subaltern. "It will be a wonderful machine
if, from that distance and height, it can glide into the Aerodrome."
And more than one express the opinion that it cannot be done; but
the Designer smiles to himself, yet with a little anxiety, for his
reputation is at stake, and Efficiency, the main reward he desires,
is perhaps, or perhaps not, at last within his grasp!

Swiftly the machine glides downwards towards them, and it can now be
seen how surprisingly little it is affected by the rough weather and
gusts; so much so that a little chorus of approval is heard.

"Jolly good gliding angle," says someone; and another, "Beautifully
quick controls, what?" and from yet another, "By Jove! The Pilot must be
sure of the machine. Look, he's stopped the engine entirely."

Then the Aeroplane with noiseless engine glides over the boundary of the
Aerodrome, and, with just a soft soughing sound from the air it cleaves,
lands gently not fifty yards from the onlookers.

"Glad to see you," says the Squadron Commander to the Pilot. "How do you
like the machine?" And the Pilot replies:

"I never want a better one, sir. It almost flies itself!"

And the Designer turns his face homewards and towards his beloved
drawing-office; well satisfied, but still dreaming dreams of the future
and ... looking far ahead who should he see but Efficiency at last
coming towards him! And to him she is all things. In her hair is the
morning sunshine; her eyes hold the blue of the sky, and on her cheeks
is the pearly tint of the clouds as seen from above. The passion of
speed, the lure of space, the sense of power, and the wonder of the
future ... all these things she holds for him.

"Ah!" he cries. "You'll never leave me now, when at last there is no one
between us?"

And Efficiency, smiling and blushing, but practical as ever, says:

"And you will never throw those Compromises in my face?"

"My dear, I love you for them! Haven't they been my life ever since I
began striving for you ten long years ago?"

And so they walk off very happily, arm-in-arm together; and if this
hasn't bored you and you'd like some more of the same sort of thing, I'd
just love to tell you some day of the wonderful things they accomplish
together, and of what they dream the future holds in store.

[Illustration]

_And that's the end of the Prologue._

CHAPTER I

FLIGHT

Air has weight (about 13 cubic feet = 1 lb.), inertia, and momentum.
It therefore obeys