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Dr. Sawyer was in Brazil from May 15 to June 26, 1930, to inspect the Rockefeller Foundation's yellow fever work there. He brought 200 white mice with him, so that the yellow fever lab in Bahia could begin using the recently developed mouse protection test for determining immunity to yellow fever. In this letter, he described some of the sights seen, including the "Graf Zeppelin" airship, one of the technological wonders of the late 1920s.