"You must have eyes like a hawk," declared Stacy, with emphasis.

"Eyes were made to see with," answered Nance shortly.

"And ears to hear, and feet to foot with, and-----"

"Young men, it is time you were in bed. I presume Mr. Nance will be wanting to make an early start in the morning," said the Professor.

"If we are to get back the same day we'll have to start about daybreak.

It's a hard trail to pack. You'll be ready to stretch your legs when we get back to-morrow night."

The boys were not ready to use those same legs when they were turned out at daybreak. There was some grumbling, but not much as they got up and made ready their hurried breakfast. In the meantime Nance had gotten together such provisions as he thought they would need. These he had packed in the saddle bags so as to distribute the weight. Shortly after breakfast they made a start, Dad going first, Tad following close behind.

The first two miles of the Bright Angel Trail was a sort of Jacob's ladder, zigzagging at an unrelenting pitch. Most of the way the boys had to dig their knees into the sides of their mounts to prevent slipping over the animals' necks.

"This is mountain climbing backwards," jeered Stacy.

"I don't know, but I guess I like it the other way," decided Walter, looking down a dizzy slope.

"I hope my pony doesn't stumble," answered Ned.

"You won't know much about it if he does," called Tad over his shoulder.

"Never mind. We'll borrow an Indian basket to bring you home,"

laughed Stacy in a comforting voice.

The trail was the roughest and the most perilous they had ever essayed.

The ponies were obliged to pick their way over rocks, around sharp, narrow corners, where the slightest misstep would send horse and rider crashing to the rocks hundreds of feet below. But to the credit of the Pony Rider Boys it may be said that not one of them lost his head for an instant.

"How did this trail ever get such a name?" asked Tad of the guide.

"Yes, I don't see any signs of angels hereabouts," agreed Chunky.

"You never will unless you mend your ways," flung back Nance.

"Oh, I don't know. There are others."

"On the government maps this is called Cameron Trail, but it is best known by its original name, Bright Angel, named after Bright Angel creek which flows down the Canyon."

"Where is Bright Angel Canyon?" asked Tad.

"That's where the wild red men are hanging out," said Stacy.

"That's some distance from here. We shan't see it until some days later," replied the guide. "This, in days long ago, was a Havasupai Indian trail. You see those things that look like ditches?"

"Yes."

"Those were their irrigating ca.n.a.ls. They knew how to irrigate a long time before we understood its advantages. Their ca.n.a.ls conveyed large volumes of water from springs to the Indian Gardens beyond here. Yonder is what is known as the Battleship Iowa," said the guide, pointing to the left to a majestic pile of red sandstone that capped the red wall of the Canyon.

"Don't shoot," cried Stacy, ducking.

"You'll be shooting down into the Colorado," warned Nance. "You'd better watch out."

The rock indicated did very much resemble a battleship. The boys marveled at it. Then a little further on they came upon a sandstone plateau from which they could look down into the Indian Garden, another plateau rich with foliage, green gra.s.s and a riot of flowers.

It was like looking into a bit of the tropics.

"Here is the worst piece of trail we have yet found," called Nance.

"Go carefully," he directed when they reached the "blue lime." For the next few minutes, until they had pa.s.sed over this most dangerous portion, little was said. The riders were too busy watching out for their own safety, the Professor, examining the different strata of rocks that so appeal to the geologist. He was entranced with what he beheld about him. Professor Zepplin had no time in which to enjoy being nervous.

From there on to the Garden they rode more at ease in the "Boulder Bed,"

where lay large blocks of rock of many shapes and sizes that had rolled from some upper strata. Small shrubs and plants grew on every hand, many-hued lizards and inquisitive swifts darted across the trail, acting as if they resented the intrusion.

Chunky regarded the lizards with disapproving eyes. But his thoughts were interrupted by the voice of the guide pointing out the Temple of Isis that looks down six thousand feet into the dark depths of the inner abyss, surrounded by innumerable smaller b.u.t.tes. The wonderful colorings of the rocks did not suffer by closer inspection; in fact, the colors appeared to be even brighter than when viewed from the rim a few thousand feet above them.

Indian Garden was a delight. They wanted to tarry there, but were allowed to do so only long enough to permit horses and riders to refresh themselves with the cold water that trickled down through the ca.n.a.ls from the springs far above.

Reaching the end of Angel Plateau they gazed down a sheer descent of twelve hundred feet into the black depths of the inner gorge, where flowed the Colorado with a sullen roar that now was borne plainly to their ears.

"It sounds as I have heard the rapids at Niagara do," declared Chunky somewhat ambiguously.

"All off!" called the guide.

"What's off?" demanded Chunky.

"Dismount."

"Is this as far as we go?" questioned Tad.

"It is as far as we go on the pintos. We have to climb down the rest of the way, and it's a climb for your life."

The boys gazed down the wall to the river gorge. The prospect did not look very inviting.

"I guess maybe I'd better stay here and mind the 'tangs'," suggested Stacy, a remark that brought smiles to the faces of the other boys.

"No, you'd be falling off if we left you here," declared Dad. "You'll go along with us."

Before starting on the final thousand feet of the descent the trappings were removed from the horses, after which the animals were staked down so that they might not in a moment of forgetfulness fall over the wall and be dashed to pieces on the rocks below.

Dad got out his climbing ropes, the boys watching the preparations with keen interest.

"Are you going down, Professor?" asked Tad smilingly.

"Certainly I am going down. I for one have no intention of remaining to watch the stock," with a grim glance in Chunky's direction. Chunky saw fit to ignore the fling at him. He was gazing off across the chasm at the Temple of Isis, which at that moment absorbed his full attention.

"Now I guess we are ready," announced the guide finally. "I will go first. In places it will be necessary to cling to the rope. Don't let go. Then, in case you stumble, you won't get the nasty fall that you otherwise would be likely to get."

Away up, just below the Indian Garden, they picked up the slender trail that led on down to the roaring river. They had never had quite such a climb, either up or down.

Every time they looked down they saw a possible fall upon rough, blade-like granite edges.