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 in Opposite directions, but the
power was not sufficient to lift the model. De la Landelle's
principal achievement consisted in the publication in 1863 of a
book entitled Aviation which has a certain historical value; he
got out several designs for large machines on the helicopter
principle, but did little more until the three combined in the
attempt to raise funds for the construction of their
full-sized machine. Since the funds were not forthcoming,
Nadar took to ballooning as the means of raising money;
apparently he found this substitute for real flight sufficiently
interesting to divert him from the study of the helicopter
principle, for the experiment went no further.

The other experimenter of this period, one Count d'Esterno, took
out a patent in 1864 for a soaring machine which allowed for
alteration of the angle of incidence of the wings in the manner
that was subsequently carried out by the Wright Brothers. It
was not until 1883 that any attempt was made to put this patent
to practical use, and, as the inventor died while it was under
construction, it was never completed. D'Esterno was also
responsible for the production of a work entitled Du Vol des
Oiseaux, which is a very remarkable study of the flight of
birds.

Mention has already been made of the founding of the
Aeronautical Society of Great Britain, which, since 1918 has
been the Royal Aeronautical Society. 1866 witnessed the first