ed on the
invitation of John Berwick to room with him as he was going to act as
assistant engineer on the voyage. This left Jim with a cabin to himself.

The boys had but just settled the matter when they were startled by a
series of loud and angry exclamations from the professor.

"Now, what do you think of that?" he cried, when the boys rushed into
the saloon where he was standing holding up his handbag in which a long
slit had been cut with a sharp knife.

"Their audacity passes all bounds!" he went on wrathfully. "They have
got it at last."

"What is lost?" asked Jim.

"The chart, the map of the island," replied the professor. "I don't know
as it will do any one else much good. Besides the points of the compass
it has only mystifying figures on it, but it's a bad loss for all that."

"Are you sure it is gone?" asked Jim.

"Well, it isn't here," replied the professor. "Fortunately, I can
remember the latitude and longitude, which is really the important
thing."

"What was the paper like?" put in Tom.

"It was just a rude chart," answered the professor. "It was in a flat
box. I put it in the box to keep it safe from getting wet or worn out. I
got tired of carrying it with me so I put it in the bag last night, not
intending the bag should get out of my sight. And I don't know when it
did."

"Looks as if we had spies all around us," said Jim.

"It certainly does," agreed the professor. "But now that we are on the
yacht we will be safe."

"Humph!" muttered Tom, who had just returned to the cabin after a
moment's absence, "I'm not so sure about that, but," he continued, "was
the box anything like this?" He held up to their gaze a thin oblong tin
box.

"Why, it looked like that!" exclaimed the professor, taking the box Tom
offered to him. "Why, it is it! What are you doing with it?"

"I found it in my bag this morning," explained Tom. "I thought that it
belonged to Jo, and that he had dropped it in by mistake."

"I suspect that is just what I did in an absent-minded spell this
morning," said the professor. "The joke is on me, boys. Perhaps it is a
lucky thing that I did it, for I think now, seeing this slit in my bag
that the best thing I can do is to have you take care of it for me."

"Don't you think you had better keep it?" protested Jim.

"Not after this experience," replied the professor, holding up the cut
bag. "Besides, I think it will be decidedly safer with you."

"Very well, then," replied