"Sare," spoke one of them with a bow, and his companion repeated the word. They both bowed to Ralph next, and stood like obedient children awaiting orders. Ralph was silent for fully a minute, studying their unfamiliar make-up. At that moment Fred Porter, having come down stairs the front way, strolled around the corner of the house. "This is my friend, Fred Porter--Zeph--Zeph Dallas, Porter," introduced the young railroader, and the two boys shook hands. Porter became instantly interested in the two strange lads. "I'm going to show you fellows something," said Zeph, "something mighty remarkable, something you never saw before, and it's going to beat anything you ever heard of. About those two boys. Kara!" One of the two lads instantly moved to the side of Zeph, who beckoned to him to follow him. He led the boy ten feet away behind a thick large bush, his back to the others. "Karo," he spoke again, and the other boy allowed him to turn him around where he stood, his back to the other boy. "See here, Zeph," spoke Ralph with a broad smile, "are you going to give us a detective demonstration of some kind, or a sleight-of-hand demonstration?" "Quit guying me, Ralph Fairbanks," said Zeph. "You're always at it, but I'm going to give you something this time that will make you sit up and take notice, I'll bet. Those boys came from a good many thousand miles away--from the other side of the world, in fact." "They look it," observed Fred Porter. "Gomera," exclaimed Zeph. "Where's that now?" inquired Fred. "It is the smallest of the Canary Islands." "Oh, that's it!" "And they talk without saying a word," was Zeph's next amazing announcement. "Whew!" commented Fred dubiously. "They do. It's that I'm going to show you. Perhaps those boys are the only two of their kind in the United States. They are Silvandos." "What are Silvandos, Zeph?" inquired Ralph. "Silvandos," replied Zeph, with manifest enjoyment of the fact that he was making a new and mystifying disclosure, "are persons who carry on a conversation through a whistling language." CHAPTER XVI ZEPH DALLAS AND HIS "MYSTERY" "Whistling language?" repeated Fred Porter. "Is there one?" "Aha! didn't I say I was going to show you something you never heard of before? You bet there is a whistling language!" chuckled Zeph--"and I'm now about to demonstrate it to you. You see these two boys? Well, they are natives of Gomera, the smallest of the Canary Islands. They were raised in a district where at times there is no living thing within sight, and the vast wilderness in the winding mountains is broken only by the crimson flower of the cactus growing in the clifts of the rock." "You talk like a literary showman, Zeph Dallas," declared Fred. "Well, I'm telling the story as I get it, ain't I?" demanded Zeph in an injured tone and with a sharp look at Fred, as if he suspected that he was being guyed. "Anyhow, I want to explain things so you'll understand."