"You are safe in making that remark now," retorted Fred. "I shan't forget it, however. You wait until we go back to Mackinac--" "I'm afraid if you wait until then," broke in George, "you'll forget all about his kind words. You don't suppose this fellow is really crazy, do you? He acts like a man beside himself." "That's as true as you live," said John in a whisper. "I'm wondering if we ought not to jump on him all together and take the wheel away from him." "They say a crazy man is ten times as strong as a man who isn't crazy," suggested Fred. "I don't believe we had better attempt that, yet awhile, anyway." "What's become of his man?" inquired Grant abruptly. "He isn't on the boat." "That's right," responded the boys all together, after they had glanced all about the boat, as if they were expecting to discover the guide whom Mr. Ferdinand Button had taken with him when the party had set out from Mackinac Island. "We're four to one anyway," said John. "I'm not in any hurry yet to try to do anything violent, but if the worst comes we ought to be able to handle him. There's a fellow for each foot and each hand and between us we ought to be able to take care of him." Meanwhile the swift little _Gadabout_ was speeding forward, as if it was governed by a spirit of its own. The water rushed past the stern, boiling and singing on its way. The eyes of the boys, more accustomed now to the dimness of the light, saw no objects in whichever direction they glanced over the dark waters. And the speed of the motor-boat was unchecked. Still the _Gadabout_ swept forward in its course. Not once did Mr. Ferdinand Button give any token to indicate that he was even aware of the presence of the boys on board the boat. He had not once glanced behind him and if he was looking steadily ahead, the boys, who frequently glanced in that direction, were unable to discover any object toward which he was guiding his course. Silence fell upon the little group seated in the stern of the motor-boat, and the depression which rested upon all alike seemed to deepen with the passing moments. Suddenly the speed of the _Gadabout_ slackened. A moment later the engine ceased to go and although the motor-boat was still moving swiftly forward it was doing so because of the headway under which it had been speeding. Instantly every boy leaped to his feet and stared blankly into the faces of his companions. In spite of the dimness of the light the alarm which every one felt was manifest and for a moment there was silence deep and intense. "What's that?" demanded Fred, who was the first to speak. "I give it up," replied John. "There's something happened." "You talk like a philosopher," said George impatiently. "As if we didn't know that! What's wrong, Mr. Button?" he added in louder tones. "I'm not sure," replied Mr. Button, who now turned and joined the boys. "I cannot quite make out whether our gasoline has given out or whether a blade in our propeller is broken."