"Battle's over--cease firing!" laughed Allen. "Well, girls, what's the trouble?" he asked as he and his two friends advanced to meet Grace and Mollie, while Jake and Sam moved off in the direction of their cabin. "Oh, Will, there's a big express package for you at the cabin!" Grace exclaimed. "You owe me three dollars on it." "Good!" cried the lad. "I'll give you the money out of my next allowance. It's the motor boat, fellows," he added. "A motor boat!" cried Betty. "What good is a motor boat up here, with the river frozen?" "Oh, it's something new--a little idea of my own," said Will. "It's a converted motor-cycle gasoline engine, that can be attached to our ice boat. We're tired of having to depend on the wind. Now fellows, we'll have some fun. Hurry home, and we'll see if we can get it working to-day." "First you ought to do something to that eye," said Grace. "It will be black and blue; and you'll look disgraceful." "No one will see it up here," said Will calmly. "It doesn't matter." "Don't we girls matter?" demanded Mollie. "Oh, well, I'll put some raw beefsteak on it when I get to the cabin. I've heard that's good. Jake caught me a hard one in the eye." "Fighting! Disgraceful!" murmured Will's sister. "It was the best way out--snowballs," said Allen in a low voice, while Will and Frank were comparing notes. "It might have been more serious only for that. It was because they set the trap that Amy was caught in." "Oh, well then, I'm glad they did fight--with snowballs," returned Grace in a different tone. The big box had been unloaded in front of the cabin when the boys arrived, and while Grace and Mollie went in to talk to Betty and Amy, the boys proceeded to get out the motor. As Will had said this was one taken from a motorcycle. It was of two cylinders, and powerful. The boys planned to set it in the after part of the cockpit of the ice boat, and take off the sail. The motor would revolve a wheel at the stern, the wheel having spikes all around the rim. These spikes would dig into the ice and thus send the boat ahead. A lever was provided so that the spiked wheel could be pushed down lightly or hard on the ice, thus regulating the speed of the queer looking craft. The _Spider_ could be steered as before, by moving the rear runner. "Now we'll show you some sport!" cried Will, when he had seen that all the parts of the motor were there. "We'll go some, now!" But if the boys had hoped to try their new craft that day they were disappointed, for there was more work about installing the motor than they had calculated on. The girls grew tired of waiting, and strolled over to the village, the day being pleasant. They met Mr. Blackford coming from the depot, he having returned to complete his visit with the boys. He looked rather tired and discouraged, which prompted Betty to ask in a low voice: "Have you had any trace of your sister?"