ding 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."

"I'm no tenderfoot," protested Chunky.

"Nor be I all whiskers," returned the guide, whereat Chunky's face
turned red.

"I guess we'll call you Dad, for you'll have to be our dad for some time
to come," decided Tad.

"That'll be all right, providing it suits the fat little tenderfoot."

Stacy did not reply to this. He was having too much trouble to keep
right side up just then to give heed to anything else.

"Go zig-zag. You'll never get to the top this way," called Tad. "You
know how a switchback railroad works? Well, go as nearly like a
switch-back as possible."

"That's a good idea," agreed Dad. "You'll get there quicker, as the
young gentleman says."

Tad looked at his companions, grinning broadly. As they got nearer to
the top the color of the cinders changed from black to a brick red.
They began to understand why the peak of Sunset always presented such
a rosy appearance. It was due to the tint of the cinders that had been
thrown from the mouth of the volcano ages ago.

"We have now entered the region of perpetual sunset," announced the
Professor.

Chunky took advantage of the brief halt to sit down. He slid back
several feet on the treacherous footing.

Still further up the mountain took on a rich yellow color, but near the
rim it was almost white. It was a wonderful effect and caused the
Pony Riders to gaze in awe. But darkness was approaching rapidly. The
guide ordered t