Two abortive attempts characterised the sixties of last century in France. As regards the first of these, it was carried out by three men, Nadar, Ponton d'Amecourt, and De la Landelle, who conceived the idea of a full-sized helicopter machine. D'Amecourt exhibited a steam model, constructed in 1865, at the Aeronautical Society's Exhibition in 1868. The engine was aluminium with cylinders of bronze, driving two screws placed one above the other and rotating.
Used availability for E Charles Vivian's The History of Aeronautics