The aircraft was the Cornu 1907 machine. It is not clear though whether this machine ever truly attained controlled flight in any sense (see Cornu's Helicopter - First in Flight, Professor J. Gordon Leishman, VERTIFLITE Fall/Winter 2001, Page 54), but it does represent the first attempt to use a longitudinal tandem configuration for a rotorcraft.

Source: "The American Helicopter | An Overview of Helicopter Developments in America 1908-1999", Michael J. Hirschberg, July 2000, Page 3