CUSHING1 writes that Osler was abroad on one of his periodic "brain dustings" when he noted in his commonplace book on June 17, 1884: "Telegraphed Tyson from Leipzig that I would accept Professor of Clinical Medicine in the University of Pennsylvania, 'Yes.' " In a letter to George Ross, written a few days later, Osler states that he had just received an unofficial letter from Dr. James Tyson, at that time professor of pathology at the University of Pennsylvania, asking him if he would accept the appointment if selected, and that he had replied in the affirmative.
Cushing gives Osler's own story of the matter as recounted in 1916, before a club of American Rhodes Scholars at Oxford:
I was resting in a German town when I received a cable from friends in Philadelphia, stating that if I would accept a professorship there I should communicate with Dr. S. Weir
PACKARD FR. WILLIAM OSLER IN PHILADELPHIA 1884-1889. Arch Intern Med (Chic). 1949;84(1):18-25. doi:10.1001/archinte.1949.00230010028006