"I think I'll take advantage of your kind offer, Fairbanks," responded Fogg. "I'm weak as a cat, and my head is going around like an electric turntable." Fogg started for home. Clark rode with Ralph on the locomotive to the roundhouse. The big engine was put into her stall. Then the boys left the place. "I have something to say to you, Fairbanks," began Clark. "I suppose so," replied Ralph. "It must be quite a long story, though." "It is," admitted his companion. "Then suppose we leave its recital till we are rested a bit," suggested Ralph. "I want you to come up to the house and have supper. Then we'll adjourn to the garden and have a quiet, comfortable chat." "That will be famous," declared Clark. "Say, you don't treat an imposter like myself courteous or anything, do you?" "Are you really an imposter?" asked Ralph, with a faint smile. "I am--and a rank one." "Just one question--you are not the real Marvin Clark?" "No more than yourself." "And you are Fred Porter?" "That's it." "I thought so," said the young engineer. CHAPTER XV "THE SILVANDOS" "I declare!" exclaimed Ralph Fairbanks. "For mercy's sake!" echoed Fred Porter. Both stood spellbound just within the grounds of the Fairbanks' home, where they had arrived. Over towards the dividing lot line of the next door neighbor, their eyes had lit upon an unusual and interesting scene. Two figures were in action among the branches of the great oak tree. They were boys, and their natural appearance was enough to attract attention. They were leaping, springing, chasing one another from branch to branch, with a remarkable agility that made one think of monkeys and next trained athletes. "Who are they, anyway?" demanded Fred. "They are new to me," confessed the young engineer. The two strangers were about of an age, under sixteen. It would puzzle one to figure out their nationality. Their faces were tawny, but delicate of profile, their forms exquisitely molded. They suggested Japanese boys. Then Ralph decided they more resembled lithe Malay children of whom he had seen photographs. At all events, they were natural tree climbers. They made the most daring leaps from frail branches. They sprung from twigs that broke in their deft grasp, but not until they had secured the purchase they aimed at in the act to send them flying through the air to some other perilous point in view. Their feats were fairly bewildering, and as one landed on the ground like a rubber ball and the other chased him out of sight in the next yard, Ralph conducted his companion into the house with these words: "That's odd enough to investigate." He did not announce his arrival to his mother, but led Fred up to his room. As he passed that now occupied by the Foggs, it made his heart glad to hear the fireman crowing at the baby to the accompaniment of a happy laugh from the fireman's wife.