e lateral balance by shifting the weight of the operator's
body. This method seemed to them 'incapable of expansion to meet large
conditions, because the weight to be moved and the distance of possible
motion were limited, while the disturbing forces steadily increased,
both with wing area and with wing velocity'. Accordingly they invented a
method of warping the wings, to present them to the wind at different
angles on the right and left sides. Thus the force of the wind was used
to restore the balance which the wind itself had disturbed. But in their
early gliders this warping process acted in an unexpected way. The wing
which, in order to raise that side of the machine, was presented to the
wind at the greater angle of incidence often proved to be the wing which
lagged and sank. The decrease in speed, due to the extra drag, more than
counterbalanced the effect of the larger angle. When they attempted to
remedy this by introducing a fixed vertical vane in the rear, 'it
increased the trouble and made the machine 'absolutely dangerous'. Any
side-slip became irrecoverable by causing the vertical fixed vane to
strike the wind on the side toward the low wing, instead of on the side
toward the high wing, as it should have done to correct the balance.
'It was some time', the brothers remark, 'before a remedy was
discovered. This consisted of movable rudders working in conjunction
with the twisting of the wings.' So that now three different parts of
the machine had to be controlled by wires, worked swiftly and correctly
by the operator, to preserve the balance. There were the wing tips which
had to be warped. There was the horizontal vane in front which had to be
adjusted, to keep the machine in level flight or to bring it to the
ground. There was the vertical vane behind which had to be moved this
way and that to secure the desired effect from the warping of the wings.
'For the sake of simplicity,' says Wilbur Wright, 'we decided to attach
the wires controlling the vertical tail to the wires warping the wings,
so that the operator, instead of having to control three things at once,
would have to attend to only the forward horizontal rudder and the wing
warping mechanism; and only the latter would be needed for controlling
lateral balance.'

The thing was done. They had built an aeroplane that could fly; and the
later introduction of an engine was as simple a matter as the harnessing
of a horse to a carriage. 'With this appara