As soon as they were out of earshot of the camp the mining man informed them of his suspicions and of what he had heard the night before.
"On thinking it over I am more than ever convinced that somebody must have been hovering about the camp last night," he declared, "but it is no use alarming the others unnecessarily, and, after all, I may be mistaken. In any event, from now on, we will post ourselves on sentry duty at night so as not to be taken by surprise in the event of any malefactors attacking us."
"Then you really think, sir, that somebody may have wind of the object of our journey and molest us?" inquired Roy soberly.
"I don't know; but it is always best to be on the safe side," was the rejoinder; "the towns on the edge of the desert are full of bad characters and it is possible that in some way the reason of our expedition has leaked out."
By this time they had walked as far as the mouth of one of the bare canyons that split the range of low, barren hills. Roy, whose eyes had been thoughtfully fixed on the ground, suddenly gave a sharp exclamation.
"Look here, Mr. Bell," he exclaimed, pointing downward, "what do you make of that?"
He indicated the imprints of a horse's hoofs on the dry ground.
"You have sharp eyes, my boy," was the reply; "those hoof-prints are not more than a few hot old, and certainly clinch my idea that someone on horseback was in the vicinity of the camp last night."
Jimsy looked rather grave at this. Roy, too, had a troubled note in his voice as he inquired:
"What do you make of it all, Mr. Bell?"