inventor. To avoid accidents Koku
handled this himself, the hoisting apparatus being dispensed with. Tom
figured out that five hundred pounds of his new, powerful explosive
would be about the right amount to use, and this quantity, divided into
several packages to make the handling easier, was quickly inserted in
the breech of the gun by Koku.

"Bless my doormat!" cried Mr. Damon, who stood near, looking nervously
on. "Don't drop any of that."

"Me no drop," was the answer.

Tom was busily engaged in figuring on a bit of paper, and Ned, who
looked over his shoulder, saw a complicated compilation that looked to
be a combination of geometry, algebra, differential calculus and other
higher mathematics.

"What are you doing, Tom?" he asked.

"I'm trying to confirm my own theories by means of figures, to see if I
can really reach that farthest target."

"What, not the one thirty miles away.

"That's it, Ned. I want to get a thirty-mile range if I can."

"It isn't possible, Tom."

"Bless my tape measure! I should say not!" cried Mr. Damon.

"We'll see," replied Tom, quietly. "Put in the primer, Ned; and, Koku,
close the breech and slot it home."

In a few seconds the great gun was ready for firing.

"Now," said Tom, "this thing may be all right, and it may not. The
only thing that can cause an accident will be a flaw in the steel. No
one can guard against that. So, in order to be on the safe side, we
will all go into the bomb-proof, and I will fire the gun from there.
The wires are long enough."

They all agreed that this was good advice, and soon the steel men and
Tom's friends were gathered in a sort of cave that had been hollowed
out in the side of the hill, and at an angle from the big gun.

"If it does burst--which I hope it won't," said Tom, "the pieces will
fly in straight lines, so we will be safe enough here. Ned, are you are
ready at the instruments?"

"Yes, Tom."

"I want you to note the registered muzzle velocity. Mr. Damon, you will
please read the pressure gauge. After I press the button I'm going to
watch the landing of the projectile through the telescope."

The gun had been pointed, as I have said, at the farthest target--one
thirty miles away, telescope sights on the giant cannon making this
possible.

"All ready!" cried Tom.

"All ready," answered Ned.

There was a tense moment; Tom's thumb pressed home the electric button,
and then came the explosion.

It seemed for a moment a