WASHINGTON, DC.- Marc Pachter, former director of the Smithsonian’s National Portrait Gallery, has been appointed Acting Director of the National Museum of American History, effective Aug. 15. He will replace Brent D. Glass, who announced that he was leaving the directorship in August and retiring from Smithsonian at the end of the year. Pachter was with the Portrait Gallery for 33 years, beginning as a chief historian in 1974 and serving as director from 2000 until his retirement in 2007. He held a number of positions at the Gallery and at the Smithsonian when he served as chair of the Institution’s 150th anniversary celebration in 1996 and as a deputy assistant secretary for external affairs. Pachter retired in October 2007, one year after the National Portrait Gallery and the Smithsonian American Art Museum, which share the same historic building