Secretary Charles G. Abbot with Bolometric Apparatus, by Unknown, 1900, Smithsonian Archives - History Div, Charles Greeley Abbot, then Acting Director of the Smithsonian Astrophysical Observatory (SAO), pictured with bolometric apparatus, was one of a team of Smithsonian scientists who traveled to Wadesboro, North Carolina, to study an eclipse of the sun in 1900. Abbot later became director of the SAO and Fifth Secretary (1928-1944) of the Smithsonian..