They had entered a forest of tall pines, so tall that the lads were obliged to crane their necks to see the tops.

“This is the beginning of the beginning,” announced Professor Zepplin somewhat enigmatically.  “This is the forest primeval.”

“I don’t know,” replied Chunky, peering through a car window.  “It strikes me that we’ve left the evil behind and got into the real thing.”

“What is it, Professor?” asked Tad Butler.

“As I have said, it is a primeval forest.  This great woodland stretches away from the very base of the San Francisco mountains southward for a distance of nearly two hundred miles.  We are taking a short cut through it and should reach Flagstaff in about an hour from now.”

“Hurrah!  We’re going to see the Flagstaff in an hour,” cried Stacy, his face wreathed in smiles.

“A further fact, which is no doubt unknown to you, is that this enormous forest covers an area of over ten thousand square miles, and contains six million, four hundred thousand acres.”

The boys uttered exclamations of amazement and wonder.

“If you’d said ten acres, I’d understand you better,” replied Stacy.  “I never could think in such big figures.  I’m like a rich fellow in our town, who doesn’t know what money is above a certain sum.”

“Well, what about it?” demanded Tad.

“Up to fifty dollars, he knows how much it is, but for anything above that it’s a check,” finished Chunky, looking about him expectantly.

No one laughed.

“Speaking of checks,” said Ned Rector after an interval of silence, “did you bring along that snaffle bit, Tad?”

“What snaffle bit?”

“The one we were going to put on Stacy Brown to hold him in check?”

A series of groans greeted Ned’s words.  Chunky grumbled something about making a checker board of Ned’s face if he didn’t watch out, after which the Professor turned the rising tide into other and safer channels by continuing his lecture on the great Arizona forest.

As the train dashed on the Pony Riders were greeted with occasional views of a mountain differing from anything they ever had seen.  One peak especially attracted their attention.  Its blackened sides, and its summit bathed in a warm glow of yellow sunshine, gave it a most striking appearance.

“What is it, Professor?” asked Tad, with an inquiring gaze and nod toward the mountain.

“Sunset Mountain,” answered Professor Zepplin.  “You should have discovered that.”

“But it isn’t sunset,” objected Walter.

“It is always sunset there.  The effect is always a sunset effect.”

“In the night, too!” questioned Chunky.

“No, it’s moonset then,” scoffed Rector.

“In the same direction you will observe the others of the San Francisco mountains.  However, we shall have more of this later on.  For the present you would do well to gather up Your belongings, for we shall be at our journey’s end in a few minutes.”