"It is not a thief," he said to himself, "and it isn't any one who
has designs on one of the boats. He left that tent, but who is he
and what does he want?"

The silent figure, moving rapidly forward, presently left the line
of tents, and made for the cottage occupied by the doctor.

"I wonder if it is the doctor walking in his sleep?" thought Billy.
"That would be a great joke, wouldn't it?"

He thought he saw a flash of light for a moment, but was not sure
of this, and hurried on after the midnight prowler, having just time
to see him enter the window of the doctor's cottage.

"Can it be the doctor after all?" he muttered.

"That would be funny after all. I wish I had brought my light
with me. That's just like me, though, thinking of things when it
is too late." He stepped under the front window of the cottage,
through which he had seen the figure disappear and listened:

"I don't hear anything," he muttered. "I wonder if it could have
been the doctor? Burglars would have no good excuse for coming to
the camp. Who is it anyhow?"

Listening intently, he fancied he could hear some one moving about in
the cottage, and then the steps approached the window.

He was about to step back, but was a little too late in that, as he
had been in thinking of his pocket light.