The pack mules had not yet come up with their driver.  The party foreseeing this, had brought such articles as would be needed for the night.  Taking their blankets and their rifles, together with food and wood for a fire, they began the slow, and what proved to be painful, ascent of Sunset Mountain.

A lava field stretched directly in front of them, barring the way.  Its forbidding surface had been riven by the elements until it was a perfect chaos of black tumult.  By the time the Pony Rider Boys had gotten over this rough stretch, they were ready to sit down and rest.  Nance would not permit them to do so.  He said they would have barely time to reach the crater before dark, as it was, and that they must make the best speed possible.  No one grumbled except Stacy, but it was observed that he plodded along with the others, a few paces to the rear.

The Professor now and then would point to holes in the lava to show where explosions had taken place, bulging the lava around the edge and hurling huge rocks to a considerable distance.  As they climbed the mountain proper they found that Sunset, too, had engaged in some gunnery in those far-away ages, as was shown by many lava bombs lying about the base.

The route up the mountain side was over a cider-buried lava flow, the fine cinders under foot soon making progress almost a torture.  Tad was the first to stand on his head as his feet went out from under him.  Stacy, in a fit of uproarious laughter, did the next stunt, that of literally standing on his right ear.  Chunky tried to shout and got his mouth full of cinders.

“I’m going back,” howled the fat boy.  “I didn’t come up here to climb slumbering volcanoes.”

“I’ll tell you what I’ll do, I’ll carry you, Stacy,” said Tad, smiling and nodding toward the cinder-blackened face of his companion.

“You mean it?”

“Of course I mean it.”

“I guess I can walk.  I’m not quite so big a baby as that.”

“I thought so.  Have your fun.  If you get into trouble you know your friend, Tad Butler, is always on the job.”

“You bet I do.  But this is an awful climb.”

It was all of that.  One step upward often meant a slide of several short steps backward.  The Professor’s face was red, and unuttered words were upon his lips.  Jim Nance was grinning broadly, his whiskers bobbing up and down as he stumbled up the side of Old Sunset.

“I reckon the tenderfeet will get enough of it before they get to the Canyon,” chuckled the guide.

“Say, Mr. Nance, we don’t want to Mister you all the time.  What shall we call you for short?” asked Tad Butler.

“Anything you want.”

“What d’ye say if we call you Whiskers?” called Stacy.

“Stacy!” rebuked the Professor sternly.

“Oh, let the little tenderfoot rant.  He’s harmless.  Call me Whiskers, if it does ye any good.”