"The axle is getting overheated. See that can of oil yonder, Ferd? Come out of your trance and do something useful, boy! Quick! hand me the can." But it was Wyn who got it to him. Dave quickly refilled the oil cups and squirted some of the lubricant into the cracks about the shaft. The smoke immediately drifted away. "The rest of you go up where it's cooler," he commanded. "I will remain here and play engineer. And for goodness' sake, pray for the wind to die down!" The situation was really serious; nobody among the prisoners of the tower knew what to do. While the wind swung the arms of the mill round and round, there was no chance to get out. Not that they did not all cudgel their brains within the next hour to that end. There were enough suggestions made to lead to a dozen escapes; only--none of the suggestions were practical. It was less noisy, now that Dave had stopped the millstones; but the building continued to tremble, and the great wheel to creak. "What a donkey the man was to let them cut his door right behind the arms," exclaimed Frankie. "And with no proper means of stopping the sails from inside, once the wind began to blow," added Percy. "No. That's my fault," admitted Ferdinand. "I broke the gear some way." "Well, if we only had an axe," said one of the other boys, "we might cut our way out of the building on the side opposite the door." But Dave had already searched the mill for tools. There wasn't even a rope. Had there been, they could have let themselves down from the high window to the ground. "It should be against the law to build windmills without proper fire-escapes," declared Frank, trying to laugh. But it was hard to joke about the matter. It looked altogether too serious. The wind continued to blow steadily--a little harder, indeed, as time passed; but the sun grew hotter. It came noon, and they knew that those at Green Knoll Camp had long since expected them back. Finally a figure appeared upon the path far down the hill. They recognized Tubby Blaisdell trudging painfully up the slope in the hot sun, evidently an unwilling messenger from Mrs. Havel and Professor Skillings. They began to shout to Tubby, although they knew very well it was useless. He couldn't have heard their voices down there, even if the windmill hadn't made so much noise. But the girls fluttered their hats from the window and, bye and bye, the stolid fat youth, glancing up while he mopped his brow, caught sight of the signals. He halted, glared up at the window from under his hand, and then hurried his steps. "Oh, you Tubby!" shouted Frank, at last, thrusting her tousled curls out of the window. "Can't you help us?" He heard these words, and looked more bewildered than ever. "Say! what do you want?" he bellowed up at them. "Don't ask me to climb up those ladders, for I can't. And Mrs. Havel and the prof. say for you to come back to camp. They think a storm is coming. Besides--aren't you hungry?"