Sandburr means to do?" asked Frank of the others.

"I don't think so," said Billy. "He is much older than we are and
doubtless he knows what he is about. At the same time, though, I think
we should watch and if he gets into trouble should try and help him
out of it."

"Very well, then we will all be out on deck at midnight," said Frank,
"and if we find that the professor is really serious in his intention
to go ashore in the boat we will try and stop him. If he still
persists we shall have to tell the captain."

The others agreed that the course that Frank recommended was the best
one, and they all decided to adopt his plan.

But the boys were heavy sleepers and besides were tired out when they
sought their bunks, so that when Frank, who was the first to wake,
opened his eyes it was past one in the morning. With a start the boy
jumped out of bed and hastily called the others.

"We may not be too late yet," he said, as he hastily slipped into
trousers, shirt and slippers.

But the boys WERE too late. When they reached the bow they could see
by peering over that the boat had gone and that the professor had
penetrated alone into the country of the Patagonians.

Suddenly there came a shot from the shore and a loud cry of:

"Help!"