard for the last time. Rudolf Kayser sees to it that E.'s papers in Berlin
are saved and are sent to the Quai d'Orsay by French diplomatic pouch.*A second grandson died at age six. By adoption, E. also had a granddaughter named Evelyn.