at two mornings before
he had come in for breakfast, and upon going out again found the dogs
stretched out on the ground dead. That there was another mystery
facing them the boys saw clearly. Nance examined the carcasses of the
dead hounds. His face was dark with anger when he had finished.

"It's my opinion that those hounds were poisoned," he declared.

"Poisoned!" exclaimed the boys.

"Yes. There's some mysterious work being done around this camp. I'm
going to find out who is at the bottom of it; then you'll hear something
drop that will be louder than a boulder falling off the rim of the
Grand Canyon."

"This is a most remarkable state of affairs." said the Professor.
"Surely you do not suspect the man Chow?"

"No, I don't suspect him. It's someone else. I had a talk with Chief
Tom. He told me some things that set me thinking."

"What was it?" asked Tad.

"I'm not going to say anything about it just now, but I am going to have
this camp guarded after to-night. We'll see whether folks can come in
here and play tag with us in this fashion without answering to
Jim Nance."

"I'll bet the ghost has been here again," spoke up Stacy.

"Ghost nothing!" exploded Nance.

"That's what you said before, or words to that effect," answered the
fat boy. "You found I was right, though. Yes, sir, there are spirits
around these diggings. One of them carried away my gun."

"We will divide the night into watches after this. I am not going to
be caught napping again," announced Nance.

That night the guide sat up all night. Nothing occurred to arouse
his suspicion. Next day they went out lion hunting without dogs.
Nance got a shot at a cat, but missed him. The next day the Professor
killed a cub that was hiding in a juniper tree. It was his first kill
and put the Professor in high good humor. He explained all about it
that night as they sat around the camp fire. Then the boys made him
tell the story over again.

Nance took the first watch that night, remaining on duty until three
in the morning, when he called Tad. The latter was wide awake on the
instant, the mark of a good woodsman. Taking his rifle, he strolled
out near the mustangs, where he sat down on a rock. Tad was shivering
in the chill morning air, but after a time he overcame that. He grew
drowsy after a half hour of waiting with nothing doing.

All of a sudden the lad sat up wide awake. He knew that he had heard
something. That somet