times so fast!" declared the
giant, whose English was not much better than Eradicate's.

"Yes, I see," said Tom. "You are so strong, Koku, that you finished
your part before Eradicate did. Well, it was good of you to want to
help him."

At this the giant grinned at his rival.

"At the same time," went on Tom, winking an eye at Mr. Damon,
"Eradicate knows a little more about garden work, on account of having
done it so many years."

"Ha! Whut I tell yo', Giant!" boasted the colored man. It was his turn
to smile.

"And so," went on Tom, judicially, "I guess I'll let Rad finish spading
the garden, and you, Koku, can come and help me lift some heavy engine
parts. Mr. Damon wants to explain something to me."

"Ha! Nothing what so heavy Koku not lift!" boasted the giant.

"Go on! Lift yo'se'f 'way from heah!" muttered Eradicate as he picked
up his dropped spade. And then, with a smile of satisfaction, he fell
to work in the mellow soil while Tom led Koku to one of the shops where
he set him to lifting heavy motor parts about in order to get at a
certain machine that was stored away in the back of one of the rooms.

"That will keep him busy," said the young inventor. "And now, Mr.
Damon, I can listen to you. Do you really think you have a new idea in
airships?"

"I really think so, Tom. My Whizzer is bound to revolutionize travel in
the air. Let me tell you what I mean. Now cast your mind back. How many
ways are now used to propel an airship or a dirigible balloon through
the air? How many ways?"

"Two, as far as I know," said Tom. "At least there are only two that
have proved to be practical."

"Exactly," said Mr. Damon. "One with the propeller, or propellers, in
front, and that is the tractor type. The other has the propeller in the
rear, and that is the pusher type. Both good as far as they go, but I
have something better."

"What?" asked Tom with a smile.

"It's a Whizzer," said the eccentric man. "Bless my gold tooth! but
that is the best name I can think of for it. And, really, the propeller
I'm thinking of inventing does whiz around."

"But are you going to use a tractor or pusher type?" Tom wanted to know.

"It's a combination of both," answered Mr. Damon. "As it is now, Tom,
you have to get an aeroplane in pretty speedy motion before it will
rise from the ground, don't you?"

"Yes, of course. That's the principle on which an aeroplane rises and
keeps aloft, by its speed in the air. As soon as tha