d rise from the ways
of itself. The whole problem of the successful flying-machine is,
therefore, that of arranging an aeroplane that shall move through the
air with the requisite speed.

The practical difficulties in the way of realizing the movement of such
an object are obvious. The aeroplane must have its propellers. These
must be driven by an engine with a source of power. Weight is an
essential quality of every engine. The propellers must be made of
metal, which has its weakness, and which is liable to give way when its
speed attains a certain limit. And, granting complete success, imagine
the proud possessor of the aeroplane darting through the air at a speed
of several hundred feet per second! It is the speed alone that sustains
him. How is he ever going to stop? Once he slackens his speed, down he
begins to fall. He may, indeed, increase the inclination of his
aeroplane. Then he increases the resistance to the sustaining force.
Once he stops he falls a dead mass. How shall he reach the ground
without destroying his delicate machinery? I do not think the most
imaginative inventor has yet even put upon paper a demonstratively
successful way of meeting this difficulty. The only ray of hope is
afforded by the bird. The latter does succeed in stopping and reaching
the ground safely after its flight. But we have already mentioned the
great advantages which the bird possesses in the power of applying
force to its wings, which, in its case, form the aeroplanes. But we
have already seen that there is no mechanical combination, and no way
of applying force, which will give to the aeroplanes the flexibility
and rapidity of movement belonging to the wings of a bird. With all the
improvements that the genius of man has made in the steamship, the
greatest and best ever constructed is liable now and then to meet with
accident. When this happens she simply floats on the water until the
damage is repaired, or help reaches her. Unless we are to suppose for
the flying-machine, in addition to everything else, an immunity from
accident which no human experience leads us to believe possible, it
would be liable to derangements of machinery, any one of which would be
necessarily fatal. If an engine were necessary not only to propel a
ship, but also to make her float--if, on the occasion of any accident
she immediately went to the bottom with all on board--there would not,
at the present day, be any such thing as steam navigation. That