satisfied, Professor Henderson?"

"Yes. I could not help but be after that demonstration, it is
wonderful."

"And you will make the projectile for me--for us?"

"I will. I'll start at once."

"Good! And I promise that you will come back from Mars even more
wealthy than you were when you returned from the center of the
earth."

"Most of that wealth is now gone," said Mr. Henderson with a
smile. "I have enough left, however, to build the projectile,
and we'll start at once."

"Hurrah for Mars!" cried Jack.

"And the marvelous red substance!" added Mark.

"Hush! Not a word about that!" cried Mr. Roumann warningly.
"That must be kept a profound secret!"

The next day the boys, Professor Henderson, Washington White, and
some trusty machinists began the building of the Annihilator, as
the projectile was to be called, because it was to annihilate
space.