as the greatest success yet achieved by any machine constructed on the
ornithopter principle.

It may be that, as forecasted by the prophet Wells, the flapping-wing
machine will yet come to its own and compete with the aeroplane in
efficiency. Against this, however, are the practical advantages of
the rotary mechanism of the aeroplane propeller as compared with the
movement of a bird's wing, which, according to Marey, moves in a figure
of eight. The force derived from a propeller is of necessity continual,
while it is equally obvious that that derived from a flapping movement
is intermittent, and, in the recovery of a wing after completion of one
stroke for the next, there is necessarily a certain cessation, if not
loss, of power.

The matter of experiment along any lines in connection with aviation is
primarily one of hard cash. Throughout the whole history of flight up to
the outbreak of the European war development has been handicapped on
the score of finance, and, since the arrival of the aeroplane, both
ornithopter and helicopter schools have been handicapped by this
consideration. Thus serious study of the efficiency of wings in
imitation of those of the living bird has not been carried to a point
that might win success for this method of propulsion. Even Wilbur Wright
studied this subject and propounded certain theories, while a later and
possibly more scientific student, F. W. Lanchester, has also contributed
empirical conclusions. Another and earlier student was Lawrence
Hargrave, who made a wing-propelled model which achieved successful
flight, and in 1885 was exhibited before the Royal Society of New South
Wales. Hargrave called the principle on which his propeller worked that
of a 'Trochoided plane'; it was, in effect, similar to the feathering of
an oar.

Hargrave, to diverge for a brief while from the machine to the man,
was one who, although he achieved nothing worthy of special remark,
contributed a great deal of painstaking work to the science of flight.
He made a series of experiments with man-lifting kites in addition to
making a study of flapping-wing flight. It cannot be said that he set
forth any new principle; his work was mainly imitative, but at the same
time by developing ideas originated in great measure by others he helped
toward the solution of the problem.

Attempts at flight on the helicopter principle consist in the work of De
la Landelle and others already mentioned. The possibility