it is," the
captain said. "At first we thought it was gold or jewels, for he goes
away off into the Andes Mountains, where both gold and jewels have been
found. He never looks for treasure, though, for though some of his
party have made rather rich discoveries, he takes no interest in them."

"What is he after then?" asked Mr. Titus.

"No one knows, and he won't tell. But whatever it is he has never found
it yet. Always, when he comes back, unsuccessful, from a trip to the
interior and goes back North with us, he will remark that he has not
the right directions. That he must seek again.

"Back he comes next season, as full of hope as before, but only to be
disappointed. Each time he goes to a new place in the mountains where
he digs and delves, so members of the parties he hires tell me, but
with no success. He carries with him something in a small iron box,
and, whatever this is, he consults it from time to time. It may be
directions for finding whatever he is after. But there seems to be
something wrong."

"This is quite a mystery," remarked Tom.

"It certainly is. But Professor Bumper is a fine man. I have known him
for years."

"This seems to dispose of the theory that he planted the bomb, and that
he is one of the plotters in the pay of Blakeson & Grinder," said Mr.
Titus, when he and Tom were alone.

"Yes, I guess it does. But who can have done it?"

That was a question neither could answer.

Tom had a theory, which he did not disclose to Mr. Titus, that, after
all, the somewhat mysterious Senor Pinto might, in some way, be mixed
up in the bomb attempt. But a close questioning of the steward on duty
near the foreigner's cabin at the time disclosed the fact that Pinto
had been ill in his berth all that day.

"Well, unless the bomb fell from some passing airship, I don't see how
it got on deck," said Tom with a shake of his head. "And I'm sure no
airship passed over us."

They had kept the matter secret, not telling even Mr. Damon, for they
feared the eccentric man would make a fuss and alarm the whole vessel.
So Mr. Damon, occasionally blessing his necktie or his shoe laces,
played chess with his elderly gentleman friend and was perfectly happy.

That Professor Bumper not only had kept his promise about not
mentioning the bomb, but that he had forgotten all about it, was
evident a day or two after the happening. Tom and Mr. Titus passed him
on deck, and bowed cordially. The professor returned the sal