AREA NOT THE ESSENTIAL THING.--The history
of flying machines, short as it is, furnishes many
examples of one striking fact: That area has
but little to do with sustaining an aeroplane when
once in flight. The first Wright flyer weighed
741 pounds, had about 400 square feet of plane
surface, and was maintained in the air with a 12
horse power engine.

True, that machine was shot into the air by a
catapult. Motion having once been imparted to it,
the only thing necessary for the motor was to
maintain the speed.

There are many instances to show that when
once in flight, one horse power will sustain over
100 pounds, and each square foot of supporting
surface will maintain 90 pounds in flight.

THE LAW OF GRAVITY.--As the effort to fly
may be considered in the light of a struggle to
avoid the laws of nature with respect to matter,
it may be well to consider this great force as a
fitting prelude to the study of our subject.

Proper understanding, and use of terms is very
desirable, so that we must not confuse them.
Thus, weight and mass are not the same. Weight
varies with the latitude, and it is different at various