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.

“We’d be sausage meat if we landed on those,” declared Chunky.

“You are likely to go through the machine if you don’t pay closer attention to your business,” answered Dad.

Carefully, cautiously, laboriously they lowered themselves one by one over the steep and slippery rocks, down, down for hundreds of feet until they stood on the ragged edge of nowhere, a direct drop of several hundred feet more before them.

The guide knew a trail further on, so they crept along the smooth wall of the Canyon with scarcely room to plant their feet.  A misstep meant death.

“Three hundred feet and we shall be there,” came the encouraging voice of the guide.  “Half an hour more.”

“I could make it half a minute if I wanted to,” said Stacy.  “But I don’t want to.  I feel it my duty to stay and look after my friends.”

“Yes, your friends need you,” answered Ned sarcastically.  “If they hadn’t I never should have pulled you out of the hole in the crater.”

“I was just wondering how Chunky could resist the temptation of falling in here.  He’ll never have a better opportunity for making a clean job of said Walter.

“He has explained why,” replied Tad.   “We need him.   Of course we do. 
We need him every hour-----”

“And a half,” added Ned.

The roar of the river became louder as they descended.  Now they were obliged to raise their voices to make themselves heard.  The Professor was toiling and sweating, but making no complaint of the hardships.  He was plucky, as game as any of those hardy boys for whom he was the companion, and they knew it.

“Hold on here!” cried Stacy, halting.

All turned to see what was wrong.

“I want to know—–­I want to know before I take another step.”

“Well, what do you want to know?” demanded Tad.

“If it’s all this trouble to climb down, I want to know how in the name of Bright Angel Trail we’re ever going to be able to climb up again!”

“Fall up, of course,” flung back the guide.  “You said this was mountain climbing backwards.  It’ll be that way going back,” chuckled the guide.

“And I so delicate!” muttered the lad, gazing up the hundreds of feet of almost sheer precipice.  But ere the Pony Rider Boys scaled those rocks again they would pass through some experiences that were far from pleasurable ones.

CHAPTER IX

CHUNKY WANTS TO GO HOME

Instead of a half hour, as had been prophesied, a full hour elapsed before they reached the bottom of the trail that was practically no trail at all.  Tad was sure that the guide couldn’t find his way back over the same ground, or rather rock, to save his life, for the boy could find nothing that looked as if the foot of man had ever trodden upon it before.  He doubted if any one had been over that particular trail from the Garden on.