At first, Frank thought nothing of this circumstance.

He bent over the brook, and plunged his hands into the water, when the thought occurred to him that this was a strange proceeding on the part of Arthur Vane.

If the latter had any thing to say to the chief, why did he not talk to him in the camp?
Frank's suspicions were aroused.

He stood, for a moment, undecided how to act, and then, dropping on his hands and knees, he crept cautiously around the end of the bowlder, and presently came in sight of Pierre and his companion.

They were sitting on the ground, facing each other--the chief calmly smoking a cigarette, while Arthur was amusing himself by cutting the grass around him with the Ranchero's bowie-knife.
"This is very odd," thought Frank.