It was about four o'clock one morning that Washington felt a slight jar to the submarine.
"Hope we ain't goin' to hit no more battleships," he said.
He glanced at the speed-indicating gage. To his surprise it stood at zero. The craft was not moving forward a foot! Yet the engines were going at half speed!
In great alarm Washington shut off the power and ran to acquaint Professor Henderson with the news.
"Suffin's ketched us!" cried the colored man.
"Nonsense!" said the inventor, yet he seemed alarmed as he slipped on his clothes and hastened to the conning tower.
He peered ahead along the path of water illuminated by the glare of the searchlight, but nothing was to be seen. Then he started the engine, increasing the speed gradually until the big screw in the shaft revolved more than one thousand times a minute. Still the Porpoise never stirred. She remained in the same position, as if some giant hand grasped her.
"Reverse the engine," said the professor.
Washington did so. To the surprise of both of them the ship shot backward like a frightened crab.
"Now forward!" exclaimed the old inventor.