“Good heavens!” he cried. “Fellows, did you hear that?”

The other had heard it, of course. How could they help hearing it? And they were simply dumfounded.

“Why, it’s a double echo!” cried one.

“And it sounded even louder than your voice!” added another. “What on earth do you suppose it can be?”

Rogers didn’t know, but he hazarded a guess.

“It must have been where I was standing,” he said. “This is the place. I’ll try it again.”

Then he took another deep breath, while the rest waited anxiously.

“Hello!” he roared.

There was not a sound. Mark kept as still as a mouse, though he and his friends were ready to burst with laughter. The yearlings gazed at each other in amazement.

“Jove, I missed it that time!” exclaimed Rogers. “I wonder what’s the matter?”