“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 them to be on the way, because he desired to reach the rim of the crater while they still were able to see.  What his reasons were the boys did not know.  They took for granted that Dad knew his business, which Dad did.  He had spent many years in this rough country and knew it well.  The Grand Canyon was his home.  He lived in it the greater part of the year.  When winter came, Dad, with his mustang, his cattle and equipment would descend into the Grand Canyon far from snow and bitter cold into a land of perpetual summer, where, beside the roaring Colorado, he would spend the winter alone with his beloved Canyon.

Dad’s was a strange nature.  He understood the moods of the great gash in the plateau; he seemed literally to be able to translate the mysterious moans and whispers of the wind as it swirled between the rocky walls and went shrieking up the painted sides of the gulches.

But of all this the boys knew nothing as yet.  It was all to be revealed to them later.

“You’ll have a look over the country tomorrow,” said Dad.

“Where is the Canyon?” asked Tad, eager for a view of the wonderful spot.

“You’ll get a glimpse of it in the morning.  You’ll know the place when you get to it.  Here we be at the top.  There’s the hole.”

Chunky peered into the crater rather timidly.

“How do you get down?” he asked.

“Slide,” answered Ned.

“I can do that, but what’s at the bottom?”