Second Exhibition of the Metropolitan Mechanics' Institute, by Unknown, 1855, Smithsonian Archives - History Div, "Second Exhibition of the Metropolitan Mechanics' Institute." Engraving shows people gathered on the Smithsonian grounds for the fair of the Metropolitan Mechanics' Institute (MMI). The fair was held on February 8, 1855, in the Great Hall of the Smithsonian Institution Building, "Castle," and was the first public use of the space. Joseph Henry, the first Secretary of the Smithsonian (1846-1878), was also president of the MMI..