A sudden sound had broken the stillness of the place. It was a sound that ordinarily would have caused confidence in the hearers. But heard under the circumstances in which it was, it was so unexpected, so out of keeping with the wild surroundings, that it startled and shocked them both.
It was the sound of laughter.
[CHAPTER XXV.]
THE MYSTERIOUS MEN.
There could be no mistake about it. It was human laughter that they had heard. It has been said that his ability to laugh is what chiefly distinguishes man from other animals and it is an undeniable fact that the sound resembles no other in nature.
The laughter they had heard was not loud, but it was none the less genuine and hearty on that account. Jack gripped Tom's arm and asked in an affrighted whisper:
"What does it mean, Tom?"
"It means that somebody is pleased over something," replied Tom, who, despite the light tone of his reply, was no less agitated than his companion, "but who can he be?"