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In two scientific sidelights, Einstein continued his substantive assistance to his
cousin Edith Einstein in completing a doctoral dissertation, under the supervision
of Paul Epstein, on the theory of the radiometer (Docs. 38 and 42), and began his
own study of the gravitational field of globular clusters (Doc. 231). His motivation
for this was, most likely, that such a study would provide evidence for the existence
of the cosmological constant, though this hope was dashed.
V I
In one of the last letters of the year 1920, Einstein responded to Ernest Pickworth
Farrow, a botanist at Trinity College, Cambridge, who had heard rumors that Ein-
stein was not happy in Berlin. Farrow had inquired unofficially whether Einstein
might consider coming to Cambridge “if the finances could be arranged.” He also
attached a (nonextant) Christmas card for Einstein’s amusement. In a draft in Ilse
Einstein’s hand, dated 28 December, Einstein responded: “Your Christmas card is
truly of exquisite humor and tickled me very much, the more so since I am just
cramming English vocabulary, by the sweat of my brow, into my no longer youthful
brain” (Doc. 245).
Einstein’s training in the English language, however, was motivated not by any
academic or other ties to England; rather, he was preparing for a trip to the United
States. Earlier in the year, Einstein had been contemplating a visit to Spain and the
United States in 1921, was debating whom to take along, and had tentatively invit-
ed Ilse to accompany him (Docs. 162 and 165). On 15 December he had informed
his sons, “during the summer I am probably going on a half-year-long lecture tour
to North America” (Doc. 232).
Einstein had received invitations from several universities and academic institu-
tions in the United States, among them Princeton University, the University of Wis-
consin, and the National Academy of Sciences in Washington, D.C. Communica-
tion between Einstein and the various institutions and their representatives was dif-
ficult and involved frequent delays, exacerbated by Einstein’s absence from Berlin
between 13 September and 7 November. In his negotiations with the American in-
stitutions, Einstein had hoped to “buy” his “financial freedom” by asking for con-
siderable remuneration (Doc. 209). By the time he responded to Farrow, he may
have been expecting his demands to be met. But just a few days earlier, Princeton’s
president, John G. Hibben, had sent off a letter informing Einstein “that it will be
impossible to consider the honorarium of $15,000 which you request for your lec-
tures” (Doc. 243).
Thus, for the time being, the planned “Dollar-Reise” (Doc. 244) was shelved.
Nevertheless, his first visit to the New World would soon become the major event