be made as strong structurally as the other form,
owing to the lack of the truss formation which is
the strong point with the superposed frame. A
truss is a form of construction where braces can
be used from one member to the next, so as to
brace and stiffen the whole.

THE BIPLANE.--Nature does not furnish a type
of creature which has superposed wings. In this
particular the inventor surely did not follow nature.
The reasons which led man to employ this
type may be summarized as follows:

In experimenting with planes it is found that
a broad fore and aft surface will not lift as much
as a narrow plane. This subject is fully explained
in the chapter on The Lifting Surfaces of
Planes. In view of that the technical descriptions
of the operation will not be touched upon
at this place, except so far as it may be necessary
to set forth the present subject.

This peculiarity is due to the accumulation of
a mass of moving air at the rear end of the plane,
which detracts from its lifting power. As it
would be a point of structural weakness to make
the wings narrow and very long, Wenham many
years ago suggested the idea of placing one plane
above the other, and later on Chanute, an
engineer, used that form almost exclusively, in