s what you did, with that explosive shell, Mr. Swift. The
operator on the firing-zone ship saw the top fly off when the shell
struck. The ship was about half a mile away, and when they heard that
shell coming the officers thought it was all up with them. But,
instead, it passed over them and demolished the top of the mountain.

"Anybody hurt?" asked Tom, anxiously.

"No, it was an uninhabited island. But you have made the record shot,
all right. It went farther than any of the others."

"Then I suppose I ought to be satisfied," remarked Tom, with a smile.

"What was that disturbance, Mr. Swift?" asked the chief ordnance
officer, coming forward.

"I don't understand it myself," replied the young inventor. "It
appeared that someone went into the ammunition room, and Koku, my giant
servant, attacked him."

"As he had a right to do. But who was the intruder?"

"Herr von Brunderger's man."

"Ha! That German officer's! Where is he, he must explain this."

But Herr von Brunderger was not to be found, nor was his man in
evidence. They had fled, and when a search was made of their rooms,
damaging evidence was found. Before a board of investigating officers
Koku told his story, after the gun tests had been declared off for the
day, they having been most satisfactory.

The German officer's servant, it appeared, had managed to gain entrance
to the ammunition chamber by means of a false key to the outer door.
There were two entrances, the other being from the top of the platform
where the cannon rested. Koku had seen him about to throw something
into one of the ammunition cases, and had grappled with him. There was
a fight, and, in spite of the giant's strength, the man had slipped
away, leaving part of his garments in the grasp of Koku.

An investigation of some of the powder showed that it had been covered
with a chemical that would have made it explode prematurely when placed
in the gun. It would probably have wrecked the cannon by blowing out
the breech block, and might have done serious damage to life as well as
property.

"But what was the object?" asked Ned.

"To destroy Tom's gun," declared Mr. Damon.

"Why should von Brunderger want to do that?"

They found the answer among his papers. He had been a German officer of
high rank, but had been dismissed from the secret service of his
country for bad conduct. Then, it appeared, he thought of the plan of
doing some damage to a foreign country in order to get ba