These Congressional acts are part of "the supreme law of Gallaudet University."[43] Gallaudet must obtain authorization from the Secretary of the US Department of Education in order to sell or transfer title of any of its real property.[2] The diplomas of all Gallaudet graduates are signed by the current U.S. President, which dates from President U.S. Grant signing students' diplomas in 1872.[44] Three members of Congress are appointed to the university's board of trustees as "Public Members."[45] Gallaudet must provide annual reports to the Secretary of Education.[46] "Gallaudet receives the bulk of its income in the form of an annual appropriation from Congress, and the Department of Education oversees the University's appropriation for the Federal government."[47] Gallaudet University (and the National Technical Institute for the Deaf) are authorized to make purchases through the General Services Administration.