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 of flight by this method is modified by a very
definite disadvantage of which lovers of the helicopter seem to
take little account. It is always claimed for a machine of this
type that it possesses great advantages both in rising and in