The next day the Porpoise was taken below the surface, in order to allow of better speed being made. She was running along, submerged to a depth of two hundred feet, when there came a sudden jar, and the ship stopped.
"More trouble!" exclaimed the professor.
He opened the slide covering the bull's-eye windows and looked out. All about was swirling muddy water.
"Can you see anything?" the inventor called to Jack, who was in the conning tower.
"We've run into a mud-bank, and are stuck fast," called back the boy.
CHAPTER XIV
DIGGING OUT THE SHIP
"Reverse the engine!" called the professor. "Maybe we can back the ship out."
Washington set the big screw to revolving in the opposite direction. The Porpoise shook and shivered but the mud held her fast.