9.8 End of an Era
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Kohlschütter himself had left the United States shortly after the outbreak
of war. He had tried to reach Germany via Gibraltar, but was arrested there
and held prisoner of war for the rest of the war. Eventually he was transferred
to England, where Arthur Eddington enabled him to do some astronomical
work. The war prevented further visits to Mount Wilson. Kapteyn actually has
never returned there. He did remain a paid Research Associate of the Carnegie
Institution for the rest of his life, although he had great difficulty accepting
this, so that Hale had to convince him a few times to do so, saying that the
Institution appreciated his work for them enormously and did not care where
it was done. It had been a very productive and auspicious time for both parties.
George Hale later wrote to Willem de Sitter:
Nothing has been so valuable to the Mount Wilson Observatory as the inspiration
and guidance of Kapteyn. His splendid imagination and fine optimism have
stimulated us to our best efforts and encouraged us to attack problems of wide
scope.