.

But it was not until the last event of the day had been decided and the
crowd of spectators had broken up and gone their ways that the young
folk learned the mystery. Chet and Billy had been called to the
Detective Bureau, where the chief met them with rather a severe
countenance.

"So you two boys had no idea what was in that lard can you brought in
here the other day?" he demanded.

"No, sir," said Chet, manfully. "Billy heard those two men talking about
it. And he found it. He says he thinks there is money in it."

"And I should say there was!" ejaculated the police detective, with
disgust. "Those Italians had us all fooled. We got the big fellow, who
was sneaking back to try and get on the island again, and of course Tony
Allegretto and his monkey has always been right under our eyes.

"By the way, Master Long!"

"Yes, sir?" answered Billy, wondering what was coming.

"You said you thought those men surveying back of Stresch & Potter's the
day before the burglary, were working for the railroad?"

"That's what I thought, sir. I gathered it from what they said."

"And so they were. They were from the engineer's office of the C, P. &
L. We found 'em. They had nothing to do with the robbery."

"I didn't think they had. These two dagoes know about the robbery,
though!" exclaimed Short and Long, his eyes twinkling.

"I guess they do! I guess they do!" repeated the detective. "And the
money stolen from Stresch & Potter was in that soldered can. We got it.
We got the men. And the five hundred dollars will be divided between
this office and you boys."

"Not me!" cried Chet. "It belongs to Billy. He dived and found the can.
And--and I rather think he's paid for his reward by what he went through
over there on Cavern Island."

"Perhaps that's so," said the official, chuckling.

"But tell me, sir!" cried Billy, eagerly, "who got through that little
window and opened the door for the Italians?"

"Ha! that puzzled us a bit until one of our sharp young men watched Tony
putting that monkey of his through its tricks. Then we all saw a great
light."

"Great Scott! And so do I see a light!" cried Chet.

"Me, too," grumbled Billy. "But why didn't I guess it before and save
myself all that trouble I had?"

"The monkey is the guilty party," said the detective. "The bigger
Italian is a famous safe-cracker. He hired Tony Allegretto and his
monkey to help him get into the building, and to watch outside. Then the
tw