experimenting with his gliders.

It was due to his influence that the Wrights
adopted that form in their gliding experiments,
and later on constructed their successful flyers
in that manner. Originally the monoplane was
the type generally employed by experimenters,
such as Lilienthal, and others.

STABILITY IN BIPLANES.--Biplanes are not naturally
as stable laterally as the monoplane.
The reason is, that a downward tilt has the benefit
of only a narrow surface, comparable with the
monoplane, which has broadness of wing.

To illustrate this, let us assume that we have
a biplane with planes five feet from front to rear,
and thirty-six feet in length. This would give
two planes with a sustaining surface of 360 square
feet. The monoplane would, probably, divide
this area into one plane eight and a half feet from
front to rear, and 42 feet in length.

In the monoplane each wing would project out
about three feet more on each side, but it would
have eight and a half feet fore and aft spread
to the biplane's five feet, and thus act as a greater
support.

THE ORTHOPTER.--The term orthopter, or ornithopter,