At this there appeared to be some discontent among the survivors, and
they muttered to each other as they stood in a group on deck. But the
professor and his assistants were too busy with their preparations for
fixing the break to notice this.

While the men were gathered in a knot near the after part of the small
deck, the mate separated from them, and, coming close to where Mark
was standing, unscrewing some of the broken parts of the pipe said, in
a low voice.

"Tell the captain to watch out."

"What do you mean?" asked Mark quickly.

"Hush! Not so loud!" the mate exclaimed. "If the men hear me talking
to you, or see me, they may kill me. Tell the captain to look out;
that's all. Be on guard, and watch the engine room carefully."

"But why-- ?" Mark began, when, turning suddenly, the mate left him.
It was well he did so, for, at that instant, one of the sailors, who
had observed the two conversing, strolled in their direction.

Much alarmed, Mark sought Mr. Henderson and told him what he had
heard.

"I suppose the fire may have turned the poor man's head," the
scientist said. "I wonder if he thinks the men I rescued would mutiny
and take possession of my ship? If they did they would not know how to
work it, so what good would it do?"