The history of the office of Assistant Secretary can be traced to January 26, 1847 when the Smithsonian Board of Regents approved the nomination of Charles C. Jewett, of Brown University, for the position of Assistant Secretary, acting as Librarian. On July 5, 1850 the Board resolved "...that the Secretary be authorized to appoint an assistant secretary in the department of natural history, to take charge of the museum, and to render such other assistance as the Secretary may require...." Shortly thereafter, Spencer F. Baird was appointed to the position. During various periods of time, the Assistant Secretary was also in charge of publications, exchanges, and other areas. Incumbents included: (1) Spencer F. Baird, 1850-1878; (2) George Brown Goode, 1881-1896, including the years 1881-1887 when he served as assistant director of the museum without the title of Assistant Secretary; (3) Charles D. Walcott, Acting Assistant Secretary, 1897-1898; (4) Richard Rathbun, 1897-1918. During certain periods of time, the business of the office was administered by the Executive Curator, Frederick William True.
Richard Rathbun's (1852-1918) association with the Smithsonian Institution began in 1873 when Spencer F. Baird appointed him volunteer assistant in the United States Commission of Fish and Fisheries (USCFF). In 1878, Rathbun was appointed scientific assistant in the USCFF and detailed to New Haven, Connecticut to work on the collection of marine invertebrates in the custody of Addison Emery Verrill. He was transferred to Washington in 1880 and the following year was appointed honorary curator of the Department of Marine Invertebrates in the U. S. National Museum (USNM), a position he continued to hold until 1914. He continued his concurrent duties with the USCFF and USNM until 1896, when he accepted appointment to the position of Assistant Secretary of the Smithsonian Institution, in charge of Office and Exchanges. After the resignation of Charles D. Walcott as Assistant Secretary, in charge of the National Museum in 1898, Rathbun's duties were revised to include certain aspects of museum administration. During this time the Executive Curator, Frederick William True was the officer in immediate charge of the museum. In January, 1901, Rathbun was made Assistant Secretary, in charge of the National Museum, in which capacity he remained until his death in 1918. On the death of Secretary Samuel P. Langley in February, 1906, Rathbun assumed the duties of Acting Secretary until the election of Charles D. Walcott in 1907. Major accomplishments of Rathbun's Assistant Secretarial years included the completion of the Children's Room of the Smithsonian Institution, 1901; the development of the National Gallery of Art, 1904-1910 (after 1937 known as the National Collection of Fine Arts); and the construction of the new National Museum building completed in 1911.