“That’s what he’ll do, for sure,” jeered Ned.  “But we’ll be on hand to take him down a peg or two.  Don’t you forget that, Chunky.”

Joking and enjoying themselves to the fullest, these brown-faced, hardy young travelers continued on, making camp that night by the roaring river, reaching Camp Butler the following forenoon.

Chow, the half breed pack-train man, met them with a long face.  The party saw at once that something was wrong.

“What’s happened?” snapped Nance.

“The dogs.”

“What about them?  Speak up.”

“Him dead,” announced the half breed stolidly.

“Dead?” cried Dad and the boys in one voice.

“Him dead.”

“What caused their death?”

The half breed shook his head.  All he knew was that 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.