Jack moved back to the stern, where the box was, containing the red substance that furnished power to move the boat. He looked closely at it.
Meanwhile the boat was moving around in ever–narrowing circles, faster and faster. Jack noticed that twice in each revolution it went respectively lower and higher on the course, and always at the same places. That is to say, the whirlpool was on what might be termed a slant. At one time the boat would be at the lowest point, and at another at the highest point. At the low point the occupants of the craft were out of sight of everything, as when a ship is in the hollow of the sea. A little later they would be raised up on a crest of water so that they could look to the distant hills.
"If we could only get power enough to shoot the boat out at an angle when it gets to the high point, we could escape," thought Jack.
But how could he obtain this power? The mechanism seemed to be working at the greatest force, for, after an attempt had been made to stay the progress of the boat by reversing it, Mr. Roumann had again put on full speed ahead.
But was it full speed? That was what Jack wanted to know.
He examined every inch of the box. At first he saw nothing but the three knobs that had been used. Then, all at once, down underneath, he saw a small pin. It looked as if it could be moved. He took hold of it.
"I wonder what will happen if I pull it out or push it in?" he asked himself. Then he happened to remember that in an electric battery, to obtain more power, you must pull out a certain pin.
"Perhaps this works like an electric battery," he said. "I'll pull it out."
He did so, and a surprising thing happened. The boat shot forward at enormous speed, and as Jack happened to pull the pin out at a time when the craft was high up, it began to shoot across the water at an angle to the whirlpool. He had solved the problem of how to escape. As he afterward learned, the pin was just for the purpose for which he used it—to cause a sudden increase in speed.
The whirlpool did not give up without a struggle, but the boat was finally successful, and fought its way out to calm water.