Tennis Courts Behind SI Building, by Unknown, 1920, Smithsonian Archives - History Div, Loyal B. Aldrich of the Smithsonian Astrophysical Observatory (1908-1955) and Astrophysicist Charles Greeley Abbot (Fifth Secretary of the Smithsonian, 1928-1944) playing tennis behind the Smithsonian Institution Building, next to the Smithsonian Astrophysical Observatory, in the South Yard. The National Air Museum temporary metal building is in the background..