"It seems to me it is growing hotter," remarked Darry, after riding a quarter of a mile in silence.
"It is growing hotter," answered the old scout. "And that makes me more certain than ever that a storm's at hand."
"We'll have to take what comes," said Joe. "But I did hope we'd reach the fort by to-morrow."
On they went, around a bend of the trail and over some rough rocks, where the horses had to step with care, for fear of slipping into a gully on the left. Then they reached a patch of timber and plunged beneath the low-drooping trees. Here it was both dark and cool, and Darry breathed a long sigh of relief.
"How delicious!" he murmured. "It's almost like going into a cave. Benson, there must be lots of caves in these mountains," he went on reflectively.
"There are," answered the old scout. "I've been in a score or more."
"I should like to explore a big cave," came from Joe. "It would be a novelty to me."
"You may get the chance, lad," said Benson; "and get it soon."
"What do you mean? Are we going to ride by a cave?"
"There are a dozen or more ahead, and we may have to seek one of 'em for shelter. Do you hear that?"