weight of the wings themselves, but also that of
the engine and the engineer as well. Men also know how to build engines
and' screws of sufficient lightness and power to drive these planes
at sustaining speed. Inability to balance and steer still confronts
students of the flying problem, although nearly ten years have passed
(since Lilienthal's success). When this one feature has been worked out,
the age of flying machines will have arrived, for all other difficulties
are of minor importance.

'The person who merely watches the flight of a bird gathers the
impression that the bird has nothing to think of but the flapping of
its wings. As a matter of fact, this is a very small part of its mental
labour. Even to mention all the things the bird must constantly keep in
mind in order to fly securely through the air would take a considerable
time. If I take a piece of paper and, after placing it parallel with
the ground, quickly let it fall, it will not settle steadily down as
a staid, sensible piece of paper ought to do, but it insists on
contravening every recognised rule of decorum, turning over and darting
hither and thither in the most erratic manner, much after the style of
an untrained horse. Yet this is the style of steed that men must learn
to manage before flying can become an everyday sport. The bird has
learned this art of equilibrium, and learned it so thoroughly that its
skill is not apparent to our sight. We only learn to appreciate it when
we can imitate it.

'Now, there are only two ways of learning to ride a fractious horse: one
is to get on him and learn by actual practice how each motion and trick
may be best met; the other is to sit on a fence and watch the beast
awhile, and then retire to the house and at leisure figure out the best
way of overcoming his jumps and kicks. The latter system is the safer,
but the former, on the whole, turns out the larger proportion of good
riders. It is very much the same in learning to ride a flying machine;
if you are looking for perfect safety you will do well to sit on a fence
and watch the birds, but if you really wish to learn you must mount
a machine and become acquainted with its tricks by actual trial. The
balancing of a gliding or flying machine is very simple in theory. It
merely consists in causing the centre of pressure to coincide with the
centre of gravity.'

These comments are taken from a lecture delivered by Wilbur Wright
before the Western Society of