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stated with perfect confidence； that shape or form
has nothing to do with the mere act of flying。 It
is simply a question of power。 This is a broad
assertion； and its meaning may be better understood
by examining the question of flight in a
broad sense。
A STONE AS A FLYING MACHINE。When a stone
is propelled through space； shape is of no importance。
If it has rough and jagged sides its speed
or its distance may be limited； as compared with
a perfectly rounded form。 It may be made in
such a shape as will offer less resistance to the air
in flight； but its actual propulsion through space
does not depend on how it is made； but on the
power which propelled it； and such a missile is a
true heavier…than…air machine。
A flying object of this kind may be so constructed
that it will go a greater distance； or require
less power； or maintain itself in space at
less speed； but it is a flying machine； nevertheless；
in the sense that it moves horizontally through the
air。
POWER THE GREAT ELEMENT。Now； let us examine
the question of this power which is able to
set gravity at naught。 The quality called energy
resides in material itself。 It is something within
matter； and does not come from without。 The
power derived from the explosion of a charge of
powder comes from within the substance； and so
with falling water； or the expansive force of
steam。
GRAVITY AS POWER。Indeed； the very act of the
ball gradually moving toward the earth； by the
force of gravity； is an illustration of a power
within the object itself。 Long after Galileo
firmly established the law of falling bodies it began
to dawn on scientists that weight is force。
After Newton established the law of gravitation
the old idea； that power was a property of each
body； passed away。
In its stead we now have the firmly established
view； that power is something which must have
at least two parts； or consist in pairs； or two elements
acting together。 Thus； a stone poised on
a cliff； while it exerts no power which can be
utilized； has； nevertheless； what is called potential
energy。 When it is pushed from its lodging place
kinetic energy is developed。 In both cases；
gravity； acting in conjunction with the mass of
the stone； produced power。
So in the case of gunpowder。 It is the unity of
two or more substances； that causes the expansion
called power。 The heat of the fuel converting
water into steam； is another illustration of the
unity of two or more elements； which are necessary
to produce energy。
MASS AN ELEMENT IN FLYING。The boy who
reads this will smile； as he tells us that the power
which propelled the ball through the air came
from the thrower and not from the ball itself。
Let us examine this claim； which came from a real
boy； and is another illustration how acute his mind
is on subjects of this character。
We have two balls the same diameter； one of
iron weighing a half pound； and the other of cotton
weighing a half ounce。 The weight of one
is； therefore； sixteen times greater than the other。
Suppose these two balls are thrown with the
expenditure of the same power。 What will be the
result！ The iron ball will go much farther； or；
if projected against a wall will strike a harder
blow than the cotton ball。
MOMENTUM A FACTOR。Each had transferred
to it a motion。 The initial speed was the same；
and the power set up equal in the two。 Why this
difference； The answer is； that it is in the
material itself。 It was the mass or density which accounted
for the difference。 It was mass multiplied
by speed which gave it the power； called； in
this case； momentum。
The iron ball weighing eight ounces； multiplied
by the assumed speed of 50 feet per second； equals
400 units of work。 The cotton ball； weighing 1/2
ounce； with the same initial speed； represents 25
units of work。 The term 〃unit of work〃 means
a measurement； or a factor which may be used to
measure force。
It will thus be seen that it was not the thrower
which gave the power； but the article itself。 A
feather ball thrown under the same conditions；
would produce a half unit of work； and the iron
ball； therefore； produced 800 times more energy。
RESISTANCE。Now； in the movement of any body
through space； it meets with an enemy at every
step； and that is air resistance。 This is much
more effective against the cotton than the iron
ball： or； it might be expressed in another way：
The momentum； or the power； residing in the
metal ball； is so much greater than that within the
cotton ball that it travels farther； or strikes a
more effective blow on impact with the wall。
HOW RESISTANCE AFFECTS THE SHAPE。It is because
of this counterforce； resistance； that shape
becomes important in a flying object。 The metal
ball may be flattened out into a thin disk； and now；
when the same force is applied； to project it forwardly；
it will go as much farther as the difference
in the air impact against the two forms。
MASS AND RESISTANCE。Owing to the fact that
resistance acts with such a retarding force on an
object of small mass； and it is difficult to set up a
rapid motion in an object of great density； lightness
in flying machine structures has been considered；
in the past； the principal thing necessary。
THE EARLY TENDENCY TO ELIMINATE MOMENTUM。
Builders of flying machines； for several
years； sought to eliminate the very thing
which gives energy to a horizontally…movable
body； namely； momentum。
Instead of momentum； something had to be
substituted。 This was found in so arranging the
machine that its weight； or a portion of it； would
be sustained in space by the very element which
seeks to retard its flight； namely； the atmosphere。
If there should be no material substance； like
air； then the only way in which a heavier…than…air
machine could ever fly； would be by propelling it
through space； like the ball was thrown； or by
some sort of impulse or reaction mechanism on
the air…ship itself。 It could get no support from
the atmosphere。
LIGHT MACHINES UNSTABLE。Gradually the
question of weight is solving itself。 Aviators are
beginning to realize that momentum is a wonderful
property； and a most important element in
flying。 The safest machines are those which have
weight。 The light； willowy machines are subject
to every caprice of the wind。 They are notoriously
unstable in flight； and are dangerous even
in the hands of experts。
THE APPLICATION OF POWER。The thing now to
consider is not form； or shape； or the distribution
of the supporting surfaces； but HOW to apply
the power so that it will rapidly transfer a machine
at rest to one in motion； and thereby get
the proper support on the atmosphere to hold it
in flight。
THE SUPPORTING SURFACES。This brings us to
the consideration of one of the first great problems
in flying machines； namely； the supporting
surfaces；not