"We'll let Flossie and Freddie start ahead of me," suggested Tommy, who, being a little elder than the two smaller twins, was a little better skater. "All right," agreed Bert. "Any way you like. Go ahead, Floss and Fred. Skate on until I tell you to wait. Then I'll give Tommy a starting place and, when we're all ready, I'll give the word to begin." Flossie and Freddie, hand in hand, skated ahead a little way. But Freddie's skate went over a little piece of wood on the ice and he tripped and fell, pulling Flossie down with him. The two plump twins were in a heap on the ice. "Hurt yourself?" asked Bert, as he started toward them, to help them up. "No--no--I--I guess not," answered Flossie, who was the first to get up. "We're all right," replied Freddie. "The ice was soft right there." "I guess it's because they're so fat, that they're soft, like a feather pillow," laughed Tommy. "They're getting fatter every day." "That's what they are," agreed Nan with a smile. "But they are pretty good skaters for such small children." "Everybody ready?" asked Bert, when the two small twins had taken their places, and Tommy Todd was between them and Bert and Nan. "All right," answered Freddie. "I am, too," came from Tommy. "Then go!" cried Bert, suddenly. The skating race was started. Merrily clicked the runners on the hard ice, leaving long white streaks where the children passed over. Flossie and Freddie were skating as fast and as hard as they could. "They are very anxious to win," said Nan, who was skating beside her brother. "Yes, but they can't keep going as fast as that all the way home." "You're going to let them win, aren't you?" asked Nan. "Sure I am! But they're so sharp we don't dare lag much behind. We must make a spurt toward the end, and pretend we did our best to beat them. Tommy Todd may come in ahead of them, though." "We can skate up to him and tell him not to," suggested Nan. "Good idea!" declared Bert. "We'll do it." The older twins skated a little faster to overtake Tommy, who was some distance behind Flossie and Freddie, when suddenly Nan gave a cry and clutched Bert by the arm. "Look!" she exclaimed, pointing with her hand. "An ice-boat," remarked Bert. "And going fast, too!" "Yes, but see! It's coming right toward Flossie and Freddie, and they're skating with their heads down, and don't see it! Oh, Bert! Yell at them! Tell them to look out! Yell at the man in the ice-boat!" It did indeed seem a time of danger, for a swift ice-boat--one with big white sails and runners, like large skates under it, was skimming over the frozen lake straight for the smaller twins. CHAPTER II BUILDING THE "BIRD"