The Smithsonian’s National Museum of American History has named David Allison as acting director after director John Gray suffered a heart attack last week. Gray, who started the job two months ago, was taken Tuesday to George Washington University Hospital, where he remains hospitalized in stable condition, reports our colleague Lonnae O’Neal Parker. Allison, the museum’s associate director of curatorial affairs, will fill in for an unspecified period, according to a spokeswoman.