When the lad uttered his signal, he was startled by the result.  A hundred echoes were awakened within the cavern, and the uproar fairly deafened him.  It seemed to him that ten thousand little imps were perched all around the cavern, with their fingers thrust in their mouths, waiting for him to start the tumult, when they joined in, with an effect that was overwhelming and overpowering.

“Good gracious!” he gasped, “I never heard anything like that.  I thought all the rocks were going to tumble down upon my head, and I believe some must have been loosened.”

He looked apprehensively at the dark, jagged points overhead.  But they were as grim and motionless as they had been during the many long years that had rolled over them.

“Mickey must have heard that, if he is anywhere within twenty miles,” he concluded.

But, if such was the case, he sent back no answering signal, as was his invariable custom, when that of his friend reached him.  Fred listened long and attentively, but caught no reply.

“I guess I’ll have to try it again,” he added, with a mingled laugh and shudder.  “I think these walls can stand a little more such serenading.”

He threw his whole soul in the effort, and the screeching whistle that he sent out was frightful, followed, as it was, by the innumerable echoes.  It seemed as if the walls took up the wave of sound as if it were a foot-ball and hurled it back and forth, from side to side, and up and down, in furious sport.  The dread of losing his torch alone prevented the lad from throwing it down and clapping his hands to his ears, to shut out the horrid din.  Some of the distant echoes, coming in after the others were exhausted, gave an odd, dropping character to the volleys of sound.

Had the expected reply of Mickey been the same as the call to him, the lad would have been deceived thereby, for the echoes, as will be understood, were precisely the same as answering whistles, uttered in the same manner.  But Fred understood that, if the Irishman heard him, he would reply with a series of short signals, such as are heard on some railroads when danger is detected.  But none such came, and he knew, therefore, that the ears which he intended to reach were not reached at all.

“I don’t understand that,” he mused, perplexedly, “unless he’s asleep yet.  When I left him, it didn’t seem as though he’d wake up in a week.  Perhaps he can hear me better if I shout.”

A similar racket was produced when the boy strained his lungs, but his straining ear could detect no other result.  It never once occurred to Fred that he and his friend were separated by such a distance that they could not communicate by sound or signal.  And yet such was the case, he having traveled much further than he suspected.

Having been forced to the disheartening conclusion that it was impossible to find the outlet by which the wolf had escaped, Fred had but one course left.  That was, to find his way back to the camp-fire in the shortest time and by the best means at his command.  If the mountain would not go to Mohammed, then Mohammed would have to go to the mountain.